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Materialchemie - Aktuelle Forschungsartikel renommierter Fachzeitschriften
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Aktuelle Fachartikel zur Chemie in den Materialwissenschaften, sortiert nach Erscheinungsdatum.
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beruecksichtige naturwissenschaftliche Journale: |
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Advanced Functional Materials - published by
Wiley-Interscience -
... publishes full papers, feature articles, and highlights on innovative and exciting research in all areas of materials science. |
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Advanced Materials - published by
Wiley-Interscience -
Read carefully selected, top-quality reviews, communications, and research news at the cutting edge of the chemistry and physics of functional materials as well as book reviews, product information, interviews, and a conference calendar. |
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Chemistry of Materials - published by
The American Chemical Society -
... covers solid-state chemistry, both inorganic and organic, and polymer chemistry, especially as directed to the development of materials with novel and/or useful optical, electrical, magnetic, catalytic, and mechanical properties. |
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Journal of Materials Chemistry - published by
The Royal Society of Chemistry -
High impact applications, properties and synthesis of exciting new materials |
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Journal of Materials Science - published by
Springer -
... publishes reviews, full-length papers, and short Communications recording original research results on, or techniques for studying the relationship between structure, properties, and uses of materials. |
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Nature Materials - published by
Nature Publishing Group -
... covers a range of topics within materials science, from materials engineering and structural materials. |
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Aktuelle wissenschaftliche Fachartikel der
genannten Journale: |
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Solution-Processable Septithiophene Monolayer Transistor
Septithiophene with endgroups designed to form liquid crystalline phases and allows controlled deposition of an electrically connected monolayer. Field effect mobilies mobilities of charge carriers and spectroscopic properties of the monolayer provide evidence of sustainable transport and delocalization of the excitation through intermolecular interactions within the layer.
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A Non-Fullerene Small Molecule as Efficient Electron Acceptor in Organic Bulk Heterojunction Solar Cells
A novel n-type small molecule FFI-1 was synthesized as the electron acceptor to replace PCBM in solution-processed organic BHJ solar cells. Its LUMO level (around -3.5 eV) both matches the work function of the cathode and increases VOC of the devices, making it a promising acceptor candidate. With P3HT: FFI-1 (1:2 w/w) as active layer and LiF/Al as the cathode, the best power conversion efficiency (PCE) reaches 1.86%.
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Cavitation Engineered 3D Sponge Networks and Their Application in Active Surface Construction
The design of the 3D architecture surfaces with both space- and time-dependent functionality (cell attraction, pH-trigged self-cleaning, antiseptic/disinfection) is in the focus. The innovative story includes: sonochemical surface activation, formation of feedback surface component (pH-responsible micelles), proof of responsive activity (time resolved cell adhesion and bacteria deactivation) and space adhesion selectivity (surface patterning).
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Robust Large Dimension Terahertz Cloaking
A large scale homogenous invisibility cloak functioning at terahertz frequencies is reported. The terahertz invisibility device features a large concealed volume, low loss, and broad bandwidth. In particular, it is capable of hiding objects with a dimension nearly an order of magnitude larger than that of its lithographic counterpart, but without involving complex and time-consuming cleanroom processing.
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Solid-State Lighting: Simple, Fast, Bright, and Stable Light Sources (Adv. Mater. 7/2012)
Light-emitting electrochemical cells (LECs) based on ionic transition-metal complexes operate with air-stable electrodes and are prepared using solution-based technologies. The presence of ions facilitates the formation of doped regions close to the electrodes, which reduces the barriers for electron and hole injection but also leads to exciton quenching. H. J. Bolink and co-workers demon-strate on page 897 the maintenance of optimum performance over several hundreds of hours by driving the LEC with a pulsed current, which stabilizes its dynamic configuration. This modus operandi leads to simple light sources with sub-second turn-on times and lifetimes in excess of 4000 hours. |
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Small Adsorbate-Assisted Shape Control of Pd and Pt Nanocrystals
AbstractThe shape control of noble metal nanocrystals is crucial to their optical properties and catalysis applications. In this Progress Report, the recent progress of shape-controlled synthesis of Pd and Pt nanostructures assisted by small adsorbates is summarized. The use of small strong adsorbates (e.g., I−, CO, amines) makes it possible to fabricate Pd and Pt nanostructures with not only well-defined surface structure but also morphologies that have not been achieved by other synthetic strategies. The roles of small adsorbates in shape control of Pd and Pt nanocrystals are discussed in the Report. Also presented in the Report are unique optical and catalytic properties of several Pd and Pt nanostructures (e.g., ultrathin Pd nanosheets, concave Pt octapod, concave Pd tetrahedra), as well as their bioapplications, to demonstrate the power of using small strong adsorbates in the shape control of Pt and Pd nanostructures.  The use of small strong adsorbates (e.g. I−, CO, amines) is demonstrated as a very effective strategy to control the shape of Pd and Pt nanocrystals with well-defined surface structures. Many nanocrystals obtained by this strategy have not been achieved by other synthetic strategies and exhibit novel optical, catalytic, and biological properties.
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Reversible Control of Electrochemical Properties Using Thermally-Responsive Polymer Electrolytes
A thermally responsive copolymer is designed to modulate the properties of an electrolyte solution. The copolymer is prepared using pNIPAM, which governs the thermal properties, and acrylic acid, which provides the electrolyte ions. As the polymer undergoes a thermally activated phase transition, the local environment around the acid groups is reversibly switched, decreasing ion concentration and conductivity. The responsive electrolyte is used to control the activity of redox electrodes with temperature.
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Simple, Fast, Bright, and Stable Light Sources
In this work we show that solution-processed light-emitting electrochemical cells (LECs) based on only an ionic iridium complex and a small amount of ionic liquid exhibit exceptionally good performances when applying a pulsed current: sub-second turn-on times and almost constant high luminances (>600 cd m−2) and power efficiencies over the first 600 h. This demonstrates the potential of LECs for applications in solid-state signage and lighting.
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Hydrogen Passivation Induced Dispersion of Multi-Walled Carbon Nanotubes
A method combining hydrogen passivation and ultrasonication was developed for the first time to disperse multi-walled carbon nanotubes (MWCNTs) in ethanol solution and epoxy resin. Excellent dispersion of MWCNTs was achieved in both media. Three-point bending tests of the MWCNT/epoxy nanocomposites revealed a remarkable increase in elastic modulus with increasing MWCNT content.
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From Monolayer to Multilayer N-Channel Polymeric Field-Effect Transistors with Precise Conformational Order
Monolayer field-effect transistors based on a high-mobility n-type polymer are demonstrated. The accurate control of the long-range order by Langmuir-Schäfer (LS) deposition yields dense polymer packing exhibiting good injection properties, relevant current on/off ratio and carrier mobility in a staggered configuration. Layer-by-layer LS film transistors of increasing thickness are fabricated and their performance compared to those of spin-coated films.
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Self-Assembled Flexible Microlasers
Hemispherical microresonators with tunable sizes are obtained based on the hydrophobic effect on distributed Bragg reflectors. Under optical excitation, whispering gallery mode lasing is observed from the dye-doped microresonators at room temperature. The results indicate the potential application of the flexible microresonators in photonic integrated circuits.
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Ultrafast Polymerization Inhibition by Stimulated Emission Depletion for Three-dimensional Nanolithography
To identify the depletion mechanismin a stimulated-emission-depletion (STED) inspired photoresist composed of a ketocoumarin photoinitiator in pentaerythritol tetraacrylate, we perform lithography with pulsed excitation and tunable delayed depletion. A fast component can unambiguously be assigned to stimulated emission. Our results allow the systematical optimization of the conditions in next-generation STED direct-laser-writing optical lithography.
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Photoresponsive Block Copolymer Photonic Gels with Widely Tunable Photosensitivity by Counter-Ions
Block copolymer photonic crystals comprising polyelectrolyte hydrogels exhibit strong reflective multicolors in response to near-UV radiation. Due to unique volume transition of swollen gels, the photonic gels show high photosensitivity, and which can be widely tunable by exchanging counter-anions. Multicolor photonic patterns created by photolithography can be repeatedly fixated and reactivated by sequentially exchanging counter-anions with different photosensitivity.
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Responsive Macroscopic Materials From Self-Assembled Cross-Linked SiO2-PNIPAAm Core/Shell Structures
AbstractA way to obtain macroscopic responsive materials from silicon-oxide polymer core/shell microstructures is presented. The microparticles are composed of a 60 nm SiO2-core with a random copolymer corona of the temperature responsive poly-N-isopropylacrylamide (PNIPAAm) and the UV-cross-linkable 2-(dimethyl maleinimido)-N-ethyl-acrylamide. The particles shrink upon heating and form a stable gel in both water and tetrahydrofuran (THF) at 3–5 wt% particle content. Cross-linking the aqueous gel results in shrinkage when the temperature is increased above the lower critical solution temperature and it regains its original size upon cooling. By freeze drying with subsequent UV irradiation, thin stable layers are prepared. Stable fibers are produced by extruding a THF gel into water and subsequent UV irradiation, harnessing the cononsolvency effect of PNIPAAm in water/THF mixtures. The temperature responsiveness translates to the macroscopic materials as both films and fibers show the same collapsing behavior as the microcore/shell particle. The collapse and re-swelling of the materials is related to the expelling and re-uptake of water, which is used to incorporate gold nanoparticles into the materials by a simple heating/cooling cycle. This allows for future applications, as various functional particles (antibacterial, fluorescence, catalysis, etc.) can easily be incorporated in these systems.  Responsive core/shell microparticles are used for the production of macroscopic materials such as films, fibers, and gels. Both aqueous and tetrahydrofuran gels are formed. By cross-linking of the particles, the temperature responsiveness of the particles is translated to the aqueous gels, films, and fibers, making them shrink and swell. This is used for post-incorporation of nanoparticles that can be taken up from the surrounding solution during swelling.
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Utilization of All Hydrothermally Synthesized Red, Green, Blue Nanophosphors for Fabrication of Highly Transparent Monochromatic and Full-Color Plasma Display Devices
AbstractVisible transparency is one of the attributes pursued in the advancement of display devices. Such a transparency can be realized in a plasma display device simply by applying Y(V,P)O4:Eu red-, Y(V,P)O4:Tm blue-, and LaPO4:Ce,Tb green-emitting nanophosphors with a controlled particle size and reasonable luminescence. The nanophosphors of three primary colors are all hydrothermally synthesized and annealed at appropriate conditions. Highly transparent, uniform emissive layers are deposited by screen-printing the nanophosphor pastes. Using respective screen-printed nanophosphor layers of red, blue, and green, monochromatic transparent test panels of plasma display are fabricated and characterized. Ultimately, a white-luminescing full-color transparent panel is successfully demonstrated by line-patterning the individual nanophosphor layers. Furthermore, for an effort to extract more photons and thus improve the brightness of the test panel, polystyrene monolayer-based 2D photonic crystal is introduced as a scattering medium on the outer surface of the panel and its usefulness was proved.  Using hydrothermally synthesized red Y(V0.5,P0.5)O4:Eu, blue Y(V0.5,P0.5)O4:Tm, and green LaPO4:Ce,Tb nanophosphors, highly transparent emissive layers are screen-printed. Monochromatic test panels of transparent plasma display are fabricated by the simple combination of the rear plate (nanophosphor/glass) with the front plate of the current ac-plasma display panels and a white luminescent full-color transparent panel is demonstrated.
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Reversible Switch Memory Effect in Hydrogen-Terminated Ultrananocrystalline Diamond
AbstractInnovative memory switch devices require reliable bistable conductance properties. It would be desirable if such bistable characteristics were available in robust solid state materials, such as diamond, which benefit from outstanding physical properties. A bistable current with reversible switching effect from surface transfer doped ultrananocrystalline diamond thin films measured by electron field emission is reported. This switching is manifested by the appearance of huge jumps in the current emission, up to four orders of magnitude, that occur at specific extracting electric field values. Persistent hysteresis is exhibited whenever the field is ramped down. It is proposed that these phenomena are the result of resonant-tunneling through a double barrier junction composed of tetrahedral amorphous carbon (ta-C)/nanodiamond/adsorbent/vacuum. This finding may pave the way for the realization of novel types of memory switch devices with unprecedented performance.  Reversible bistable current with a switching effect of the electron field emission from surface transfer doped ultrananocrystalline diamond thin films is reported. This switching is manifested by abrupt jumps in the current emission at specific extracting electric field values. Persistent hysteresis is exhibited whenever the field is ramped down. This finding may lead the way to novel memory switch devices with unprecedented performance.
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Controlled Colloidal Assembly: Experimental Modeling of General Crystallization and Biomimicking of Structural Color
AbstractThis paper aims to give an overview on the recent progress of controlled colloidal assembly as a unique experimental modeling system to study the general crystallization mechanism, i.e., the kinetics of nucleation, growth, and defects formation, and as a template for photonic crystals engineering. Such a system allows us not only to visualize some “atomic” details of the nucleation and surface process of crystallization, but also to treat quantitatively the previous models to an extent that has never been achieved before by other approaches. As such, the kinetic process of nucleation was quantitatively examined at the single particle level for the first time, allowing the identification of the deviations from the classical theories. The application of the electrically controlled colloidal crystallization to the modeling of the kinetics of some important processes of crystallization, i.e., multistep crystallization, supersaturation-driven structural mismatch nucleation, defect creation and migration kinetics, surface roughening, etc., has brought our knowledge to a new phase. Apart from the fundamental aspects, the controlled colloidal crystallization has attracted significant attention in many applications. In this regard, the application of colloidal crystallization to the fabrication of photonic crystals and the biomimicking of natural structure colors will be examined.  As a unique and new modeling approach, electrically controlled colloidal assembly enables the acquisition of comprehensive knowledge about nucleation, surface/kink kinetics, and crystal growth at the single growth unit level that has never been acquired before. In practical applications, colloidal crystallization can be adopted to produce structural colors on silk fabrics.
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Nanostructured Poly(styrene-b-butadiene-b-styrene) (SBS) Membranes for the Separation of Nitrogen from Natural Gas
AbstractThe preparation and characterization of new, tailor-made polymeric membranes using poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers for gas separation are reported. Structural differences in the copolymer membranes, obtained by manipulation of the self-assembly of the block copolymers in solution, are characterized using atomic force microscopy, transmission electron microscopy, and the transport properties of three gases (CO2, N2, and CH4). The CH4/N2 ideal selectivity of 7.2, the highest value ever reported for block copolymers, with CH4 permeability of 41 Barrer, is obtained with a membrane containing the higher amount of polybutadiene (79 wt%) and characterized by a hexagonal array of columnar polystyrene cylinders normal to the membrane surface. Membranes with such a high separation factor are able to ease the exploitation of natural gas with high N2 content. The CO2/N2 ideal selectivity of 50, coupled with a CO2 permeability of 289 Barrer, makes SBS a good candidate for the preparation of membranes for the post-combustion capture of carbon dioxide.  Tuning the morphology of poly(styrene-b- butadiene-b-styrene) (SBS) co-polymer membranes by means of the preparation procedure enhances the selective permeation of methane and CO2. New SBS membranes with outstanding gas separation properties are reported.
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Supercritical CO2: A Clean and Low Temperature Approach to Blending PDLLA and PEG
AbstractThe unique combination of the gas like viscosity and liquid like density of supercritical CO2 (scCO2) is exploited to blend poly(D,L-lactic acid) (PDLLA) and poly(ethylene glycol) (PEG) at near ambient temperatures. This novel process lowers the polymer blend viscosity and also permits incorporation of thermally and solvent labile protein based drugs. A series of blends are prepared with agitation in scCO2. Differential scanning calorimetry (DSC) data shows that miscible blends can be produced at moderate temperatures. A surprising region of miscibility is revealed between 8 and 25%w/w PEG. The properties of this miscible region are probed with high pressure parallel plate rheological studies, showing that the viscosity in scCO2 is directly related to the miscibility. Using the particles from gas saturated solutions (PGSS) method, microparticles of these PDLLA/PEG blends are produced using scCO2 and it is determined that the yields obtained are proportional to the miscibility of the polymers. Thus scCO2 provides a unique route to low temperature, solvent free processing that accesses a window of miscibility that has not previously been observed. Finally, DSC analyses of these sprayed microparticles confirm the presence of the same high miscibility region observed in the bulk samples prepared under supercritical conditions.  Supercritical CO2 (scCO2) is used to blend polymers poly(D,L-lactic acid) (PDLLA) and poly(ethylene glycol) (PEG) at surprisingly low temperatures. Differential scanning calorimetry (DSC) data highlight an unusual region of polymer miscibility between 8 and 25 wt% PEG. This miscibility region directly affects the viscosity of the blends in scCO2 and the particle yield from spraying. The particles produced also confirm the presence of this miscibility region.
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Local Organization of Graphene Network Inside Graphene/Polymer Composites
AbstractThe local electrical properties of a conductive graphene/polystyrene (PS) composite sample are studied by scanning probe microscopy (SPM) applying various methods for electrical properties investigation. We show that the conductive graphene network can be separated from electrically isolated graphene sheets (GS) by analyzing the same area with electrostatic force microscopy (EFM) and conductive atomic force microscopy (C-AFM). EFM is able to detect the graphene sheets below the sample surface with the maximal depth of graphene detection up to ≈100 nm for a tip-sample potential difference of 3 V. To evaluate depth sensing capability of EFM, the novel technique based on a combination of SPM and microtomy is utilized. Such a technique provides 3D data of the GS distribution in the polymer matrix with z-resolution on the order of ≈10 nm. Finally, we introduce a new method for data correction for more precise 3D reconstruction, which takes into account the height variations.  The conductive graphene network in a conductive graphene/polystyrene composite sample is separated from electrically isolated graphene sheets by analyzing the same area with conductive atomic force microscopy (C-AFM) and electrostatic force microscopy (EFM). The novel technique based on combination of scanning probe microscope and microtome is utilized for 3D reconstruction of the graphene sheets in the polymer matrix with z-resolution in the order of ≈ 10 nm.
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Cross-linkable nitrile functionalized graphene oxide/poly(arylene ether nitrile) nanocomposite films with high mechanical strength and thermal stability
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15780B, Paper Yingqing Zhan, Xulin Yang, Heng Guo, Jian Yang, Fanbin Meng, Xiaobo Liu
Cross-linkable nitrile functionalized graphene oxide/poly(arylene ether nitrile) nanocomposite films were synthesized via solution casting, showing significant enhancement in mechanical strength and thermal stability.
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Bottom-up synthesis of large-scale graphene oxide nanosheets
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15944A, Paper Libin Tang, Xueming Li, Rongbin Ji, Kar Seng Teng, Guoan Tai, Jing Ye, Changsong Wei, Shu Ping Lau
Glucose derived large-scale graphene oxide nanosheets with controllable thickness, electrical and optical properties.
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Production of novel microporous porphyrin materials with superior sensing capabilities
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15008E, Paper Michele Tonezzer, Gianluigi Maggioni, Enrico Dalcanale
New highly porous cobalt porphyrin films with superior sensing capabilities have been deposited by the novel Glow-Discharge-Induced-Sublimation (GDS) technique.
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High-performance organic thin-film transistors with polymer-blended small-molecular semiconductor films, fabricated using a pre-metered coating process
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16007B, Paper Byoungchoo Park, Hong Goo Jeon, Jinsung Choi, Y. K. Kim, Jongsun Lim, Junyoung Jung, Song Yun Cho, Changjin Lee
A novel method based on a simple pre-metered horizontal dipping process for organic thin-film transistors with TIPS-pentacene/poly([small alpha]-methylstyrene) films is reported for the first time. The method results in reliable, and reproducible, high-performance OTFT devices.
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ZnO/TiO2 core-brush nanostructure: processing, microstructure and enhanced photocatalytic activity
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15477C, Paper Xiaodong Yan, Chongwen Zou, Xiangdong Gao, Wei Gao
A heterostructure ZnO/TiO2 core-brush nanostructure has been synthesized on a glass substrate using a combination of aqueous solution growth and magnetron sputtering method. The core-brush structure showed an enhanced photocatalytic performance compared to TiO2 or TiO2/ZnO composite films.
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Multifold enhanced T2 relaxation of ZnFe2O4 nanoparticles by jamming them inside chitosan nanospheres
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15133B, Paper Ying Lin, Wei Yao, Yuan Cheng, Hanqing Qian, Xin Wang, Yin Ding, Wei Wu, Xiqun Jiang
ZnFe2O4 nanoparticles encapsulated in chitosan nanospheres have significantly enhanced transversal relaxivity due to the clustering and jamming effects.
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Non-covalently modified graphene sheets by imidazolium ionic liquids for multifunctional polymer nanocomposites
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16006D, Paper Ying-Kui Yang, Cheng-En He, Ren-Gui Peng, Avinash Baji, Xu-Sheng Du, Yuan-Li Huang, Xiao-Lin Xie, Yiu-Wing Mai
Simultaneous reduction and non-covalent functionalization of GO to produce a homogeneous graphene/polymer nanocomposite with excellent electrical, mechanical and thermal properties.
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Hyaluronic acid-conjugated mesoporous silica nanoparticles: excellent colloidal dispersity in physiological fluids and targeting efficacy
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15489G, Paper Ming Ma, Hangrong Chen, Yu Chen, Kun Zhang, Xia Wang, Xiangzhi Cui, Jianlin Shi
Hyaluronic acid-conjugated mesoporous silica nanoparticles (MSNs-HA) have been synthesized via a facile amidation reaction. This novel strategy can efficiently solve the agglomeration problem of MSNs in physiological fluids. Meanwhile, MSNs-HA showed the significant antitumor selectivity against CD44 over-expressing cells.
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Sol-gel processes at the droplet interface: hydrous zirconia and hafnia nanocapsules by interfacial inorganic polycondensation
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15353J, Paper Myriam Hajir, Paolo Dolcet, Viktor Fischer, Julian Holzinger, Katharina Landfester, Rafael Munoz-Espi
We present how the sol-gel precipitation of transition metal hydroxides, exemplified by the cases of zirconium and hafnium, can be driven to the interface of droplets in water-in-oil miniemulsions.
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ZnO nanostructures: growth, properties and applications
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15548F, Feature Article Aleksandra B. Djurisic, Xinyi Chen, Yu Hang Leung, Alan Man Ching Ng
Controversial and unresolved issues concerning ZnO nanostructures are discussed, with emphasis on areas needing further development.
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Switchable information carriers based on shape memory polymer
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16204K, Paper Thorsten Pretsch, Melanie Ecker, Markus Schildhauer, Michael Maskos
We describe a method for fabricating switchable QR code carriers. In a shape memory polymer surface, a QR code can be rendered non-decodable through functionalization and re-decodable by triggering the shape memory effect.
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First time investigation of Pt nanocatalysts deposited inside carbon mesopores of controlled length and diameter
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM00137C, Paper Dustin Banham, Fangxia Feng, Tobias Furstenhaupt, Siyu Ye, Viola Birss
We report the first synthesis and evaluation of a series of Pt/C oxygen reduction catalysts, having both controlled pore depth and diameter, for fuel cell and related electrochemical applications.
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Synthetic routes toward MOF nanomorphologies
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15675J, Feature Article Erik A. Flugel, Annekathrin Ranft, Frederik Haase, Bettina V. Lotsch
We highlight recent advances in the rational design of zero-, one- and two-dimensional metal-organic framework nanomorphologies that furnish insights into nucleation and growth at the nanoscale.
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Co3O4/Ni(OH)2 composite mesoporous nanosheet networks as a promising electrode for supercapacitor applications
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15863A, Paper Jin-Hui Zhong, An-Liang Wang, Gao-Ren Li, Jian-Wei Wang, Yan-Nan Ou, Ye-Xiang Tong
Co3O4/Ni(OH)2 composite mesoporous nanosheet networks (NNs) were synthesized from Co(OH)2/Ni(OH)2 NNs, and they showed high specific capacitance and long-term cyclability.
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Noise-Assisted Crystallization of Opal Films
AbstractAn improvement of the crystal quality of opal films self-assembled from polymer spheres in a moving meniscus using the agitation by white noise acoustic vibrations is demonstrated. A tenfold higher ordering of a hexagonal sphere packing in the (111) plane is achieved. This crystallization method, the mechanism of which is described in terms of the stochastic resonance, is a contrast to the widely used approach based on maintaining equilibrium conditions during the crystallization process. The precise quantification of the incremental lattice order improvement as a function of acoustic noise intensity is achieved by calculating the probability of finding an opposite partner for each sphere in the lattice. This method is examined against conventional and established techniques such as Fourier transforms and translational and bond-orientational correlation functions, and its advantages are demonstrated. Rotational symmetry analysis of diffraction resonances in measured and calculated optical transmission spectra as a function of the azimuth lattice orientation are carried out to confirm that the surface ordering translates into the bulk ordering of high index crystal planes, which are most sensitive to disorder.  A tenfold improvement of thein-plane lattice ordering in opal films is achieved using the non-equilibrium self-assembly of colloidal suspension under agitation by noise vibrations. A new and robust quantitative method of surface lattice ordering characterization is applied and results are compared with the optical diffraction at high-index crystal planes.
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Density Gradient Multilayer Polymerization for Creating Complex Tissue
An adaptable density gradient multilayer polymerization (DGMP) method facilitates simple fabrication of complex multicompartment scaffolds with structurally continuous interfaces. Solvent density liquid-liquid phase segregation compartmentalizes varied mechanical and chemical cues independently. Bulk photopolymerization produces stratified three-dimensional and two-dimensional matrices. Cells attach to patterned adhesion peptides on biomimetic 2D substrates.
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Linear Self-Assembly of Nanoparticles Within Liquid Crystal Defect Arrays
In the presence of oriented smectic liquidcrystal defects, hybrid systems of nanoparticles/liquid crystals form straight chains of nanoparticles of length longer than tens of micrometers and width equal to one single nanoparticle. The interparticle distance in a chain can be varied between a few micrometers and 1.5 nm, highlighting the control of optical absorption by light polarization monitored by gold nanoparticle concentration.
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Mesoporous Silica-Coated Gold Nanorods as a Light-Mediated Multifunctional Theranostic Platform for Cancer Treatment
Mesoporous silica-coated gold nanorods (Au@SiO2) are developed as a promising and versatile theranostic platform for cancer treatment. Intracellular localization of Au@SiO2 is visualized through two-photon imaging. With doxorubicin hydrochloride loaded, Au@SiO2–DOX show two light-mediated therapeutic modes: low power density laser-triggered drug release for chemotherapy, and high power density laser-induced hyperthermia, which suggest the potential for in-vivo applications.
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Sulfur-Tolerant Redox-Reversible Anode Material for Direct Hydrocarbon Solid Oxide Fuel Cells
A novel composite anode material consisting of K2NiF4-type structured Pr0.8Sr1.2(Co,Fe)0.8Nb0.2O4+δ (K-PSCFN) matrix with homogenously dispersed nano-sized Co-Fe alloy (CFA) has been obtained by annealing perovskite Pr0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ (P-PSCFN) in H2 at 900 °C. The K-PSCFN-CFA composite anode is redox-reversible and has demonstrated similar catalytic activity to Ni-based cermets anode, excellent sulfur tolerance, remarkable coking resistance and robust redox cyclability.
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Anisotropic Wetting Surfaces with One-Dimesional and Directional Structures: Fabrication Approaches, Wetting Properties and Potential Applications
AbstractThis review article provides a brief summary of recent research progress on anisotropic wetting on one-dimensional (1D) and directionally patterned surfaces, as well as the technical importance in various applications. Inspiration from natural structures exhibiting anisotropic wetting behavior is first discussed. Development of fabrication techniques for topographically and chemically 1D patterned surfaces and directional nanomaterials are then reviewed, with emphasis on anisotropic behavior with topographically (structurally) patterned surfaces. The basic investigation of anisotropic wetting behavior and theoretical simulations for anisotropic wetting are also further reviewed. Perspectives concerning future direction of anisotropic wetting research and its potential applications in microfluidic devices, lab-on-a-chip, sensor, microreactor and self-cleaning are presented.  New developments in anisotropic wetting on 1D and directional patterned surfaces in recent years (i.e., 2005–2011) are reviewed in this paper. Both natural surfaces and fabricated surfaces using various approaches with 1D patterned surfaces or directional nanostructures exhibit obvious anisotropic static or dynamic wetting behavior. Some modeling and simulation methods are proposed to interpret the observed anisotropic wetting. Many potential applications exist for anisotropic wetting surfaces.
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Asymmetric and symmetric PCR of gold nanoparticles: A pathway to scaled-up self-assembly with tunable chirality
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15800K, Paper Yuan Zhao, Liguang Xu, Hua Kuang, Libing Wang, Chuanlai Xu
In this work we used a polymerase chain reaction (PCR) to produce complex superstructures from heterogeneously-sized gold nanoparticles. By controlling the number of PCR cycles and primer density, two distinct superstructures were assembled at asymmetric and symmetric PCR.
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A binder-free process for making all-plastic substrate flexible dye-sensitized solar cells having a gel electrolyte
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15360B, Paper Li-Chieh Chen, Jyh-Ming Ting, Yuh-Lang Lee, Min-Hsiung Hon
Binder-free electrophoretic deposition (EPD) and mechanical compression were employed to fabricate TiO2 photoanodes for use in all-plastic substrate flexible dye-sensitized solar cells having a gel electrolyte.
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Functionalized polyacetylenes with strong luminescence: "turn-on" fluorescent detection of cyanide based on the dissolution of gold nanoparticles and its application in real samples
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15516H, Paper Xiaoding Lou, Qi Zeng, Yi Zhang, Zhaomin Wan, Jingui Qin, Zhen Li
By dissolution of Au NPs, new polyacetylene-functionalized Au-NPs were successfully developed as "turn-on" fluorescent probes for the detection of cyanide sensitively and selectively.
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Material considerations and locomotive capability in catalytic tubular microengines
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16813H, Highlight Gaoshan Huang, Joseph Wang, Yongfeng Mei
Tubular microengines harvesting chemical energy from catalytic reactions realize controllable autonomous locomotion at low Reynolds number.
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A novel conjugated polyfluorene: synthesis, characterization and application in label-free ECL immunoassays for biomarker detection
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15481A, Paper Mei Yan, Weiqiang Gao, Shenguang Ge, Lei Ge, Chengchao Chu, Jinghua Yu, Xianrang Song, Shengnan Hou
A novel amino-functionalized polyfluorene derivative was designed and synthesized. An ECL label-free immunosensor was prepared by chemical modification of a polyfluorene derivative on an ITO glass electrode.
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Improved thin film morphology and bulk-heterojunction solar cell performance through systematic tuning of the surface energy of conjugated polymers
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15517F, Paper Ying Sun, Shang-Chieh Chien, Hin-Lap Yip, Kung-Shih Chen, Yong Zhang, Joshua A. Davies, Fang-Chung Chen, Baoping Lin, Alex K.-Y. Jen
We have shown that significantly improved thin film morphology and bulk-heterojunction solar cell performance can be achieved by systematically tuning the surface energy of conjugated polymer donors through side-chain functionalization.
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One-Step Formulation of Protein Microparticles with Tailored Properties: Hard Templating at Soft Conditions
AbstractFormulation of therapeutic proteins into particulate forms is a main strategy for site-specific and prolonged protein delivery as well as for protection against degradation. Precise control over protein particle size, dispersity, purity, as well as mild preparation conditions and minimal processing steps are highly desirable. It is, however, hard to fit all these criteria with conventional preparation techniques. Here a one-step hard-templating synthesis of microparticles composed of functional, non-denatured protein is reported. The method is based on filling porous CaCO3 microtemplates with the protein near to its isoelectric point (pI) followed by pH- or EDTA-mediated dissolution of the tempplates. In principle, a wide variety of proteins can be converted into microparticles using this approach. The main requirement is an overlap of the protein insolubility and a template solubility for a certain parameter (here pH or EDTA). Here the formulation of insulin particles is studied in detail and it is shown that particles consisting of high molecular weight protein (catalase) can also be prepared. In this context, the synthesis of CaCO3 templates with controlled size, the mechanism of the protein microparticle formation and mechanical properties of the microparticles are discussed. For the first time, the fabrication of mesoporous monodispersed CaCO3 microtemplates with identical porocity but tuned diameter from 3 to 20 μm is demonstrated. The protein particle diameter can be adjusted by choosing the appropriate template size that is critical for successful pulmonary delivery of insulin. As a first step towards insulin delivery, the in vitro release of insulin at physiological conditions is studied.  Monodisperse microparticles with adjustable diameter composed from pure protein (insulin or catalase) are prepared under gentle conditions by hard-templating on porous decomposable CaCO3 microtemplates via isoelectric precipitation followed by pH- or EDTA-mediated template removal. The mechanism of the particle formation, mechanical properties, protein release, and potential for drug delivery applications are addressed.
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Wear-Resistant Nanoscale Silicon Carbide Tips for Scanning Probe Applications
AbstractThe search for hard materials to extend the working life of sharp tools is an age-old problem. In recent history, sharp tools must also often withstand high temperatures and harsh chemical environments. Nanotechnology extends this quest to tools such as scanning probe tips that must be sharp on the nanoscale, but still very physically robust. Unfortunately, this combination is inherently contradictory, as mechanically strong, chemically inert materials tend to be difficult to fabricate with nanoscale fidelity. Here a novel process is described, whereby the surfaces of pre-existing, nanoscale Si tips are exposed to carbon ions and then annealed, to form a strong silicon carbide (SiC) layer. The nanoscale sharpness is largely preserved and the tips exhibit a wear resistance that is orders of magnitude greater than that of conventional silicon tips and at least 100-fold higher than that of monolithic, SiO-doped diamond-like-carbon (DLC) tips. The wear is well-described by an atom-by-atom wear model, from which kinetic parameters are extracted that enable the prediction of the long-time scale reliability of the tips.  A novel process is described whereby the surfaces of nanoscale Si tips are exposed to carbon ions and then annealed to form a strong silicon carbide (SiC) layer. The nanoscale sharpness is largely preserved and the tips exhibit a wear resistance orders of magnitude greater than conventional silicon tips and at least 100-fold higher than monolithic, SiO-doped diamond-like carbon (DLC) tips.
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Stimuli-Free Reversible and Controllable Loading and Release of Proteins under Physiological Conditions by Exponentially Growing Nanoporous Multilayered Structure
AbstractA unique delivery system to reversibly and controllably load and release proteins under physiological conditions is desirable for protein therapeutics. We fabricate an ultrafast exponentially growing nanoporous multilayer structure comprised of two weak polyelectrolytes, poly(ethyleneimine) and alginate with thickness and chemical composition controlled by the assembly pH. For the first time, the assembled multilayered structure demonstrates stimuli-free reversible protein loading and release capability at physiological conditions by a synthetic material. The protein loading and release time can also be controlled by the assembled bilayer number. The highest loading capacity for the target protein and longest release time of proteins for layer-by-layer films reported to date have been achieved with a 15-bilayered film fabricated in this work. The prominent properties of the assembled film provide great potential for various biomedical applications, especially as a delivery system for protein therapeutics.  A novel nanoporous multilayeredPEI/alginate film is fabricated by exponentially growing, layer-by-layer self-assembly to serve as a carrier for protein loading and release. It is demonstrated to be the first artificial system reported to have the capability of stimuli-free reversible loading and release of proteins under physiological conditions and thus has great potential for various biomedical applications.
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Facilitation of Gene Transfection and Cell Adhesion by Gelatin-Functionalized PCL Film Surfaces
AbstractEfficient local gene transfection on a tissue scaffold is of crucial importance in facilitating tissue repair and regeneration. In this work, the gelatin-functionalized polycaprolactone (PCL) film surfaces are prepared via surface-initiated atom transfer radical polymerization of glycidyl methacrylate. The resultant covalent attachment of gelatin could enhance the cell-adhesion and local gene transfection properties. The gelatin-functionalized PCL film surfaces exhibit excellent cell-adhesion ability to both adherent and suspension cells. The attached adherent cells demonstrate the characteristic elongated morphologies with good spreading capability, while the attached suspension cells can maintain the original status of the round morphologies without spreading. More importantly, the gelatin coupled on the PCL surface could be used to absorb the cationic vector/plasmid deoxyribonucleic acid (pDNA) complexes via electrostatic interaction. The local gene transfection property on the immobilized cells is dependent on both the density of the immobilized cells and the loading types of pDNA complexes. The transfection efficiency of different assemble methods of pDNA complex was compared. With the pre- and post-loading sandwich-like gene transfection, the gelatin-functionalized PCL film surface can substantially enhance the transfection properties to different cell lines. The present study is very useful to spatially control local gene delivery within PCL-based tissue scaffolds.  Efficient local gene transfection on a tissue scaffold is of crucial importance in facilitating tissue repair and regeneration. The gelatin-functionalized polycaprolactone (PCL) film surfaces are prepared via surface-initiated atom transfer radical polymerization (ATRP) of glycidyl methacrylate (GMA), which could enhance the cell-adhesion and local gene transfection properties. With the pre- and post-loading sandwich-like gene transfection, the gelatin-functionalized PCL film surface can substantially enhance the transfection properties to different cell lines.
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Morphology and properties of TGDDM/DDS epoxy systems toughened by amino-bearing phenyl silicone resins
Abstract A series of amino-bearing phenyl silicone resins (APSR) were synthesized for toughening the tetraglycidyl 4,4′-diaminodiphenyl-methane
(TGDDM) epoxy resin cured with 4,4′-diamino diphenyl sulfone. The microstructure of the TGDDM/APSR resins was highly dependent
on the amino content of APSR and the loading level of the modifier. Based on the SEM and TEM studies, microstructure evolution
of the TGDDM/APSR resins in the curing process was imaged. The toughness of the TGDDM resin was effectively improved without
sacrificing the tensile strength, the flexural strength, and the modulus. The thermal stability and water resistance were
improved as well. However, the modifier brought in a noticeable lowering in the glass transition temperature.
- Content Type Journal Article
- Pages 1-13
- DOI 10.1007/s10853-012-6298-1
- Authors
- Ying Zhang, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 People’s Republic of China
- Chengyuan Shang, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 People’s Republic of China
- Xin Yang, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 People’s Republic of China
- Xiaojuan Zhao, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 People’s Republic of China
- Wei Huang, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 People’s Republic of China
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Shape-memory polymer networks from sol–gel cross-linked alkoxysilane-terminated poly(ε-caprolactone)
Abstract A novel type of covalently cross-linked semi-crystalline polymer with shape-memory and biocompatibility properties was prepared
from alkoxysilane-terminated poly(ε-caprolactone) (PCL) by sol–gel process that allowed the generation of silica-like cross-linking
points. A fine tuning of the cross-linking density and thermal properties (melting temperature) of the materials was obtained
by controlling the molecular weight of the PCL precursor (and thus the molecular structure of the resulting network) and the
curing conditions. The shape-memory behaviour was investigated with bending tests. Recovery times of less than one second
were observed in water depending on the temperature, and a linear correlation of the recovery time with cross-linking density
and molecular weight of PCL network precursor was observed.
- Content Type Journal Article
- Pages 1-9
- DOI 10.1007/s10853-012-6289-2
- Authors
- Katia Paderni, Department of Materials Engineering and Environment, University of Modena and Reggio Emilia, Via Vignolese 905/A, 41125 Modena, Italy
- Stefano Pandini, Consorzio Interuniversitario Nazionale per la Scienza e la Tecnologia dei Materiali (INSTM), Via Giusti 9, 50121 Firenze, Italy
- Simone Passera, Consorzio Interuniversitario Nazionale per la Scienza e la Tecnologia dei Materiali (INSTM), Via Giusti 9, 50121 Firenze, Italy
- Francesco Pilati, Department of Materials Engineering and Environment, University of Modena and Reggio Emilia, Via Vignolese 905/A, 41125 Modena, Italy
- Maurizio Toselli, Consorzio Interuniversitario Nazionale per la Scienza e la Tecnologia dei Materiali (INSTM), Via Giusti 9, 50121 Firenze, Italy
- Massimo Messori, Department of Materials Engineering and Environment, University of Modena and Reggio Emilia, Via Vignolese 905/A, 41125 Modena, Italy
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Preparation and thermophysical properties of nano-sized Ln2Zr2O7 (Ln = La, Nd, Sm, and Gd) ceramics with pyrochlore structure
Abstract Rare earth zirconates (Ln2Zr2O7, Ln = La, Nd, Sm, and Gd) with pyrochlore structure were prepared by hydrothermal method with polyethylene glycol as surfactant.
X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy,
Raman spectroscopy, and field emission scanning electron microscopy were utilized to characterize the phase structure, thermal
decomposition, and morphology of the products. Qualitative analysis indicates that the as-prepared zirconates are pyrochlore-type
structures. The specific surface area, lattice parameter, and average crystallite size of the as-prepared products are closely
related to the ionic radius. The activation energy of crystal growth shows an increasing trend with the decrease in ionic
radii. The sintering behavior of compacted body was also investigated, revealing that the sintering-resistance properties
of Ln2Zr2O7 are descending as the order of La2Zr2O7, Nd2Zr2O7, Sm2Zr2O7, and Gd2Zr2O7.
- Content Type Journal Article
- Pages 1-8
- DOI 10.1007/s10853-012-6293-6
- Authors
- Chunjie Wang, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Yue Wang, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Yongliang Cheng, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 China
- Wenzhi Huang, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Zuhair S. Khan, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Xizhi Fan, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Ying Wang, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Binglin Zou, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
- Xueqiang Cao, State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China
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Master curve of filler localization in rubber blends at an equilibrium state
Abstract In this study, the phase-specific localization of filler in NBR/NR blends was characterized by means of the selective extraction
method and wetting concept. A strong dependence of silica localization on the filler loading was found. A model based on thermodynamic
data was proposed for a quantitative prediction of filler localization in rubber blends. The filler localization can be described
by a master curve demonstrating a characteristic behavior in dependence on the filler surface tension data of blend components
and filler. The effect of filler loading on the silica localization is sufficiently explained by this model by taking into
consideration the deactivation of the silanol groups on the silica surface by adsorbed curing additives. Using the master
curve, the surface tension of filler affected by curing additives and silane addition can be estimated that may be useful
for evaluation and comparison of the effect of different coupling agents. Surface tension values of different fillers were
estimated by means of the master curve and they lie in the same order compared to those reported in literature. A potential
transfer of filler within a rubber blend can be also quantitatively predicted.
- Content Type Journal Article
- Pages 1-12
- DOI 10.1007/s10853-012-6277-6
- Authors
- H. H. Le, Center of Engineering Sciences, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
- K. Osswald, University of Applied Sciences, 06217 Merseburg, Germany
- S. Ilisch, Styron Deutschland GmbH, 06258 Schkopau, Germany
- X. T. Hoang, University of Technology, National University HCM, Ho Chi Minh City, Vietnam
- G. Heinrich, Leibniz Institute of Polymer Research (IPF) Dresden, 01069 Dresden, Germany
- H.-J. Radusch, Center of Engineering Sciences, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
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Human health hazards of persistent inorganic and carbon nanoparticles
Abstract Persistent inorganic and carbon nanoparticles are increasingly engineered for applications and may also be present in conventional
materials such as carbon black. Furthermore, they may originate from conventional non particulate materials by processes such
as wear and tear. Persistent inorganic and carbon nanoparticles can be hazardous to humans. Relatively much research regards
the hazards of inhaled nanoparticles. These may give rise to respiratory disease and to negative effects on other organs,
including the cardiovascular system. Determinants of risk of inhaled nanoparticles include: number, size, surface characteristics,
shape, structure, and the formation of assemblages. These determinants should preferentially be considered in exposure metrics.
A major molecular mechanism underlying the inhalation hazard of nanoparticles is the generation of reactive oxygen species,
but other mechanisms such as interactions with proteins and DNA may also contribute. Health hazards may also be linked to
ingestion of persistent inorganic and carbon nanoparticles, dermal exposure and exposure of the eye. Standards for workplace
exposure to persistent inorganic and carbon are currently emerging and there are options for hazard reduction by elimination
and substitution of hazardous nanoparticles and by engineering controls.
- Content Type Journal Article
- Category Review
- Pages 1-13
- DOI 10.1007/s10853-012-6288-3
- Authors
- L. Reijnders, IBED, University of Amsterdam, Science Park 904, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands
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Vapor Diffusion Sol-Gel Synthesis of Fluorescent Perovskite Oxide Nanocrystals
A model system consisting of Eu3+ as the activator ion and BaZrO3 as the host lattice is employed to demonstrate the potential of the vapor diffusion sol−gel method as a hydrolytic approach to the synthesis of fluorescent alkaline-earth perovskite oxide nanocrystals under ultrabenign conditions. The resulting nanocrystals are suitable precursors for nanostructured red-emitting phosphors.
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Structural and chemical characterization of SnO2-based nanoparticles as electrode material in Li-ion batteries
Abstract Improvement of long-term stability of electrode materials in Li-ion batteries requires a detailed understanding of influence
of synthesis parameters on surface chemistry and on properties. Therefore, bare SnO2 and core/shell nanoparticles with SnO2 core and a hydrocarbon shell are synthesized in an Ar/20% O2 microwave plasma, deposited as porous nanoparticle films in situ on heated Ni-substrates, and finally assembled as anodes
in Swagelok cells. In a comprehensive study, we investigate structure, particle size, chemistry, morphology, and water content
of the nanoparticles using X-ray diffraction, transmission electron microscopy, specific surface area analysis, and coulometric
water titration. The thicknesses of the nanoparticle films and their surface chemistry are investigated by scanning electron
microscopy and X-ray photoelectron spectroscopy. SnO2 nanoparticles are crystalline, with a tetragonal cassiterite structure. Primary particle sizes around 3 nm are reached for
the bare SnO2 particles, 5–8 nm for the cores of the core/shell nanoparticles. A minimum microwave power of 900 W is necessary to synthesize
SnO2 nanoparticles without precursor residuals as pristine SnO2 particles for the subsequent coating step. In the coating step increasing hydrocarbon content can be correlated with increasing
carbon-precursor feeding rate. Water uptake, stemming either from the process, or due to atmospheric contamination, can successfully
be reduced by a thermal treatment. The still remaining water is a function of specific surface area. Finally, bare SnO2 versus core/shell nanoparticles are compared regarding the influence of the shell on the electrochemical properties. The
principal improved functionality of the developed anodes in Swagelok cells is demonstrated.
- Content Type Journal Article
- Pages 1-9
- DOI 10.1007/s10853-012-6292-7
- Authors
- Dorothée Vinga Szabó, Institute of Applied Materials – Materials Process Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Goran Kilibarda, Institute of Applied Materials – Materials Process Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Sabine Schlabach, Institute of Applied Materials – Materials Process Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Vanessa Trouillet, Institute of Applied Materials – Materials Process Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Michael Bruns, Institute of Applied Materials – Materials Process Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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A Memristive Nanoparticle/Organic Hybrid Synapstor for Neuroinspired Computing
AbstractA large effort is devoted to the research of new computing paradigms associated with innovative nanotechnologies that should complement and/or propose alternative solutions to the classical Von Neumann/CMOS (complementary metal oxide semiconductor) association. Among various propositions, spiking neural network (SNN) seems a valid candidate. i) In terms of functions, SNN using relative spike timing for information coding are deemed to be the most effective at taking inspiration from the brain to allow fast and efficient processing of information for complex tasks in recognition or classification. ii) In terms of technology, SNN may be able to benefit the most from nanodevices because SNN architectures are intrinsically tolerant to defective devices and performance variability. Here, spike-timing-dependent plasticity (STDP), a basic and primordial learning function in the brain, is demonstrated with a new class of synapstor (synapse-transistor), called nanoparticle organic memory field-effect transistor (NOMFET). This learning function is obtained with a simple hybrid material made of the self-assembly of gold nanoparticles and organic semiconductor thin films. Beyond mimicking biological synapses, it is also demonstrated how the shape of the applied spikes can tailor the STDP learning function. Moreover, the experiments and modeling show that this synapstor is a memristive device. Finally, these synapstors are successfully coupled with a CMOS platform emulating the pre- and postsynaptic neurons, and a behavioral macromodel is developed on usual device simulator.  A synapstor (synapse-transistor), called NOMFET (nanoparticle organic memory field-effect transistor) is designed and fabricated to mimic the spike-timing dependent plasticity (STDP) of a biological synapse. STDP is a fundamental mechanism of learning in the brain. The STDP behavior means that the synaptic response (here the device conductance) depends on the time correlation between pre- and postsynaptic spikes received by the synapstor.
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Electrical Power From Nanotube and Graphene Electrochemical Thermal Energy Harvesters
AbstractNanocarbon-based thermocells involving aqueous potassium ferro/ferricyanide electrolyte are investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. The dependencies of power output on thermocell parameters, such as cell orientation, electrode size, electrode spacing, electrolyte concentration and temperature, are examined to provide practical design elements and principles. Observation of thermocell discharge behavior provides an understanding of the three primary internal resistances (i.e., activation, ohmic and mass transport overpotentials). The power output from nanocarbon thermocells is found to be mainly limited by the ohmic resistance of the electrolyte and restrictions on mass transport in the porous nanocarbon electrode due to pore tortuosity. Based on these fundamental studies, a comparison of power generation is conducted using various nanocarbon electrodes, including purified single-walled and multi-walled carbon nanotubes (P-SWNTs and P-MWNTs, respectively), unpurified SWNTs, reduced graphene oxide (RGO) and P-SWNT/RGO composite. The P-SWNT thermocell has the highest specific power generation per electrode weight (6.8 W/kg for a temperature difference of 20 °C), which is comparable to that for the P-MWNT electrode. The RGO thermocell electrode provides a substantially lower specific power generation (3.9 W/kg).  Nanocarbon-based thermocells involving aqueous potassium ferro/ferricyanide electrolyte are investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. The nanocarbon thermocell may become an attractive alternative for harvesting low-grade heat, given its simple design, direct thermal to electric energy conversion, continuous operation, low expected maintenance, and zero carbon emission.
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A Parallel Circuit Model for Multi-State Resistive-Switching Random Access Memory
AbstractLarge, rapidly growing literature is available on bipolar resistive-switching random access memories (RRAM) made of myriad of simple and advanced materials. Many of them exhibit similar resistance switching behavior but, until now, no unifying model can allow quantification of their voltage and time responses. Using a simple parallel circuit model, these responses of a newly discovered RRAM made of a thin-film random material are successfully analyzed. The analysis clearly reveals a large population of intermediate states with remarkably similar switching characteristics. Such modeling framework based on simple circuit constructs also appears applicable to several RRAM made of other materials. This simple approach to analyze data write/rewrite and memory retention in RRAM may aid their further understanding and development.  Multi-state resistance-switching thin film memory is modeled for the first time using a parallel circuit model, which successfully accounts for all the resistance-switching features as function of voltage and time, thus providing a unifying framework to predict fast data write/rewrite and memory retention.
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Interactions Between Amino Acid-Tagged Naphthalenediimide and Single Walled Carbon Nanotubes for the Design and Construction of New Bioimaging Probes
AbstractA new synthetic route to functionalized single walled carbon nanotubes (SWNTs) via supramolecular interactions using a specifically designed naphthalenediimide (NDI) nanoreceptor is demonstrated. The tendency of the NDI to spontaneously form composites with carbon nanomaterials leads to fluorescent amino acid tagged SWNTs, which are dispersible in widely accessible organic solvents (CHCl3, DMSO) as well as in biocompatible cell medium (EMEM, Eagle's modified essential medium). The X-ray crystal structure of the first iodine-tagged and amino acid-functionalized NDI molecule, designed especially to facilitate the high resolution transmission electron microscopy (HR TEM) imaging whilst retaining its ability to self-assemble into a nanodimensional receptor in weakly polar solvents, is also described. A new hybrid material, NDI@SWNT, was prepared and characterized as dispersed in organic solvents and aqueous media and in the solid state by HR TEM, tapping mode atomic force microscopy (TM AFM), scanning electron microscopy (SEM), circular dichroism, Raman and fluorescence spectroscopies (steady-state single and two-photon techniques). Combined microscopy techniques, density functional theory (DFT) calculations using the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) program and spectroscopic measurements in solution indicate that amino acid-functionalized NDI interacts strongly with SWNTs and forms a donor-acceptor complex. Density functional theory (DFT) calculations predicted the geometry and the binding energies of an NDI molecule loaded onto a SWNT strand and the possibility of charge transfer interactions within the hybrid. The NDI@SWNT composite translocates into cells (e.g. FEK-4, HeLa, MCF-7) as an intact object and localizes in the cells' cytoplasm and partially in the nucleus. The NDI coating enhances the biocompatibility of SWNTs and mediates its intracellular localization as shown by confocal fluorescence imaging and fluorescence lifetime imaging (FLIM) techniques. The excited state fluorescence lifetime of the probes in cells versus solution phase indicates that the probes remain unaffected by the change in their chemical environment within the experimental timescale (2 h).  The recognition and coating of single-walled carbon nanotubes (SWNTs) by an amino acid-derivatized naphthalenedi-imide, NDI, is demonstrated using circular dichroism, UV–vis, and fluorescence spectroscopies and probed in the solid state by high-resolution transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and atomic force microscopy. The translocation in cancerous and healthy cells of the resulting fluorescence NDI@SWNT nanohybrid can be imaged by laser scanning confocal microscopies and its integrity in vitro is probed by fluorescence lifetime imaging (FLIM) techniques.
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Efficient Organic Photovoltaic Cells Based on Nanocrystalline Mixtures of Boron Subphthalocyanine Chloride and C60
AbstractThe electrical and structural behavior of uniformly mixed films of boron subphthalocyanine chloride (SubPc) and C60 and their performance in organic photovoltaic cells is explored. Device performance shows a strong dependence on active-layer donor–acceptor composition, and peak efficiency is realized at 80 wt.% C60. The origin of this C60-rich optimum composition is elucidated in terms of morphological changes in the active layer upon diluting SubPc with C60. While neat SubPc is found to be amorphous, mixed films containing 80 wt.% C60 show clear nanocrystalline domains of SubPc. Supporting electrical characterization indicates that this change in morphology coincides with an increase in the hole mobility of the SubPc:C60 mixture, with peak mobility observed at a composition of 80 wt.% C60. Organic photovoltaic cells constructed using this optimum SubPc:C60 ratio realize a power conversion efficiency of (3.7 ± 0.1)% under 100 mW cm−2 simulated AM1.5G solar illumination.  Efficient organic photovoltaic cells based on nanocrystalline mixtures of boron subphthalocyanine chloride and C60 are characterized in terms of device performance, electrical transport, and film morphology. Device performance and hole mobility in uniform mixtures of boron subphthalocyanine chloride (SubPc) and C60 are optimized at a composition of 80 wt% C60. This C60-rich optimum results from the formation of nanocrystalline domains of SubPc at 80 wt% C60.
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Sensing of Vaporous Organic Compounds by TiO2 Porous Films Covered with Polythiophene Layers
AbstractThis paper describes the detection of volatile organic compounds (VOCs) through analyses of two output signals from integrated microcantilever sensor arrays coated with organic-inorganic hybrid sensing layers. The surface of TiO2 porous films was modified by amphiphilic terthiophene monomers and the adsorbed monomers were polymerized at the surface of TiO2 nanoparticles. The TiO2 porous films covered with polythiophene layers worked as highly sensitive sensing interfaces to provide two output signals for weight and resistance changes during exposure to VOC vapor. When the TiO2 porous films onto the sensor arrays were dyed with various kinds of amphiphilic monomers with different substituents, the resulting films provide exact information on VOC concentration from the mass changes as well as VOC classification from the analyses of response patterns.  The surface of TiO2 porous films is modified by terthiophene monomers and the adsorbed monomers are polymerized at the surface of TiO2 nanoparticles. The TiO2 porous films covered with polythiophene layers work as highly sensitive sensing interfaces to provide two output signals for weight and resistance changes during exposure to vapors of volatile organic compounds.
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Electric-Field-Assisted Charge Generation and Separation Process in Transition Metal Oxide-Based Interconnectors for Tandem Organic Light-Emitting Diodes
AbstractThe charge generation and separation process in transition metal oxide (TMO)-based interconnectors for tandem organic light-emitting diodes (OLEDs) is explored using data on electrical and spectral emission properties, interface energetics, and capacitance characteristics. The TMO-based interconnector is composed of MoO3 and cesium azide (CsN3)-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) layers, where CsN3 is employed to replace the reactive metals as an n-dopant due to its air stability and low deposition temperature. Experimental evidences identify that spontaneous electron transfer occurs in a vacuum-deposited MoO3 layer from various defect states to the conduction band via thermal diffusion. The external electric-field induces the charge separation through tunneling of generated electrons and holes from MoO3 into the neighboring CsN3-doped BPhen and hole-transporting layers, respectively. Moreover, the impacts of constituent materials on the functional effectiveness of TMO-based interconnectors and their influences on carrier recombination processes for light emission have also been addressed.  The impacts of constituent materials on the functional effectiveness of transition metal oxide-based interconnectors in tandem organic light-emitting diodes are addressed. Spontaneous electron transfer occurs in a vacuum-deposited MoO3 layer from various defect states to the conduction band via thermal diffusion. The external electric field induces charge separation through tunneling of generated electrons and holes from MoO3 into the neighboring electron- and hole-transporting layers.
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Self-Assembling Peptides as Cell-Interactive Scaffolds
AbstractCell and tissue engineering therapies for regenerative medicine as well as cell-based assays require an understanding of the interactions between cells with the surrounding microenvironment at the nanoscale. Engineering a cell-interactive scaffold therefore entails control over the nanostructure of the biomaterial. Peptides that are able to self-assemble into 3D scaffolds have emerged as interesting biomaterials for directing cell behavior, with desirable properties such as the capability of tuning the nanostructure by modulating the amino acid composition. Here, an overview of the development of self-assembling peptide hydrogels as functional cell scaffolds is presented, highlighting recent work on incorporating features such as bioactive ligands, growth factor delivery, controlled degradation, and formulation into microgels for defined cell microenvironments.  Self-assembling peptide hydrogels have great potential as cell scaffolds for a wide range of biological applications due to the ease of tuning their nanostructure and their innate biocompatibility. The recent progress made in functionalizing and improving the bioactivity of these materials to direct cell behavior is reviewed.
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Electroaddressing Functionalized Polysaccharides as Model Biofilms for Interrogating Cell Signaling
AbstractBacteria often reside at surfaces as complex biofilms in which an exopolysaccharide matrix entraps the population while allowing access to its chemical environment. There is a growing awareness that the biofilm structure and activity are integral to a wide array of properties important to health (the microbiome), disease (drug resistance) and technology (fouling). Despite the importance of bacterial biofilms, few experimental platforms and systems are available to assemble complex populations and monitor their activities. Here, a functionalized alginate composite material for creating in vitro model biofilms suitable for cell-cell signaling studies by entrapping bacterial cells in situ is reported. Biofilm assembly is achieved using device-imposed electrical signals to electrodeposit the stimuli-responsive polysaccharide alginate. This electrodeposition mechanism is versatile in that it allows control of the bacterial population density and distribution. For instance, it is demonstrated that a mixed population can be homogeneously distributed throughout the biofilm or can be assembled as spatially segregated populations within a stratified biofilm. The “electroaddressable” biofilms are visualized using both a planar 2D chip with patterned electrodes and a microfluidic bioMEMS device with sidewall electrodes. Specifically, it is observed that bacteria entrapped within the model biofilm recognize and respond to chemical stimuli imposed from the fluidic environment. Finally, reporter cells are used to demonstrate that bacteria entrapped within this model biofilm engage in intercellular quorum sensing. This work demonstrates the functionality of the stimuli-responsive polysaccharide by biofabricating pseudo-3D cell-gel biocomposites, mimicking the formation of biofilms, for interrogating phenotypes of E. coli bacterial populations. In addition to controlling assembly, the microfluidic device allows the biofilm to be monitored through the fluorescence methods commonly used in biological research. This platform technology should be able to be exploited for monitoring biofilm development, as well as for extending the understanding of the interactions between various bacterial species arranged in controlled patterns.  The functionality of stimuli-responsive polysaccharide alginate is demonstrated by biofabricating 3D cell-gel biocomposites, mimicking the formation of biofilms, for interrogating phenotypes of E. coli bacterial populations. By using device-imposed electrical signals, the bacterial population density and distribution can be spatiotemporally controlled. This approach can be exploited for investigating biofilm development and bacterial intra- and interspecies signaling in controlled patterns.
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Enhancing Light Emission of Nanostructured Vertical Light-Emitting Diodes by Minimizing Total Internal Reflection
AbstractNanostructured vertical light-emitting diodes (V-LEDs) with a very dense forest of vertically aligned ZnO nanowires on the surface of N-face n-type GaN are reported with a dramatic improvement in light extraction efficiency (∼3.0×). The structural transformation (i.e., dissociation of the surface nitrogen atoms) at the nanolevel by the UV radiation and Ozone treatments contributes significantly to the initial nucleation for the nanowires growth due to the interdiffusion of Zn into GaN, evident by the scanning photoemission microscopy (SPEM), high-resolution transmission electron microscopy (HR-TEM), and ultraviolet photoelectron spectroscopy (UPS) measurements. This enables the growth of densely aligned ZnO nanowires on N-face n-type GaN. This approach shows an extreme enhancement in light extraction efficiency (>2.8×) compared to flat V-LEDs, in good agreement with the simulation expectations (∼3.01×) obtained from 3D finite-difference time-domain (FDTD) tools, explained by the wave-guiding effect. The further increase (∼30%) in light extraction efficiency is also observed by optimized design of nanogeometry (i.e., MgO layer on ZnO nanorods).  Nanostructured vertical light-emitting diodes with a dramatic improvement in light extraction efficiency are reported, assisted by successful growth of densely aligned ZnO nanorods on GaN regardless of the surface polarity. The structural transformation on the surface, at the nanolevel by the UV/ozone treatments, contributes significantly to the initial nucleation due to interdiffusion of Zn into GaN. This enables the densely aligned ZnO nanorods to be grown on the N-face of n-GaN.
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Boron Subphthalocyanine Chloride as an Electron Acceptor for High-Voltage Fullerene-Free Organic Photovoltaics
AbstractHigh-efficiency fullerene-free single-heterojunction (SHJ) organic photovoltaic (OPV) cells consisting of tetracene (Tc) as a typical donor material and boron subphthalocyanine chloride (SubPc) as an acceptor material are reported. Cells containing SubPc as a direct replacement for C60 exhibit an ∼60% improvement in open circuit voltage (Voc) achieving a maximum Voc of 1.24 V, which is amongst the highest values acheived to date for SHJ devices. This resulted in an overall improvement of ∼60% in power conversion efficiency from 1.8%, for Tc/C60 cells, to 2.9% for Tc/SubPc. The OPV device results are complemented by soft X–ray photoelectron spectroscopy (PES) measurements of the interfacial energetics of both systems. The results demonstrate that SubPc shows considerable promise as an electron acceptor material for future cell designs.  High-efficiency fullerene-free single heterojunction organicphotovoltaic (OPV) devices are achieved via the replacement of C60 with the typical “donor” material boron subphthalocyanine chloride (SubPc). Devices containing SubPc achieve a 60% increase in open-circuit voltage, one of the largest to date for single heterojunction devices, allowing for an increase in cell efficiency from 1.8% to 2.9%.
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Evolution-Based Design of an Injectable Hydrogel
AbstractA new class of simple, linear, amphiphilic peptides are developed that have the ability to undergo triggered self-assembly into self-supporting hydrogels. Under non-gelling aqueous conditions, these peptides exist in a random coil conformation and peptide solutions have the viscosity of water. On the addition of a buffered saline solution, the peptides assemble into a β-sheet rich network of fibrils, ultimately leading to hydrogelation. A family of nine peptides is prepared to study the influence of peptide length and amino acid composition on the rate of self-assembly and hydrogel material properties. The amino acid composition is modulated by varying residue hydrophobicity and hydrophilicity on the two opposing faces of the amphiphile. The conformation of peptides in their soluble and gel state is studied by circular dichroism (CD), while the resultant material properties of their gels is investigated using oscillatory sheer rheology. One weight percent gels formed under physiological conditions have storage modulus (G′) values that vary from ≈20 to ≈800 Pa, with sequence length and hydrophobic character playing a dominant roll in defining hydrogel rigidity. Based on the structural and functional data provided by the nine-peptide family members, an optimal sequence, namely LK13, is evolved. LK13 (LKLKLKLKLKLKL-NH2) undergoes triggered self-assembly, affording the most rigid gel of those studied (G′=797 ± 105). It displays shear thin-recovery behavior, allowing its delivery by syringe and is cytocompatibile as assessed with murine C3H10t1/2 mesenchymal stem cells.  An evolution-based design strategy results in a peptide-based hydrogel capable of shear-thin delivery from a simple syringe. Gels with an optimal sequence, namely LK13, should find utility in the direct encapsulation and delivery of cells for tissue regenerative therapy.
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Encapsulating Elastically Stretchable Neural Interfaces: Yield, Resolution, and Recording/Stimulation of Neural Activity
AbstractA high-resolution elastically stretchable microelectrode array (SMEA) for interfacing with neural tissue is described. The SMEA consists of an elastomeric substrate, such as poly(dimethylsiloxane) (PDMS), elastically stretchable gold conductors, and an electrically insulating encapsulating layer in which contact holes are opened. We demonstrate the feasibility of producing contact holes with 40 μm × 40 μm openings, show why the adhesion of the encapsulation layer to the substrate is weakened during contact hole fabrication, and provide remedies. These improvements result in greatly increased fabrication yield and reproducibility. An SMEA with 28 microelectrodes was fabricated. The contact holes (100 μm × 100 μm) in the encapsulation layer are only ∼10% the size of the previous generation, allowing a larger number of microelectrodes per unit area, thus affording the capability to interface with a smaller neural population per electrode. This new SMEA is used to record spontaneous and evoked activity in organotypic hippocampal tissue slices at 0% strain before stretching, at 5% and 10% equibiaxial strain, and again at 0% strain after relaxation. Stimulus–response curves at each strain level are measured. The SMEA shows excellent biocompatibility for at least two weeks.  Spontaneous and evoked neural activity of a hippocampal tissue slice are recorded using a high-resolution stretchable microelectrode array (SMEA). The SMEA is capable of recording and stimulating neural activity at large biaxial strains and completely recovers after relaxation.
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Three-Dimensional Kelvin Probe Microscopy for Characterizing In-Plane Piezoelectric Potential of Laterally Deflected ZnO Micro-/Nanowires
AbstractPotential characterization of deflected piezoelectric nanowires (NWs) is of great interest for current development of electromechanical nanogenerators that harvest ambient mechanical energy. In this paper, a Kelvin probe microscopy (KPM) technique hybridizing scanning KPM (SKPM) with atomic force microscope (AFM) surface-approach spectroscopy methods for characterizing in-plane piezoelectric potential of ZnO microwires (MWs) is presented. This technique decouples the scanning motion of the AFM tip from sample topography, and thus effectively eliminates artifacts induced by high topographical variations along the edges of MWs/NWs which make characterization by conventional SKPM inappropriate or impossible. By virtue of the topography/tip motion decoupling approach, the electrical potential can also be mapped in a three-dimensional (3D) spatial volume above the sample surface. Therefore, this technique is named 3DKPM. Through 3DKPM mapping, the piezopotential generated by a laterally deflected ZnO MW was determined by extracting the potential asymmetry from opposite sides of the MW. The measurement results agree well with theoretical predictions. Integrating an external bias to the MW sample allowed direct observation of piezopotential and carrier concentration coupling phenomenon in ZnO, opening a door toward quantitative microscopic investigation of the piezotronic effect. With further positioning refinements, 3DKPM could become a powerful technique for the characterization of piezoelectric potential and related effects in micro/nanostructures of high topographical variations, as well as development of MW/NW-based piezoelectric nanodevices.  Direct measurement of the piezoelectric voltage generated by a single ZnO microwire under bending strain is achieved with a novel three-dimensional Kelvin probe microscopy (3DKPM) technique, which eliminates measurement artifacts associated with discontinuous sample topography (e.g., at edges of micro-/nanowires). 3DKPM is applied to observe piezoelectric–semiconductor property coupling in ZnO and detect peak piezoelectric voltage of at least 600 mV from a single microwire.
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Photoconductive Hybrid Films via Directional Self-Assembly of C60 on Aligned Carbon Nanotubes
AbstractHybrid nanostructured materials can exhibit different properties than their constituent components, and can enable decoupled engineering of energy conversion and transport functions. Novel means of building hybrid assemblies of crystalline C60 and carbon nanotubes (CNTs) are presented, wherein aligned CNT films direct the crystallization and orientation of C60 rods from solution. In these hybrid films, the C60 rods are oriented parallel to the direction of the CNTs throughout the thickness of the film. High-resolution imaging shows that the crystals incorporate CNTs during growth, yet grazing-incidence X-ray diffraction (GIXD) shows that the crystal structure of the C60 rods is not perturbed by the CNTs. Growth kinetics of the C60 rods are enhanced 8-fold on CNTs compared to bare Si, emphasizing the importance of the aligned, porous morphology of the CNT films as well as the selective surface interactions between C60 and CNTs. Finally, it is shown how hybrid C60–CNT films can be integrated electrically and employed as UV detectors with a high photoconductive gain and a responsivity of 105 A W−1 at low biases (± 0.5 V). The finding that CNTs can induce rapid, directional crystallization of molecules from solution may have broader implications to the science and applications of crystal growth, such as for inorganic nanocrystals, proteins, and synthetic polymers.  Aligned carbon nanotube (CNT) films cause rapid, directional crystallization of C60 rods from solution, resulting in hybrid structures where the C60 rods incorporate CNTs during growth and are oriented parallel to the direction of the CNTs. The hybrid sheets are integrated electrically and employed as UV detectors with high photoconductive gain (responsivity as high as 105 A W−1 at low biases (±0.5 V)).
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Engineering of Complex Macroporous Materials Through Controlled Electrodeposition in Colloidal Superstructures
AbstractMacroporous materials with a sophisticated architecture are obtained by electrochemical deposition of gold or polypyrrole in colloidal-crystal templates. The Langmuir–Blodgett technique enables assembly of sub-micrometric silica-particle monolayers on conductive gold substrates, thus leading to colloidal superstructures with an unprecedented control of their features at the single-bead-layer level. This allows the integration of deliberate planar defects or the elaboration of well-defined gradients in terms of sphere size. Controlled infiltration using electrochemical deposition preserves the architecture of the original templates and leads to inverse opals with well-defined pore structures after the removal of the inorganic particles.  Complex macroporous architectures made of gold or polypyrrole are obtained by using the Langmuir–Blodgett technique to assemble colloidal superstructures as templates. Porosity gradients can be synthesized with control of the pore size at the single-pore-layer level. The obtained materials present interesting features that open up potential applications ranging from electrochemistry to photonics.
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Efficient Polymer Solar Cells Based on Poly(3-hexylthiophene):Indene-C70 Bisadduct with a MoO3 Buffer Layer
AbstractPolymer solar cells (PSCs) with poly(3-hexylthiophene) (P3HT) as a donor, an indene-C70 bisadduct (IC70BA) as an acceptor, a layer of indium tin oxide modified by MoO3 as a positive electrode, and Ca/Al as a negative electrode are presented. The photovoltaic performance of the PSCs was optimized by controlling spin-coating time (solvent annealing time) and thermal annealing, and the effect of the spin-coating times on absorption spectra, X-ray diffraction patterns, and transmission electron microscopy images of P3HT/IC70BA blend films were systematically investigated. Optimized PSCs were obtained from P3HT/IC70BA (1:1, w/w), which exhibited a high power conversion efficiency of 6.68%. The excellent performance of the PSCs is attributed to the higher crystallinity of P3HT and better a donor–acceptor interpenetrating network of the active layer prepared under the optimized conditions. In addition, PSCs with a poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) buffer layer under the same optimized conditions showed a PCE of 6.20%. The results indicate that the MoO3 buffer layer in the PSCs based on P3HT/IC70BA is superior to that of the PEDOT:PSS buffer layer, not only showing a higher device stability but also resulting in a better photovoltaic performance of the PSCs.  The power conversion efficiency of polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) as a donor and an indene-C70 bisadduct (IC70BA) as an acceptor with MoO3-modified indium tin oxide as a positive electrode reaches 6.68% at the optimized ratio of P3HT/IC70BA = 1:1 (w/w). The photovoltaic performance of the PSCs is optimized by controlling spin-coating time (solvent annealing time) and thermal annealing.
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Ionic Current Rectification in Soft-Matter Diodes with Liquid-Metal Electrodes
AbstractA soft-matter-based diode composed of hydrogel and liquid metal (eutectic gallium indium, EGaIn) is presented. The ability to control the thickness, and thus resistivity, of an oxide skin on the metal enables rectification. First, a simple model system with liquid-metal/electrolyte-solution/Pt interfaces is characterized. The electrically insulating oxide skin on the EGaIn electrode is reduced or oxidized further depending on the direction of the bias, thereby allowing unidirectional ionic current. The forward current of the diode increases as the conductivity of the electrolyte increases, whereas backward current depends on the pH of the medium in contact with the insulating oxide layer on the EGaIn electrode. As a result, the diode shows a higher rectification ratio (defined as the ratio of forward to backward current measured at the same absolute bias) with more conductive electrolyte at neutral pH. Replacement of the liquid electrolyte solution with a hydrogel improves the structural stability of the soft diode. The rectification performance also improves due to the increased ionic conductivity by the gel. Finally, a diode composed entirely of soft materials by replacing the platinum electrode with a second liquid-metal electrode is presented. Contacting each liquid metal with a polyelectrolyte gel featuring different pH values provided asymmetry in the device, which is necessary for rectification. A hydrogel layer infused with a strong basic polyelectrolyte removes the insulating oxide layer, allowing one interface with the EGaIn electrode to be conductive regardless of the direction of bias. Thus, the oxide layer at the other interface rectifies the current.  A soft-matter diode composed of hydrogel and a gallium-based liquid metal is reported. The thickness of an insulating oxide skin on the liquid metal electrode depends on the direction of the bias and can be harnessed to produce ionic current rectification. The rectification behavior is a function of the environment in the hydrogel including the local pH and the ionic conductivity. Such principles could be used in new generations of soft and biocompatible devices.
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Functionalization of Nanostructured Hematite Thin-Film Electrodes with the Light-Harvesting Membrane Protein C-Phycocyanin Yields an Enhanced Photocurrent
AbstractThe integration of light-harvesting proteins and other photosynthetic molecular machinery with semiconductor surfaces plays an important role in improving their performance as solar-cell materials. Phycocyanin is one such protein that can be employed for this purpose. Phycocyanins have light-harvesting properties and belong to the phycobilisome protein family. They are present in cyanobacteria, which capture light energy and funnel it to reaction centers during photosynthesis. Here, a way of increasing the photocurrent of hematite by covalent cross-coupling with phycocyanin is reported. For this, a hematite–phycocyanin integrated system is assembled by consecutive adsorption and cross-coupling of protein molecules, separated by an agarose layer and a linker molecule, on the top of a mesoporous hematite film. The hematite–phycocyanin assembly shows a two-fold increased photocurrent in comparison with pristine hematite film. The increase in the photocurrent is attributed to the enhanced light absorption of the hematite film after integration with the protein, as is evident from the UV–vis spectra and from the photocurrent-action spectrum. The assembly shows long-term stability and thus constitutes a promising hybrid photoanode for photo-electrochemical applications.  A hybrid integrated system constituting a hematite nanoparticulate film and a light-harvesting protein (C-phycocyanin) is developed. The system shows a two-fold increase in the photocurrent in comparison to the pristine hematite film. The system also shows enhanced efficiency in the visible region due to the light-harvesting action of the protein.
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Resolving the Three-Dimensional Microstructure of Polymer Electrolyte Fuel Cell Electrodes using Nanometer-Scale X-ray Computed Tomography
AbstractThe electrodes of a polymer electrolyte fuel cell (PEFC) are composite porous layers consisting of carbon and platinum nanoparticles and a polymer electrolyte binder. The proper composition and arrangement of these materials for fast reactant transport and high electrochemical activity is crucial to achieving high performance, long lifetimes, and low costs. Here, the microstructure of a PEFC electrode using nanometer-scale X-ray computed tomography (nano-CT) with a resolution of 50 nm is investigated. The nano-CT instrument obtains this resolution for the low-atomic-number catalyst support and binder using a combination of a Fresnel zone plate objective and Zernike phase contrast imaging. High-resolution, non-destructive imaging of the three-dimensional (3D) microstructures provides important new information on the size and form of the catalyst particle agglomerates and pore spaces. Transmission electron microscopy (TEM) and mercury intrusion porosimetry (MIP) is applied to evaluate the limits of the resolution and to verify the 3D reconstructions. The computational reconstructions and size distributions obtained with nano-CT can be used for evaluating electrode preparation, performing pore-scale simulations, and extracting effective morphological parameters for large-scale computational models.  The porous electrode of a polymer electrolyte fuel cell is imaged using X-ray computed tomography with a resolution of 50 nm, achieved using Zernike phase contrast. The three-dimensional reconstructions are validated against transmission electron microscopy and mercury intrusion porosimetry.
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White Organic Light-Emitting Diodes Based on Quench-Resistant Fluorescent Organophosphorus Dopants
AbstractThe control of the doping ratio of a blue-emitting matrix by an orange emitter with high accuracy still remains very challenging in the development of reproducible white organic light-emitting diodes (WOLEDs). In this work, the development of an organophosphorus dopant that presents a high doping rate in order to reach white emission is reported. The increase of the doping rate has a small impact on the CIE co-ordinates and on the EQE. These results are very appealing towards the development of “easy-to-make” WOLEDS.  The design of advancedorganophosphorus dopants for a blue matrix, 4,4'-bis(2,2'-diphenylvinyl)biphenyl), affording organic light-emitting diodes presenting no change in the external quantum yield caused by an increase in the doping rate is reported. Moreover, white-emission is obtained for high doping rates varying over a large range, giving access to easily reproducible white organic light-emitting diodes.
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Yolk–Shell Hybrid Materials with a Periodic Mesoporous Organosilica Shell: Ideal Nanoreactors for Selective Alcohol Oxidation
AbstractThis contribution describes the preparation of multifunctional yolk–shell nanoparticles (YSNs) consisting of a core of silica spheres and an outer shell based on periodic mesoporous organosilica (PMO) with perpendicularly aligned mesoporous channels. The new yolk–shell hybrid materials were synthesised through a dual mesophase and vesicle soft templating method. The mesostructure of the shell, the dimension of the hollow space (4∼52 nm), and the shell thickness (16∼34 nm) could be adjusted by precise tuning of the synthesis parameters, as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption investigations. Various metal nanoparticles (e.g., Au, Pt, and Pd) were encapsulated and confined in the void space between the core and the shell using impregnation and reduction of adequate metal precursors. The selective oxidation of various alcohol substrates was then carried out to illustrate the benefits of such an architecture in catalysis. High conversion (∼100%) and excellent selectivity (∼99%) were obtained over Pd nanoparticles encapsulated in the hybrid PMO yolk–shell structures.  Yolk–shell-structured metal (Au, Pt, Pd) catalysts with periodic mesoporous organosilica (PMO) shells and tunable void space and shell thickness are synthesized by a simple soft templating method. The Pd-loaded hybrid yolk–shell PMO catalysts exhibit high catalytic activities (≈100% conversions) and selectivity (≈99%) in various selective oxidation reaction of alcohol in aqueous conditions.
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Multi-addressable photochromic terarylene containing benzo[b]thiophene-1,1-dioxide unit as ethene bridge: multifunctional molecular logic gates on unimolecular platform
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14973G, Paper Shangjun Chen, Yuheng Yang, Yue Wu, He Tian, Weihong Zhu
A novel photochromic terarylene BTO allows access to multiple states triggered by metal ions, protons and light, specifically for constructing multifunctional molecular logic gates on the unimolecular platform.
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A highly efficient dye-sensitized solar cell with a platinum nanoflowers counter electrode
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14623A, Paper Tien-Lin Hsieh, Hsin-Wei Chen, Chung-Wei Kung, Chun-Chieh Wang, R. Vittal, Kuo-Chuan Ho
Platinum nanoflowers were synthesized by pulse reversal electrodeposition on conducting glass and applied to the counter electrode of a dye-sensitized solar cell to achieve a high efficiency of 8.13%.
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Topological loading of Cu(I) catalysts onto crystalline cellulose nanofibrils for the Huisgen click reaction
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15661J, Paper Hirotaka Koga, Akihiro Azetsu, Eriko Tokunaga, Tsuguyuki Saito, Akira Isogai, Takuya Kitaoka
Highly dispersed and exposed Cu(I) catalysts were topologically loaded over the crystalline surfaces of cellulose nanofibrils for the Huisgen reaction.
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Solvent and polymer matrix effects on TIPS-pentacene/polymer blend organic field-effect transistors
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16487F, Paper Do Kyung Hwang, Canek Fuentes-Hernandez, John D. Berrigan, Yunnan Fang, Jungbae Kim, William J. Potscavage, Hyeunseok Cheun, Kenneth H. Sandhage, Bernard Kippelen
The effects of solvent and polymer matrix selection on the phase segregation behavior of TIPS-pentacene/polymer blend films, and on the resulting device performance, are evaluated.
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Discovery and Evaluation of a Single Source Selenium Sulfide Precursor for the Synthesis of Alloy PbSxSe1-x Nanocrystals
J. Mater. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2JM30408B, Paper Geoffrey Ozin, Jordan William Thomson, Xiang Wang, Laura Hoch, Daniel O Faulkner, Srebri Petrov
In this article, we evaluate the use of a novel single source SemSn precursor for the synthesis of alloy PbSxSe1-x nanocrystals using oleylamine as stabilizing ligand, reagent and solvent. The...
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Synthesis of chitosan-coated near-infrared layered double hydroxide nanoparticles for in vivo optical imaging
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16447G, Paper Pei-Ru Wei, Shih-Hsun Cheng, Wei-Neng Liao, Kun-Che Kao, Ching-Feng Weng, Chia-Hung Lee
The chitosan-coated layered double hydroxide nanoparticles (LDHs)-indocyanine green samples have a high potential for the development of both organ-specific drug delivery systems and in vivo contrast agents for clinical cancer diagnosis and chemotherapy. LDHs coated with different amounts of chitosan showed a specific accumulation of nanoparticles in different target organs when injected intravenously.
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Iron supported C@Fe3O4 nanotube array: a new type of 3D anode with low-cost for high performance lithium-ion batteries
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15955D, Paper Keyu Xie, Zhouguang Lu, Haitao Huang, Wei Lu, Yanqing Lai, Jie Li, Limin Zhou, Yexiang Liu
Iron supported C@Fe3O4 nanotube array is used as a novel type of 3D anode for lithium-ion batteries, showing attractive electrochemical performance.
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Enhanced n-type thermopower in distortion-free LiMn2O4
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16297K, Communication Taylor D. Sparks, Aleksander Gurlo, David R. Clarke
Enhanced n-type thermopower of -73 [small mu ]V K-1 is reported for Jahn-Teller distortion free LiMn2O4 due to an increased electronic degeneracy ratio.
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A novel approach to electrospinning of pristine and aligned MEH-PPV using binary solvents
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15970H, Paper Wei Zhong, Fan Li, Lie Chen, Yiwang Chen, Yen Wei
Continuous electrospinning of pristine and aligned MEH-PPV in binary solvents without adding a polymer or a surfactant has been demonstrated. Polarization anisotropy spectra of aligned electrospun fibers indicated preferential alignment of MEH-PPV along the electrospun fiber axis. Electrospun fibers of MEH-PPV/PCL had higher polarization anisotropy than aligned pristine MEH-PPV at emission peak.
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Sulfated graphene as an efficient solid catalyst for acid-catalyzed liquid reactions
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16608A, Paper Fujian Liu, Jing Sun, Longfeng Zhu, Xiangju Meng, Chenze Qi, Feng-Shou Xiao
Compared with conventional SO3H-functionalized ordered mesoporous carbons and silicas, G-SO3H is a highly active, very stable, and excellently recyclable catalyst, which may be attributed to its unique graphene structure and there is almost no limitation of mass transfer for acid-catalyzed liquid reactions.
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Inkjet-printed graphene-PEDOT:PSS modified screen printed carbon electrode for biochemical sensing
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14005E, Paper Chakrit Sriprachuabwong, Chanpen Karuwan, Anurat Wisitsorrat, Ditsayut Phokharatkul, Tanom Lomas, Pornpimol Sritongkham, Adisorn Tuantranont
A novel method for electrode modification based on inkjet-printing of electrochemically synthesized graphene-PEDOT:PSS nanocomposite is reported for the first time. The method results in significantly enhanced electrode's biochemical sensing responses.
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Electrodeposition of luminescent composite metal coatings containing rare-earth phosphor particles
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM13925A, Paper Murugan Ganapathi, Svetlana V. Eliseeva, Neil R. Brooks, Dimitri Soccol, Jan Fransaer, Koen Binnemans
Luminescent metal coatings incorporating red, yellow, green or blue rare-earth phosphor particles were prepared by electrodeposition from a non-aqueous electrolyte.
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[2 + 2] Cycloadditions onto graphene
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15454D, Paper Pablo A. Denis, Federico Iribarne
Herein, we study [2 + 2] cycloadditions reactions onto graphene. We have found that owing to stacking, CH-[small pi] interactions and steric hindrance existing between the aromatic rings, the addition of benzyne molecules follows a characteristic pattern.
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Effects of direct solvent exposure on the nanoscale morphologies and electrical characteristics of PCBM-based transistors and photovoltaics
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15260F, Paper Sooji Nam, Jaeyoung Jang, Hyojung Cha, Jihun Hwang, Tae Kyu An, Seonuk Park, Chan Eon Park
The optimal phase separation in the P3HT/PCBM films was obtained simply by direct exposure of solvents for a few seconds.
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Nematic Phases in 1,2,4-Oxadiazole-Based Bent-Core Liquid Crystals: Is There a Ferroelectric Switching?
AbstractFour series of new 1,2,4-oxadiazole derived bent-core liquid crystals incorporating one or two cyclohexane rings are synthesized and investigated by optical polarizing microscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), electro-optical, and dielectric investigations. All the compounds exhibit wide ranges of nematic phases composed of tilted smectic (SmC-type) cybotactic clusters with strongly tilted aromatic cores (40–57°) and show a distinct peak in the current curves observed under a triangular wave field. Dielectric spectroscopy of aligned samples corroborates the previously proposed polar structure of the cybotactic clusters and the ferroelectric-like polar switching of these nematic phases. Hence, it is shown that this is a general feature of the nematic phases of structurally different 3,5-diphenyl-1,2,4-oxadiazole derivatives. In these uniaxial nematic phases there is appreciable local biaxiality and polar order in the cybotactic clusters. As a second point it is shown that electric field induced fan-like textures, as often observed for the nematic phases of bent-core liquid crystals, do not indicate the formation of a smectic phase, rather they represent special electro-convection patterns due to hydrodynamic instabilities.  1,2,4-Oxadiazole-derived bent-core liquid crystals incorporating one or two cyclohexane rings form nematic phases composed of cybotactic clusters that show ferroelectric-like polar switching and electric field induced fan-like textures, representing special electro-convection patterns.
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Osteophilic Multilayer Coatings for Accelerated Bone Tissue Growth
Osteophilic modular nanostructured multilayers containing hydroxyapatite nanoparticles complexed with a natural polymer chitosan create an osteoconductive surface for mesenchymal stem cells (MSCs). Coupled with the sustained release of physiological amounts of osteoinductive bone morphogenetic protein over several days from degradable poly(β-amino ester) based multilayers, this single coating results in a synergistic accelerated and upregulated differentiation of MSCs into osteoblasts laying down new bone tissue on orthopedic implants.
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Functional Polysaccharide Composite Nanoparticles from Cellulose Acetate and Potential Applications
AbstractAn in situ technique for preparing composite nanoparticles from hydrophobic cellulose acetate and hydrophilic polysaccharides using nanoprecipitation is presented. This technique allows the nanoparticles’ surface properties to be tuned very specifically. Spherical, narrow-size-distributed composite nanoparticles of different size, charge, functionality, and increased stability can be generated by using hydroxyethyl cellulose, carboxymethyl cellulose, low molecular weight chitosan, and amino cellulose. The influence of the pH and hydrophilic polysaccharide content in the particle formation is shown. The pH- and ionic strength- effective zeta-potential functions are evidence of the presence of functional polysaccharides at the nanoparticle surface. The in situ technique is compared with the adsorption of hydrophilic polysaccharides onto cellulose acetate nanoparticles in two steps. The great potential of in situ prepared composite nanoparticles in the pharmaceutical industry and bio- or food technology, as carriers of hydrophobic substances in aqueous media and for specific surface modifications, e.g., to selectively introduce strong antimicrobial properties, is illustrated.  Composite nanoparticles from cellulose acetate and a hydrophilic polysaccharide are prepared in situ using a nanoprecipitation technique. Hydrophilic polysaccharides of different charge and functionality can be applied, which allow very specific modification of the nanoparticle surfaces. The composite nanoparticles can be used for solubilizing hydrophobic compounds in an aqueous environment and for the nanostructuring of surfaces in order to introduce strong antimicrobial activities.
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Phenylcarbazole-dipyridyl triazole hybrid as bipolar host material for phosphorescent OLEDs
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15963E, Paper Wen-Yi Hung, Guan-Min Tu, Shou-Wei Chen, Yun Chi
Two bipolar host materials p-cbtz and m-cbtz were utilized as common hosts for phosphorescent OLEDs with high efficiencies and low efficiency roll-off.
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Narrowing band gap of platinum acetylide dye-sensitized solar cell sensitizers with thiophene [small pi]-bridges
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15928G, Paper Wenjun Wu, Jing Zhang, Haibo Yang, Bin Jin, Yue Hu, Jianli Hua, Chao Jing, Yitao Long, He Tian
Here we report the synthesis of three new linear structure platinum sensitizers incorporating different thiophene groups and their photovoltaic performance in DSSCs.
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Transition between widened BPs by light irradiation using photo-active bent-core liquid crystal with chiral dopant
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16650J, Communication Hyeon-Cheol Jeong, Khoa V. Le, Min-Jun Gim, Sung-Taek Hur, Suk-Won Choi, Fumito Araoka, Ken Ishikawa, Hideo Takezoe
Under UV light irradiation of an optically active bent-core nematogen containing a chiral dopant, BPI changes to BPIII. During this process crack-like texture is observed particularly in green platelets. This phenomenon is attributed to the deformation of the cubic lattice due to trans-cis isomerization.
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Thermal curing of PBI membranes for high temperature PEM fuel cells
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14774B, Paper David Aili, Lars N. Cleemann, Qingfeng Li, Jens Oluf Jensen, Erik Christensen, Niels J. Bjerrum
Thermal treatment was used to irreversibly cure PBI membranes and to convert the material from a thermoplastic polymer to a thermoset resin. Under a 2000 hour steady state operation fuel cell test at 160 [degree]C and at a high current load of 600 mA cm-2, the MEA based on cured PBI showed a performance decay rate of 43 [small mu ]V h-1, which should be compared with 308 [small mu ]V h-1 for the MEA based on its non-cured counterpart.
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Functional self-assembled monolayers (SAMs) of organic compounds on gold nanoparticles
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14239B, Highlight Sushilkumar A. Jadhav
Nanostructures of gold such as gold nanoparticles (AuNPs) or monolayer protected clusters (MPCs) can be functionalized with various organic groups by chemisorption of bifunctional organic compounds on them; nanoparticles bearing organic functional groups undergo chemical reactions like organic compounds.
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Cyclotricatechylene based porous crystalline material: Synthesis and applications in gas storage
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15159F, Paper Jin-Tao Yu, Zhe Chen, Junliang Sun, Zhi-Tang Huang, Qi-Yu Zheng
An undulated 2-D CTC-based covalent organic framework was prepared, the bowl-shaped core unit led to larger surface area and higher H2 uptake.
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Role of transition metal oxides in charge recombination layer used in tandem organic photovoltaic cells
J. Mater. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2JM30272A, Paper Yanqing Li, Jianxin Tang
The mechanism of charge recombination in transition metal oxide-based interconnector for tandem organic photovoltaic cells is investigated, where the interconnector is composed of an abrupt heterointerface between a Mg-doped 4,7-diphenyl-1,10-phenanthroline...
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Molecular dynamics simulations of the solvent- and thermal history-dependent structure of the PCBM fullerene derivative
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16142G, Paper Francesco Frigerio, Mose Casalegno, Chiara Carbonera, Tommaso Nicolini, Stefano Valdo Meille, Guido Raos
Molecular dynamics simulations elucidate the intermolecular organization within the crystalline and amorphous phases of the PCBM fullerene derivative.
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Energetic salts based on nitroiminotetrazole-containing acetic acid
J. Mater. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2JM30322A, Paper J M Shreeve, Young-Hyuk Joo, Haixiang Gao, Damon A. Parrish, Soo Gyeong Cho, Eun Mee Goh
2-(5-Nitroiminotetrazol-1-yl)acetic acid (4) was synthesized from 100% nitric acid and ethyl 2-(5-aminotetrazol-1-yl)acetate (2), which was easily obtained by reaction of ethyl aminoacetate hydrochloride, sodium hydroxide, and cyanogen azide. Compound 4...
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Size and shape matter! A multiscale molecular simulation approach to polymer nanocomposites
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15763B, Paper Radovan Toth, Francesca Santese, Simao P. Pereira, Daniel R. Nieto, Sabrina Pricl, Maurizio Fermeglia, Paola Posocco
This paper presents the development and application of a multiscale molecular modelling procedure for the estimation of thermophysical properties of polymer nanocomposites.
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Porphyrin containing light-responsive capsules for controlled drug release
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16702F, Communication Cao Li, Ze-Yong Li, Jing Zhang, Kang Wang, Yu-Hui Gong, Guo-Feng Luo, Ren-Xi Zhuo, Xian-Zheng Zhang
Porphyrin containing light-responsive capsules were fabricated via Layer-by-Layer assembly and the capsules could degrade and release the model drug FITC-Dex with light illumination.
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New full-color-emitting phosphor, Eu2+-doped Na2-xAl2-xSixO4 (0 [less-than-or-equal] x [less-than-or-equal] 1), obtained using phase transitions for solid-state white lighting
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15501J, Paper Ji Yeon Han, Won Bin Im, Donghyuk Kim, Sang Hoon Cheong, Ga-yeon Lee, Duk Young Jeon
A new color-tunable Eu2+-doped sodium aluminium silicate, Na2-xAl2-xSixO4 (0 [less-than-or-equal] x [less-than-or-equal] 1), phosphor system and dependency of its photoluminescence on the three different crystal structures (x value).
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Probing the adsorption performance of the hybrid porous MIL-68(Al): a synergic combination of experimental and modelling tools
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15609A, Paper Qingyuan Yang, Sebastien Vaesen, Muthusamy Vishnuvarthan, Florence Ragon, Christian Serre, Alexandre Vimont, Marco Daturi, Guy De Weireld, Guillaume Maurin
This work shows the triangular pores in the MIL-68(Al) solid are accessible and amino functionalization can enhance its separation performance.
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Luminescence characteristics and site-occupancy of Eu2+- and Eu3+-doped MgZn2(PO4)2 phosphors
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16352G, Paper Chuanyan Xu, Yadong Li, Yanlin Huang, Young Moon Yu, Hyo Jin Seo
Eu2+ ions occupy both Mg2+ and Zn2+ sites in MgZn2(PO4)2:Eu2+, and the occupancy on Zn2+ sites is dominant. However, Eu3+ ions are only distributed on the octahedral Mg2+ sites in MgZn2(PO4)2:Eu3+.
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Correlating Structure with Function in Thermally Annealed PCDTBT:PC70BM Photovoltaic Blends
AbstractA range of optical probes are used to study the nanoscale-structure and electronic-functionality of a photovoltaic-applicable blend of the carbazole co-polymer poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) and the electronic accepting fullerene derivative (6,6)-phenyl C70-butyric acid methyl ester (PC70BM). In particular, it is shown that the glass transition temperature of a PCDTBT:PC70BM blend thin-film is not sensitive to the relative blend-ratio or film thickness (at 1:4 blending ratio), but is sensitive to casting solvent and the type of substrate on which it is deposited. It is found that the glass transition temperature of the blend reduces on annealing; an observation consistent with disruption of π–π stacking between PCDTBT molecules. Reduced π–π stacking is correlated with reduced hole-mobility in thermally annealed films. It is suggested that this explains the failure of such annealing protocols to substantially improve device-efficiency. The annealing studies demonstrate that the blend only undergoes coarse phase-separation when annealed at or above 155 °C, suggesting a promising degree of morphological stability of PCDTBT:PC70BM blends.  In poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) :(6,6)-phenyl C70-butyric acid methyl ester (PC70BM) photovoltaic thin-films, the glass transition temperature is not sensitive to the relative blend-ratio or film thickness, but is sensitive to thermal treatment, casting solvent, and substrate. The π–π stacking between PCDTBT reduces upon thermal annealing, an observation that is correlate with reduced hole-mobility in thermally annealed devices. Coarse phase-separation in PCDTBT:PC70BM occurs upon annealing at or above 155 °C.
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Colorimetric Detection of Warfare Gases by Polydiacetylenes Toward Equipment-Free Detection
AbstractRationally designed polydiacetylene (PDA) molecules have been developed for rapid, selective, sensitive, and convenient colorimetric detection of organophosphate (OP) nerve agents, a mass destruction weapon. Oxime (OX) functionality was incorporated into diacetylene molecules to utilize its strong affinity toward organophosphates. The diacetylene molecules having an OX functional group (OX-PDA) were self-assembled to form PDA liposomes in an aqueous solution. Upon exposure to organophosphate nerve agent simulants, OX at the OX-PDA liposome surface interacts with nerve agent simulants, which results in intraliposomal repulsive stress due to steric repulsion between OP-occupied OX units at the liposome surface as well as interliposomal aggregation induced by increased hydrophobicity of the liposome surface via OP-OX complex formation. The resulting intra- and interliposomal stress causes disturbance of the conjugated backbone of OX-PDA, producing color change as a label-free and sensitive sensory signal. The effects of molecular structure on selectivity and sensitivity of OX-PDA liposome solution, OX-PDA liposome-embedded agarose gels, and OX-PDA liposome-coated cellulose acetate membranes were systematically investigated. The optimized OX-PDA liposome in the solid state showed selective and rapid optical transition upon exposure down to 160 ppb of diisopropylfluorophosphate (DFP), a nerve agent simulant. The results provide an insightful molecular design principle of PDA-based colorimetric sensor and suggest portable sensory patches for rapid, selective, sensitive, and convenient colorimetric detection of organophosphate nerve agents.  Polydiacetylene (PDA) liposomes having oxime (OX) functionality are rationally designed and synthesized to selectively and sensitively detect organophosphate (OP) nerve agents. Solutions, gel-pads, and solid films of OX-PDA liposome demonstrate convenient, rapid, selective, and sensitive colorimetric detection of nerve agent simulants through intra-liposomal repulsion and interliposomal hydrophobic aggregation.
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Luminescent Metal-Organic Frameworks for Selectively Sensing Nitric Oxide in an Aqueous Solution and in Living Cells
AbstractCu2+-based metal-organic framework (Cu−TCA) (H3TCA = tricarboxytriphenyl amine) having triphenylamine emitters was assembled and structurally characterized. Cu−TCA features a three-dimensional porous structure consolidated by the well-established Cu2(O2CR)4 paddlewheel units with volume of the cavities approximately 4000 nm3. Having paramagnetic Cu2+ ions to quench the luminescence of triphenylamine, Cu−TCA only exhibited very weak emission at 430 nm; upon the addition of NO up to 0.1 mM, the luminescence was recovered directly and provided about 700-fold fluorescent enhancement. The luminescence detection exhibited high selectivity – other reactive species present in biological systems, including H2O2, NO3−, NO2−, ONOO−, ClO− and 1O2, did not interfere with the NO detection. The brightness of the emission of Cu−TCA also led to its successful application in the biological imaging of NO in living cells. As a comparison, lanthanide metal-organic framework Eu−TCA having triphenylamine emitters and characteristic europium emitters was also assembled. Eu−TCA exhibited ratiometric fluorescent responses towards NO with the europium luminescence maintained as the internal standard and the triphenylamine emission exhibited more than 1000-fold enhancement.  A new metal-organic framework (MOF)-based luminescence NO chemosensor with triphenylamine blue emitters is consolidated by the well-established Cu2(O2CR)4 paddlewheel units and successfully applied in luminescene detection of NO in aqueous solution and bioimaging of NO in living cells. The quenched triphenylamine-based emission is recovered upon encapsulating NO directly. The sensor exhibits excellent selectivity for NO over other reactive species in biological systems.
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Controlled Synthesis of 3D Multi-Compartmental Particles with Centrifuge-Based Microdroplet Formation from a Multi-Barrelled Capillary
Controlled synthesis of micro multi-compartmental particles using a centrifuge droplet shooting device (CDSD) is reported. Sodium alginate solutions introduced in a multi-barreled capillary form droplets at the capillary orifice under ultrahigh gravity and gelify in a CaCl2 solution. The size, shape, and compartmentalization of the particles are controlled. Co-encapsulation of Jurkat cells and magnetic colloids into Janus particles is demonstrated. The Janus particles present sensitive reaction toward magnetic fields, while the viability of the encapsulated cells is 91%.
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Photochemical Disruption of Polyelectrolyte Multilayers
Photoreactive polyelectrolyte multilayers (PEMs) that dissolve upon UV irradiation are described. Light-induced switching of the formal charge of a photoreactive polycation resulted in repulsive interlayer electrostatic forces, and caused the dissolution of PEM films. Combining both photoreactive and inert polycations in the same film yielded additional control over the light-induced change in film thickness.
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Silaindacenodithiophene-Based Low Band Gap Polymers – The Effect of Fluorine Substitution on Device Performances and Film Morphologies
AbstractSilaindacenodithiophene is copolymerized with benzo[c][1,2,5]thiadiazole (BT) and 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT), respectively their fluorinated counter parts 5,6-difluorobenzo[c][1,2,5]thiadiazole (2FBT) and 5,6-difluoro-4,7-di(thiophen-2-yl) benzo[c][1,2,5]thiadiazole (2FDTBT). The influence of the thienyl spacers and fluorine atoms on molecular packing and active layer morphology is investigated with regard to device performances. bulk heterojunction (BHJ) solar cells based on silaindacenodithiophene donor-acceptor polymers achieved PCE's of 4.5% and hole mobilities of as high as 0.28 cm2/(V s) are achieved in an organic field-effect transistor (OFET).  Fluorine is introduced into silaindacenodithiophene based semiconducting polymers with the aim to improve the photovoltaic as well as the charge carrier properties. The influence of the thienyl spacers and fluorine atoms on molecular packing and active layer morphology of the new polymers is investigated with regard to device performance.
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Organic Dye Design Tools for Efficient Photocurrent Generation in Dye-Sensitized Solar Cells: Exciton Binding Energy and Electron Acceptors
AbstractThe relationship between the exciton binding energies of several pure organic dyes and their chemical structures is explored using density functional theory calculations in order to optimize the molecular design in terms of the light-to-electric energy-conversion efficiency in dye-sensitized solar cell devices. Comparing calculations with measurements reveals that the exciton binding energy and quantum yield are inversely correlated, implying that dyes with lower exciton binding energy produce electric current from the absorbed photons more efficiently. When a strong electron-accepting moiety is inserted in the middle of the dye framework, the light-to-electric energy-conversion behavior significantly deteriorates. As verified by electronic-structure calculations, this is likely due to electron localization near the electron-deficient group. The combined computational and experimental design approach provides insight into the functioning of organic photosensitizing dyes for solar-cell applications. This is exemplified by the development of a novel, all-organic dye (EB-01) exhibiting a power conversion efficiency of over 9%.  A combined computational and experimental design approach provides insight into the functioning of organic photosensitizer dyes for solar cell applications. Comparing calculations with measurements reveals that the exciton binding energy and quantum yield are inversely correlated. When a strong electron-accepting moiety is inserted in the middle of the dye framework, the light-to-electric energy conversion behavior significantly deteriorates.
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Nanomaterials via Laser Ablation/Irradiation in Liquid: A Review
AbstractLaser ablation of solid targets in the liquid medium can be realized to fabricate nanostructures with various compositions (metals, alloys, oxides, carbides, hydroxides, etc.) and morphologies (nanoparticles, nanocubes, nanorods, nanocomposites, etc.). At the same time, the post laser irradiation of suspended nanomaterials can be applied to further modify their size, shape, and composition. Such fabrication and modification of nanomaterials in liquid based on laser irradiation has become a rapidly growing field. Compared to other, typically chemical, methods, laser ablation/irradiation in liquid (LAL) is a simple and “green” technique that normally operates in water or organic liquids under ambient conditions. Recently, the LAL has been elaborately developed to prepare a series of nanomaterials with special morphologies, microstructures and phases, and to achieve one-step formation of various functionalized nanostructures in the pursuit of novel properties and applications in optics, display, detection, and biological fields. The formation mechanisms and synthetic strategies based on LAL are systematically analyzed and the reported nanostructures derived from the unique characteristics of LAL are highlighted along with a review of their applications and future challenges.  Laser ablation of solid targets in liquid medium has been elaborately developed to prepare nanomaterials with special morphologies, microstructures, and to achieve one-step functionalization. The synthetic strategies based on laser ablation in liquid (LAL) are summarized and nanostructures derived from the peculiarity of LAL are highlighted along with a review of their applications and future challenges.
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One-Dimensional Organic Photonic Heterostructures: Rational Construction and Spatial Engineering of Excitonic Emission
Organic photonic heterostructures are constructed through a template-free self-assembly method. The host-guest intermolecular interactions play an essential role in the formation of various block orange-blue-orange and blue/green microtubes. The spatial distribution of excitons is engineered to investigate the excitonic behaviors in light propagation along the axial heterostructures. These results offer a new route to the integration of organic photonic building blocks for optical processing applications.
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Thermodynamic Imbalance, Surface Energy, and Segregation Reveal the True Origin of Nanotube Synthesis
Extensive analyses of thermodynamicimbalance, surface energy, and segregation of nanotubes on nanoparticle surfaces are performed. A model for surface energy i developed. In addition, nanotube growth both by vapor-phase and solid-phase mechanisms is described. Segregation of the nanotube species to the periphery of the nanoparticle, the creation of an amorphous shell at this periphery, a droplet created in this shell, and the mediation of this droplet for supersaturation and nucleation of the nanotube species may be the true causes of nanotube growth.
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Self-carbonized lamellar nano/micro hierarchical structure C/TiO2 and its Li-ion intercalation performance
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15400E, Paper Po-Chin Chen, Min-Chiao Tsai, Huang-Chin Chen, I-Nan Lin, Hwo-Shuenn Sheu, Yu-Sheng Lin, Jenq-Gong Duh, Hsin-Tien Chiu, Chi-Young Lee
Partial enlarged drawing of titanate (CT) with organic species inserted into the layers and two different procedures for forming C/TiO2 composites (with and without precursor).
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Layer-by-layer assembled enzyme multilayers with adjustable memory performance and low power consumption via molecular-level control
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16231H, Paper Hyunhee Baek, Chanwoo Lee, Jeongju Park, Younghoon Kim, Bonkee Koo, Hyunjung Shin, Dayang Wang, Jinhan Cho
We demonstrate that the redox enzymes can be used as electrically active materials for nonvolatile memory devices and that, furthermore their switching behavior originates from redox sites within enzymes.
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Multicolor light emitters based on energy exchange between Tb and Eu ions co-doped into ultrasmall [small beta]-NaYF4 nanocrystals
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15785C, Paper Artur Podhorodecki, Mateusz Banski, Jan Misiewicz, Mohammad Afzaal, Paul O'Brien, Dongkyu Cha, Xianbin Wang
Relaxation mechanisms in ultrasmall NaYF4 nanocrystals doped by Tb and Eu ions are discussed on the basis of their excitation mechanism. The lifetime dependence vs. the excitation energy for such a system is also reported for the first time.
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Unconventional methods for fabricating nanostructures toward high-fidelity sensors
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16568F, Feature Article Su Yeon Lee, Hwan Chul Jeon, Seung-Man Yang
Plasmonic materials fabricated by using a precisely controlled method show promising platforms for developing high-sensitivity sensing devices. This Feature Article reviews recent advances in the fabrication methods and features of plasmonic nanostructures, and outlines their use in practical sensing devices.
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Heterojunction with organic thin layer for three dimensional high performance hybrid solar cells
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15674A, Paper Fute Zhang, Xiaoyuan Han, Shuit-tong Lee, Baoquan Sun
A hybrid solar cell with power conversion efficiency of 9.2% was achieved based on the core (silicon)-shell poly(3-hexylthiophene) heterojunction.
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Functionalized cyano-OPVs as melt-processable two-photon absorbers
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15846A, Paper Brian T. Makowski, Joseph Lott, Brent Valle, Kenneth D. Singer, Christoph Weder
Cyano-functionalized oligo(phenylenevinylene) dyes, which have the propensity to form excimers, were chemically modified with the objective to simultaneously maximize the two-photon absorption cross-section, melt-processability, and solubility.
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Conducting polymer/carbon nanocoil composite electrodes for efficient supercapacitors
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15740C, Paper R. B. Rakhi, Wei Chen, H. N. Alshareef
The study demonstrates the use of conducting polymer coated carbon nanocoils as binder free electrode materials for symmetric supercapacitors with high specific capacitances of 360 and 202 F g-1 respectively for PANI/CNCs and PPY/CNCs.
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Direct methanol oxidation at low overpotentials using Pt nanoparticles electrodeposited at ultrathin conductive RuO2 nanoskins
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15553B, Paper Jeremy J. Pietron, Michael B. Pomfret, Christopher N. Chervin, Jeffrey W. Long, Debra R. Rolison
Scanning electron micrograph of Pt nanoparticles electrodeposited on a RuO2 nanoskin supported on Ti foil. The Pt/RuO2(Ti) foils catalyze the direct electrochemical oxidation of methanol at [similar]0.65 V vs. NHE in 0.1 M HClO4.
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[small pi]-Extended TTF: a versatile molecule for organic electronics
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15710A, Feature Article Fulvio G. Brunetti, Juan Luis Lopez, Carmen Atienza, Nazario Martin
The singular geometrical and electronic features of the butterfly shape electron-donor exTTF molecule have been critically analyzed in the so-called "organic electronics" at different molecular, macromolecular and supramolecular levels.
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Construction of magnetic visible-light-driven plasmonic Fe3O4@SiO2@AgCl : Ag nanophotocatalyst
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16622D, Paper Changhua An, Xijuan Ming, Jizhuang Wang, Shutao Wang
Magnetic visible-light-driven plasmonic Fe3O4@SiO2@AgCl : Ag nanophotocatalyst with high activity, stability and easy recoverability have been constructed by combining polyol, sol-gel and photochemical reduction methods.
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Nanoporous gold nanoparticles
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15727F, Paper Dong Wang, Peter Schaaf
We present a simple method to fabricate nanoporous gold nanoparticles (right image) from Au-Ag nanoparticles formed by dewetting with an ultra-high specific surface area.
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Pd(II) Nanoparticles in Porous Polystyrene: Factors Influencing the Nanoparticle Size and Catalytic Properties
J. Mater. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2JM30634D, Paper Irina B Tsvetkova, Valentina G Matveeva, Valentin Y Doluda, Alexei V Bykov, Alexander I Sidorov, Sergey V Schennikov, Michael G Sulman, Pyotr M Valetsky, Barry D Stein, Chun-Hsing Chen, Esther M Sulman, Lyudmila M Bronstein
In this paper for the first time we present a systematic study of the influence of hydrophobicity of Pd(II) compounds, (CH3CN)2PdCl2, (PhCN)2PdCl2, (Sty)(CH3CN)PdCl2, and (StyPdCl2)2, on nanoparticle (NP) formation in...
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Hierarchically Porous LiFePO4/Nitrogen-doped Carbon Nanotube Composite as Cathode for Lithium Ion Batteries
J. Mater. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2JM30380A, Paper Jinli Yang, Jiajun Wang, Xifei Li, Dongniu Wang, Jian Liu, Guoxian Liang, Michel Gauthier, Yongliang Li, Dongsheng Geng, Ruying Li, Xueliang Sun
A porous composite of LiFePO4/nitrogen-doped carbon nanotubes (N-CNTs) with hierarchical structure was prepared by sol-gel method without templates or surfactants. Highly conductive and uniformly dispersed N-CNTs incorpated into three dimensional...
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Prospects and challenges of organic/group IV nanomaterial solar cells
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14943E, Feature Article Tao Song, Shuit-Tong Lee, Baoquan Sun
Recent developments of solar cells based on organic (conjugated polymers, small molecules) and group IV (carbon, silicon) nanostructures are reviewed.
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Functional Silk: Colored and Luminescent
AbstractSilkworm silk is among the most widely used natural fibers for textile and biomedical applications due to its extraordinary mechanical properties and superior biocompatibility. A number of physical and chemical processes have also been developed to reconstruct silk into various forms or to artificially produce silk-like materials. In addition to the direct use and the delicate replication of silk's natural structure and properties, there is a growing interest to introduce more new functionalities into silk while maintaining its advantageous intrinsic properties. In this review we assess various methods and their merits to produce functional silk, specifically those with color and luminescence, through post-processing steps as well as biological approaches. There is a highlight on intrinsically colored and luminescent silk produced directly from silkworms for a wide range of applications, and a discussion on the suitable molecular properties for being incorporated effectively into silk while it is being produced in the silk gland. With these understanding, a new generation of silk containing various functional materials (e.g., drugs, antibiotics and stimuli-sensitive dyes) would be produced for novel applications such as cancer therapy with controlled release feature, wound dressing with monitoring/sensing feature, tissue engineering scaffolds with antibacterial, anticoagulant or anti-inflammatory feature, and many others.  Methods to produce colored and luminescent silk through post-dyeing and biological methods are reviewed. In particular, the properties, utility, and versatility of the functional silk are highlighted, as well as the molecular properties-dependent incorporation of various materials into silk while being secreted by silkworms.
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Nanowire Piezo-phototronic Photodetector: Theory and Experimental Design
The piezo-phototronic effect is about the use of the inner crystal piezoelectric potential to tune/control charge carrier generation, separation, transport and/or recombination in optoelectronic devices. In this paper, we have constructed a theoretical model for describing the characteristics of a metal-nanowire-metal structured piezo-phototronic photodetector. Numerical simulations fit well to the experimental results of a CdS and ZnO nanowire based visible and UV detector, respectively.
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Compliant Silver Nanowire-Polymer Composite Electrodes for Bistable Large Strain Actuation
A new compliant electrode-based on silver nanowire-polymercomposite has been developed. The composite electrode has low sheet resistance (as low as 10 Ω/sq), remains conductive (102–103 Ω/sq) at strains as high as 140%, and can support Joule heating. The combination of the composite and a bistable electroactive polymer produces electrically-induced, large-strain actuation and relaxation, reversibly without the need of mechanical programming.
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Two-Photon Continuous Flow Lithography
A new approach for microfluidics-based production of polymeric particles, namely two-photon continuous flow lithography, is reported. This technique takes advantage of two-photon lithography to create objects with sub-micrometer and 3D features, and overcomes the traditional process limitations of two-photon lithography by using multiple beam production under continuous flow. Polymeric fibers, helical and bow-tie particles with sub-diffraction resolution and surface roughness as low as 10 nm are demonstrated.
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Sorting Stable versus Unstable Hypothetical Compounds: The Case of Multi-Functional ABX Half-Heusler Filled Tetrahedral Structures
AbstractElectronic structure theory has recently been used to propose hypothetical compounds in presumed crystal structures, seeking new useful functional materials. In some cases, such hypothetical materials are metastable, albeit with technologically useful long lifetimes. Yet, in other cases, suggested hypothetical compounds may be significantly higher in energy than their lowest-energy crystal structures or competing phases, making their synthesis and eventual device-stability questionable. By way of example, the focus here is on the family of 1:1:1 compounds ABX called “filled tetrahedral structure” (sometimes called Half-Heusler) in the four groups with octet electron count: I-I-VI (e.g., CuAgSe), I-II-V (e.g., AgMgAs), I-III-IV (e.g., LiAlSi), and II-II-IV (e.g., CaZnSn). First-principles thermodynamics is used to sort the lowest-energy structure and the thermodynamic stability of the 488 unreported hypothetical ABX compounds, many of which were previously proposed to be useful technologically. It is found that as many as 235 of the 488 are unstable with respect to decomposition (hence, are unlikely to be viable technologically), whereas other 235 of the unreported compounds are predicted to be thermodynamically stable (hence, potentially interesting new materials). 18 additional materials are too close to determine. The electronic structures of these predicted stable compounds are evaluated, seeking potential new material functionalities.  First-principles thermodynamics is used to determine the lowest-energy structures and stability with respect to decomposition of 488 hypothetical ABX Half-Heusler compounds from the groups I-I-VI, I-II-V, I-III-IV, II-II-IV and it is found that 235 are unstable against decomposition and 18 are too close to determine. 235 other unreported (UR) compounds are predicted to be new stable phases. The electronic structures of these predicted new compounds are evaluated, seeking potential new material functionalities.
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Tin Oxide with Controlled Morphology and Crystallinity by Atomic Layer Deposition onto Graphene Nanosheets for Enhanced Lithium Storage
AbstractAs one of the most promising negative electrode materials in lithium-ion batteries (LIBs), SnO2 experiences intense investigation due to its high specific capacity and energy density, relative to conventional graphite anodes. In this study, for the first time, atomic layer deposition (ALD) is used to deposit SnO2, containing both amorphous and crystalline phases, onto graphene nanosheets (GNS) as anodes for LIBs. The resultant SnO2-graphene nanocomposites exhibit a sandwich structure, and, when cycled against a lithium counter electrode, demonstrate a promising electrochemical performance. It is demonstrated that the introduction of GNS into the nanocomposites is beneficial for the anodes by increasing their electrical conductivity and releasing strain energy: thus, the nanocomposite electrode materials maintain a high electrical conductivity and flexibility. It is found that the amorphous SnO2-GNS is more effective than the crystalline SnO2-GNS in overcoming electrochemical and mechanical degradation; this observation is consistent with the intrinsically isotropic nature of the amorphous SnO2, which can mitigate the large volume changes associated with charge/discharge processes. It is observed that after 150 charge/discharge cycles, 793 mA h g−1 is achieved. Moreover, a higher coulombic efficiency is obtained for the amorphous SnO2-GNS composite anode. This study provides an approach to fabricate novel anode materials and clarifies the influence of SnO2 phases on the electrochemical performance of LIBs.  Both amorphous and crystallineSnO2 are deposited onto graphene nanosheets (GNS) using atomic layer deposition. The amorphous SnO2-GNS is more effective than the crystalline SnO2-GNS in overcoming electrochemical and mechanical degradation due to the intrinsically isotropic nature; it delivers a higher coulombic efficiency, higher energy capacity, and a superior cycling stability.
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Ga2Te3 and Ga3Te2 clusters: understanding their structures, vibrational and energetic features using DFT and ab initio methods
Abstract A study of the Ga2Te3 and Ga3Te2 clusters is presented using three different levels of theory, namely; DFT, MP2 and CCSD(T). We used the 6-311G(d) basis set
for gallium atom and the LANL2DZdp ECP basis set for tellurium atom. The results include geometrical parameters, vibrational
frequencies and energies of the low-lying structures. We report the vertical electron detachment energy (VEDE) and adiabatic
electron detachment energy (AEDE) for the anionic species. The neutral Ga2Te3 cluster adopts a V-shape configuration with 1A1 ground state whilst its anion is kite shaped with 2A1 ground state. On the other hand, the Ga3Te2 and Ga3Te2 ¯ species prefer a three dimensional 6-D3h
geometry with 2A2″ and 1A1′ electronic states, respectively. The adiabatic electron affinity (AEA) for Ga2Te3 is 2.78 eV and that of Ga3Te2 is 2.86 eV at the CCSD(T)//B3LYP level. We analyse, discuss and compare the findings of our research with the analogous gallium
chalcogenides.
- Content Type Journal Article
- Pages 1-10
- DOI 10.1007/s10853-012-6284-7
- Authors
- Neelum Seeburrun, Computational Chemistry Group, Department of Chemistry, University of Mauritius, Réduit, Mauritius
- Melissa M. J. Soopramanien, Computational Chemistry Group, Department of Chemistry, University of Mauritius, Réduit, Mauritius
- Hassan H. Abdallah, School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia
- Edet F. Archibong, Department of Chemistry, University of Namibia, Windhoek, Namibia
- Ponnadurai Ramasami, Computational Chemistry Group, Department of Chemistry, University of Mauritius, Réduit, Mauritius
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Processing and characterization of nanofibrillated cellulose/layered silicate systems
Abstract Recently, nanofibrillated cellulose with cationic functional groups was synthesized. This trimethylammonium-modified nanofibrillated
cellulose (TMA-NFC) was applied in this study for the preparation of composites with various layered silicates. These belonged
to the groups of montmorillonite, kaolin, talc, vermiculite, and mica. The respective composites were prepared by high-shear
homogenization followed by filtration and hot-pressing. Data on crystal structures, chemical compositions, cation exchange
capacity, specific surface area, density, and morphology of all clays and micas themselves as well as structure information
of the corresponding composites have been collected. Possible microstructural features responsible for the composite appearances
were tentatively identified. Principally, the interactions between TMA-NFC and the layered silicates were pronounced, due
to electrostatic attraction of cationic cellulose fibrils and anionic silicate layers. This mutual interaction between TMA-NFC
and layered silicate, however, was influenced not only by layered silicate properties but also by the composite preparation
method, as discussed in this study.
- Content Type Journal Article
- Pages 1-13
- DOI 10.1007/s10853-012-6291-8
- Authors
- T. T. T. Ho, Applied Wood Materials, Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland
- Y. S. Ko, Institute for Polymer, ETH, Swiss Federal Institute of Technology, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland
- T. Zimmermann, Applied Wood Materials, Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland
- T. Geiger, Functional Polymers, Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland
- W. Caseri, Institute for Polymer, ETH, Swiss Federal Institute of Technology, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland
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tert-Butylated spirofluorene derivatives with arylamine groups for highly efficient blue organic light emitting diodes
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14869B, Paper Kum Hee Lee, Seul Ong Kim, Jae Nam You, Sunwoo Kang, Jin Yong Lee, Kyoung Soo Yook, Soon Ok Jeon, Jun Yeob Lee, Seung Soo Yoon
A series of tert-butylated spirofluorene derivatives incorporating a diphenylaminoaryl-vinyl group was synthesized and their photophysical and electroluminescent properties examined. In the case of devices 10A, using 10 as a dopant in the emitting layer, exhibited efficient blue emission with CIE coordinates of (0.15, 0.15).
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Fuel purification, Lewis acid and aerobic oxidation catalysis performed by a microporous Co-BTT (BTT3- = 1,3,5-benzenetristetrazolate) framework having coordinatively unsaturated sites
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15592C, Paper Shyam Biswas, Michael Maes, Amarajothi Dhakshinamoorthy, Mark Feyand, Dirk E. De Vos, Hermenegildo Garcia, Norbert Stock
Performance of a Co-benzenetristetrazolate framework having coordinatively unsaturated sites in fuel purification, Lewis acid and aerobic oxidation catalysis is described.
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Meso-2,3-dimercaptosuccinic acid: from heavy metal chelation to CdS quantum dots
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15741A, Paper Esra Sevinc, F. Sinem Ertas, Gulen Ulusoy, Can Ozen, Havva Yagci Acar
A heavy metal chelating drug, meso-2,3-dimercaptosuccinic acid, was shown to provide a color tunable synthesis of aqueous CdS quantum dots without the need for a separate sulfide source at pH 7.5 and 70 [degree]C.
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Mixed gas adsorption of carbon dioxide and methane on a series of isoreticular microporous metal-organic frameworks based on 2-substituted imidazolate-4-amide-5-imidates
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15811F, Paper Franziska Debatin, Jens Mollmer, Suvendu Sekhar Mondal, Karsten Behrens, Andreas Moller, Reiner Staudt, Arne Thomas, Hans-Jurgen Holdt
IFP-5 based on CoII and 2-methylimidazolate-4-amide-5-imidate has the highest CO2/CH4 selectivity ([small alpha]CO2/CH4 ~7.5) in the series of Imidazolate Frameworks Potsdam.
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Atomic layer deposition of tin oxide with nitric oxide as an oxidant gas
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16557K, Communication Jaeyeong Heo, Sang Bok Kim, Roy G. Gordon
Atomic layer deposition (ALD) of tin oxide (SnO2) thin films was achieved using a cyclic amide of Sn(II) (1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidin-2-ylidene) as a tin precursor and nitric oxide (NO) as an oxidant gas.
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A facile route to carbide-based electrocatalytic nanocomposites
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15558C, Paper Zaoxue Yan, Hui Meng, Pei Kang Shen, Ruihong Wang, Lei Wang, Keying Shi, Honggang Fu
An electrocatalytic nanocomposite prepared by a green route shows high activity for methanol oxidation.
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Synthesis and characterization of cyano-substituted pyridine derivatives for applications as exciton blockers in photovoltaic devices
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15287H, Paper Juanjuan You, Ming-Fai Lo, Weimin Liu, Tsz-Wai Ng, Shiu-Lun Lai, Pengfei Wang, Chun-Sing Lee
By replacing BCP with new EBL materials, the efficiency and half-efficiency lifetime are improved by 44% and 5 times, respectively.
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Near-infrared luminescence of periodic mesoporous organosilicas grafted with lanthanide complexes based on visible-light sensitization
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15158H, Paper Lining Sun, Wenpeng Mai, Song Dang, Yannan Qiu, Wei Deng, Liyi Shi, Wei Yan, Hongjie Zhang
Three new Ln(dbm)3bpd-PMO (Ln = Er, Yb, Nd) materials were synthesized based on the bpd-PMO material as the supporter and Ln(dbm)3(H2O)2 complexes being introduced into the framework of the PMO via a ligand exchange reaction.
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Electrospun fibrous mats as a skeleton for fabricating hierarchically structured materials as sorbents for Cu2+
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM13874C, Paper Yi-nan Wu, Bingru Zhang, Fengting Li, Wei Zhu, Dan Xu, Phillip Hannam, Guangtao Li
This new class of mesoporous silica coated fibrous membranes with the integration of both unique properties of mesoporous materials and electrospun mats provides a useful platform for the development of new functional membrane systems.
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Design and synthesis of plasticizing fillers based on zirconium phosphonates for glycerol-free composite starch films
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15201K, Paper Anna Donnadio, Monica Pica, Marco Taddei, Riccardo Vivani
Novel starch composite films were prepared by using new metal phosphonates which play the double role of reinforcement and plasticizer: flexible films with outstanding thermal and mechanical properties were obtained.
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Solution-processable small molecules as efficient universal bipolar host for blue, green and red phosphorescent inverted OLEDs
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM16463A, Paper Jiangshan Chen, Changsheng Shi, Qiang Fu, Fangchao Zhao, Yue Hu, Yuling Feng, Dongge Ma
Vacuum-evaporable small molecules of SPPO13 and TCTA are employed as a solution-processed bipolar co-host for high efficiency inverted phosphorescent OLEDs.
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Influence of additions of Zr, Ti–B, Sr, and Si as well as of mold temperature on the hot-tearing susceptibility of an experimental Al–2% Cu–1% Si alloy
Abstract This study was undertaken to investigate the effects of chemical composition and mold temperature (MT) on the hot-tearing
susceptibility (HTS) of an experimental Al–2% Cu–1% Si alloy using a constrained rod casting mold. The HTS results were then
compared with 206 (Al–5 wt% Cu) alloys containing the same additions. In general, the Al–2% Cu–1% Si based alloys exhibited
higher resistance to hot-tearing than did the 206-based alloys. It was found that an elevated MT is beneficial in reducing
the HTS of the Al–2% Cu–1% Si and 206 alloys in that the HTS value decreased from over 21 to less than 5, as the MT was increased
from 250 to 450 °C. Increasing the Si content reduced the HTS of the Al–2% Cu–1% Si alloy considerably; this reduction may
be attributed to an increase in the volume fraction of eutectic in the structure. The addition of Sr caused deterioration
in the hot-tearing resistance of the base alloy due to the formation of Sr-oxides and an extension of the freezing range of
the alloy. The refinement of the grain structure obtained with the Zr–Ti–B addition decreased the severity of hot-tearing
as a result of an increase in the number of intergranular liquid films per unit volume and a delay in reaching the coherency
point. It was also observed that α-Fe intermetallic particles may impede the propagation of hot-tearing cracks. The Al–2% Cu–1% Si alloy with 1 wt% Si addition
was judged to be the best composition in view of its low HTS.
- Content Type Journal Article
- Pages 1-13
- DOI 10.1007/s10853-012-6269-6
- Authors
- A. M. Nabawy, Center of Excellence for Research in Engineering Materials, King Saud University, P.O. Box 800, Riyadh, 11421 Saudi Arabia
- A. M. Samuel, Université du Québec à Chicoutimi, Chicoutimi, QC G7H 2B1, Canada
- F. H. Samuel, Center of Excellence for Research in Engineering Materials, King Saud University, P.O. Box 800, Riyadh, 11421 Saudi Arabia
- H. W. Doty, GM Powertrain Group, Metal Casting Technology, Inc, Milford, NH 03055, USA
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Synthesis of multilayered composite nanotube heterostructure; SiC–SiO2, C–SiO2, and C–SiC–SiO2 nanotubes
Abstract Three types of composite nanotube heterostructures (two double-layered and one triple-layered structure) are synthesized by
simple heat treatment, forming SiC–SiO2, C–SiO2, and C–SiC–SiO2 composite coaxial nanotubes. These multilayered composite nanotubes consist of several components with different electrical
properties, for example, metal, semiconductor, and insulator components. In particular, C–SiC–SiO2 triple-layered nanotubes with metallic, semiconducting, and insulating layers are synthesized for the first time. These multilayered
nanotubes can be expected to find applications in nanoscale heterostructure electronic and optical devices.
- Content Type Journal Article
- Pages 1-7
- DOI 10.1007/s10853-012-6290-9
- Authors
- T. Taguchi, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken 319-1195, Japan
- S. Shamoto, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken 319-1195, Japan
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Polymer Microparticles with Controllable Surface Textures Generated through Interfacial Instabilities of Emulsion Droplets
AbstractA general and versatile route to prepare hierarchical polymer microparticles via interfacial instabilities of emulsion droplets is demonstrated. Uniform emulsion droplets containing hydrophobic polymers and n-hexadecanol (HD) are generated through microfluidic devices. When organic solvent diffuses through the aqueous phase and evaporates, shrinking emulsion droplets containing HD and polystyrene (PS) will trigger interfacial instabilities to form microparticles with wrinkled surfaces. Interestingly, surface-textures of the particles can be accurately tailored from smooth to high textures by varying the HD concentration and/or the rate of solvent evaporation. Moreover, composite particles can be generated by suspending different hydrophobic species to the initial polymer solutions. This versatile approach for preparing particles with highly textured surfaces can be extended to other type of hydrophobic polymers which will find potential applications in the fields of drug delivery, tissue engineering, catalysis, coating, and device fabrication.  A facile, yet versatile approach to generate hierarchical polymer microparticles through interfacial instabilities of emulsion droplets is presented. This novel method allows a continuous fine tuning of surface textures and particle morphologies by varying cosurfactant content and/or solvent evaporation rate.
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In Situ Studies of Ion Transport in Microporous Supercapacitor Electrodes at Ultralow Temperatures
AbstractThe ability to quickly store and deliver a significant amount of electrical energy at ultralow temperatures is critical for the energy-efficient operation of high altitude aircraft and spacecraft, exploration of natural resources in polar regions and extreme altitudes, and astronomical observatories exposed to ultralow temperatures. Commercial high-power electrochemical capacitors fail to operate at temperatures below –40 °C. According to conventional wisdom, mesoporous electrochemical capacitor electrodes with pores large enough to accommodate fully solvated ions are needed for sufficiently rapid ion transport at lower temperatures. It is demonstrated that strictly microporous carbon electrodes with much higher volumetric capacitance can be efficiently used at temperatures as low as –70 °C. The critical parameters, with respect to electrolyte properties and electrode porosity and microstructure, needed for achieving both rapid ion transport and efficient ion electroadsorption in porous carbons are discussed. As an example, the fabrication of an electrochemical capacitor with an outstanding performance at temperatures as low as –60 and –70 °C is demonstrated. At such low temperatures the capacitance of the synthesized electrodes is up to 123 F g−1 (≈76 F cm−3), which is 50–100% higher than that of the most common commercial electrochemical capacitor electrode at room temperature. At –60 °C selected cells based on ≈0.2 mm electrodes exhibited characteristic charge–discharge time constants of less than 9 s, which is faster than the majority of commercial devices at room temperature. The achieved combination of high energy and power densities at such ultralow temperatures is unprecedented and extremely promising for the advancement of energy storage systems.  Uniform, microporous, zeolite-templated carbons produced at low pressures demonstrate excellent ion transport and electroadsorption in pores at low temperatures. When used with a carefully designed electrolyte, these properties allow for fabrication of supercapacitors with an unprecedented combination of high specific capacitance, rapid charging ability, and high energy density characteristics at ultralow temperatures.
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Exploring the Origin of the Temperature-Dependent Behavior of PbS Nanocrystal Thin Films and Solar Cells
AbstractTemperature-dependent studies of the electrical and optical properties of cross-linked PbS nanocrystal (NC) solar cells can provide deeper insight into their working mechanisms. It is demonstrated that the overall effect of temperature on the device efficiency originates from the temperature dependence of the open-circuit voltage and the short-circuit current, while the fill factor remains approximately constant. Extensive modeling provides signs of band-like transport in the inhomogeneously coupled NC active layer and shows that the charge transport is dominated by diffusion. Moreover, via low temperature absorption and photoluminescence (PL) measurements, it is shown that the optical properties of PbS thin films before and after benzenedithiol (BDT) treatment exhibit very distinct behavior. After BDT treatment, both the optical density (OD) and PL are shifted to lower energies, indicating the occurrence of electronic wave function overlap between adjacent NCs. Decrease of the temperature leads to additional red-shift of the OD and PL spectra, which is explained by the well-known temperature dependence of the PbS NCs' bandgap. Moreover, BDT treated PbS NCs show unusual properties, such as decrease of the PL signal and broadening of the spectra at low temperatures. These features can be attributed to the partial relaxation of the quantum confinement and the opening of new radiative and nonradiative pathways for recombination at lower temperatures due to the presence of trap states.  Peculiar temperature-dependentelectrical and optical properties of cross-linked PbS nanocrystal thin films are demonstrated. Extensive modeling suggests diffusion-dominated charge transport through the inhomogeneously coupled nanocrystal arrays. After benzenedithiol treatment, the thin films exhibit unusual optical properties that can be attributed to partial relaxation of the quantum confinement and opening of alternative recombination pathways.
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Highly Fluorescent Conjugated Polyelectrolyte Nanostructures: Synthesis, Self-Assembly, and Al3+ Ion Sensing
AbstractA highly fluorescent triazine-bridged polymer, poly[(diphenylamino-s-triazine)-co-(2-methoxy-5-propyloxysulfonate-1,4-phenylene vinylene)] (DTMSPV), is synthesized from Wittig polycondensation of a triazine monomer with a water-soluble p-phenylene vinylene monomer. The fluorescent amphiphilic polymer in aqueous solution self-assembled into nanoassemblies of micelle-like nanostructure (MS) and π stacking nanostructure (πS), which have average sizes of 93 to 270 nm, depending on the concentration of DTMSPV. The micelle-like nanostructure of DTMSPV (MS) shows blue emission at 457 and 488 nm with a high emission quantum yield (ΦE) of 31% in aqueous solution. On the other hand, the ΦE of π stacking structures (πS), formed in a highly concentrated solution, is lower than the MS. The MS exhibits fluorescence quenching as well as color change from blue to green/yellow, depending on the kinds of metal ions. The metal ion sensitivity is larger in the order of the main group ions (Na+, K+) < dicationic transition metal ions (Zn2+, Cd2+, Pb2+, Cu2+, Pd2+) < trivalent transition metal ions (Fe3+, Ru3+), with an exception of Al3+. In particular, the fluorescence of MS is dramatically quenched with color change to yellow in response to Al3+ concentrations. The selectivity and sensitivity of MS to Al3+ are unusually high even in the presence of competitive metal ions, which can be attributed to the specific interaction of triazine units with Al3+.  Highly fluorescent conjugated polyelectrolyte (DTMSPV) with high fluorescence quantum yield is syntheiszed for Al3+ sensing in aqueous solutions. The DTMSPV with dual metal binding sites is self-assembled into stable fluorescent nanostructures in aqueous solution. DTMSPV micelle-like structure (DTMSPV-MS) is sensitive and selective to Al3+, showing a color change from blue to yellow. Al3+ in water is easily eliminated by filtration of precipitates formed by the complexation of the triazine units of the polymer and Al3+.
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Design of an “Active Defense” System as Drug Carriers for Cancer Therapy
AbstractA novel intelligent “active defense” system that can specially respond to cancerous tissues for drug release was designed and prepared. The “active defense” system consists of a biodegradable dextran microgel core cross-linked by a Schiff's base and a surrounding layer formed by Layer-by-Layer (LbL) assembly. The loading and release of macromolecular model drug, dex-FITC, as well as antineoplastic drug, DOX, was investigated. The in vitro cell inhibition and drug release behavior of the drug delivery system were studied and the results showed that the entrapped drug could be explosively released from the microcapsules and thereafter taken up by cancer cells upon the trigger of the acidic environment around tumor tissues.  A novel intelligent “active defense” system that can specially respond to cancerous tissues and explosively release drugs is designed and demonstrated. This “active defense” system consists of a biodegradable dextran microgel core cross-linked by Schiff's base and a surrounding layer formed through layer by layer (LbL) assembly. It is triggered by the tumor environment to act as an exploding microcapsule.
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High-Performance Metal-Free Solar Cells Using Stamp Transfer Printed Vapor Phase Polymerized Poly(3,4-Ethylenedioxythiophene) Top Anodes
AbstractThe use of vapor phase polymerized poly(3,4-ethylenedioxythiophene) (VPP-PEDOT) as a metal-replacement top anode for inverted solar cells is reported. Devices with both i) standard bulk heterojunction blends of poly(3-hexylthiophene) (P3HT) donor and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C60 (PCBM) soluble fullerene acceptor and ii) hybrid inorganic/organic TiO2/P3HT acceptor/donor active layers are studied. Stamp transfer printing methods are used to deposit both the VPP-PEDOT top anode and a work function enhancing PEDOT:polystyrenesulphonate (PEDOT:PSS) interlayer. The metal-free devices perform comparably to conventional devices with an evaporated metal top anode, yielding power conversion efficiencies of 3% for bulk heterojunction blend and 0.6% for organic/inorganic hybrid structures. These encouraging results suggest that stamp transfer printed VPP-PEDOT provides a useful addition to the electrode materials tool-box available for low temperature and non-vacuum solar cell fabrication.  The use of vapor phase polymerized poly(3,4-ethylenedioxythiophene) (VPP-PEDOT) as a metal anode replacement in inverted bulk heterojunction and hybrid organic/inorganic solar cells is reported. The VPP-PEDOT and a work-function enhancing PEDOT:polystyrene sulphonate (PEDOT:PSS) layer are stamp transfer printed on top of the active photogeneration layer. The resulting device performance is equivalent to that for devices made with thermally evaporated Au anodes.
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Engineering Inorganic Nanoemulsions/Nanoliposomes by Fluoride-Silica Chemistry for Efficient Delivery/Co-Delivery of Hydrophobic Agents
AbstractA novel drug-formulation protocol is developed to solve the delivery problem of hydrophobic drug molecules by using inorganic mesoporous silica nanocapsules (IMNCs) as an alternative to traditional organic emulsions and liposomes while preserving the advantages of inorganic materials. The unique structures of IMNCs are engineered by a novel fluoride-silica chemistry based on a structural difference-based selective etching strategy. The prepared IMNCs combine the functions of organic nanoemulsions or nanoliposomes with the properties of inorganic materials. Various spherical nanostructures can be fabricated simply by varying the synthetic parameters. The drug loading amount of a typical highly hydrophobic anticancer drug-camptothecin (CPT) in IMNCs reaches as high as 35.1 wt%. The intracellular release of CPT from carriers is demonstrated in situ. In addition, IMNCs can play the role of organic nanoliposome (multivesicular liposome) in co-encapsulating and co-delivering hydrophobic (CPT) and hydrophilic (doxorubicin, DOX) anticancer drugs simultaneously. The co-delivery of multi-drugs in the same carrier and the intracellular release of the drug combinations enables a drug delivery system with efficient enhanced chemotherapeutic effect for DOX-resistant MCF-7/ADR cancer cells. The special IMNCs-based “inorganic nanoemulsion”, as a proof-of-concept, can also be employed successfully to encapsulate and deliver biocompatible hydrophobic perfluorohexane (PFH) molecules for high intensity focused ultrasound (HIFU) synergistic therapy ex vivo and in vivo. Based on this novel design strategy, a wide range of inorganic material systems with similar “inorganic nanoemulsion or nanoliposome” functions will be developed to satisfy varied clinical requirements.  A simple and efficient drug-formulation protocol is developed to solve the delivery problem of hydrophobic agents. The protocol uses inorganic mesoporous silica nanocapsules as a promising alternative to traditional organic emulsions and liposomes while preserving the advantages of inorganic materials. This is demonstrated by delivery of drugs for cancer chemotherapy and surgery as well as the co-delivery of molecules for enhanced chemotherapy of drug-resistant cancer.
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Digital Microfluidic High-Throughput Printing of Single Metal-Organic Framework Crystals
The first microfluidic method for accurately depositing monodisperse single MOF crystals is presented, enabling unprecedented high-throughput, yet flexible single-crystal printing. Individual droplets of MOF precursor solutions are actuated over a matrix of hydrophilic-in-hydrophobic micropatterns for the controlled generation of femtoliter droplets. As such, thousands of monodisperse single MOF crystals are printed per second in a desired pattern, without the use of impractically expensive equipment.
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Reversible Tuning Luminescent Color and Emission Intensity: A Dipeptide-Based Light-emitting Material
A smartluminescent material whose emission color and emission intensity can be separately modulated by external force is demonstrated. The rational manipulation of rich noncovalent interactions and fluorophore packing style promotes an in-depth understanding between supramolecular structure and photophysical property and offers an effective strategy to modulate the light-emitting property in a predicative way.
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Operational Stability of Organic Field-Effect Transistors
AbstractOrganic field-effect transistors (OFETs) are considered in technological applications for which low cost or mechanical flexibility are crucial factors. The environmental stability of the organic semiconductors used in OFETs has improved to a level that is now sufficient for commercialization. However, serious problems remain with the stability of OFETs under operation. The causes for this have remained elusive for many years. Surface potentiometry together with theoretical modeling provide new insights into the mechanisms limiting the operational stability. These indicate that redox reactions involving water are involved in an exchange of mobile charges in the semiconductor with protons in the gate dielectric. This mechanism elucidates the established key role of water and leads in a natural way to a universal “stress function”, describing the stretched exponential-like time dependence ubiquitously observed. Further study is needed to determine the generality of the mechanism and the role of other mechanisms.  In an organic field-effect transistor redox reactions at the surface of the gate dielectric involving water can lead to conversion of holes in the accumulation layer into protons. The protons diffuse into the gate dielectric and cause a shift of the threshold voltage of the transistor.
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Tuning the Properties of ZnO, Hematite, and Ag Nanoparticles by Adjusting the Surface Charge
A poly (acryl acid) (PAA) post-treatment method is performed to modify the surface charge of ZnO nanospheres, hematite nanocubes, and Ag nanoprisms from highly positive to very negative by adjusting the PAA concentration, to and greatly modify their photoluminescence, cytotoxicity, magnetism, and surface plasmon resonance. This method provides a general way to tune the nanoparticle properties for broad physicochemical and biological applications.
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Controlled Ambipolar Charge Transport Through a Self-Assembled Gold Nanoparticle Monolayer
An active mechanism for controlling ambipolarcharge transport is developed based on self-assembled monolayers of gold nanoparticles. Electron and hole currents are manipulated by controlling the gate bias in order to overcome the intrinsic material limitations. The endurance and retention measurements confirm that this method exhibits good electrical reliability and stability. This solution process approach has potential for applications in large-area printed electronic devices.
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Polarization-Induced Charge Distribution at Homogeneous Zincblende/Wurtzite Heterostructural Junctions in ZnSe Nanobelts
Homogeneous heterostructural wurtzite (WZ)/zincblende (ZB) junctions are successfully fabricated in ZnSe nanobelts. Polarity continuity across the ZB/WZ interface is demonstrated. The saw-tooth-like potential profile induced by spontaneous polarization across the WZ/ZB/WZ interfaces is identified directly at the nanoscale. The polarization-induced charge distribution across the homogeneous heterostructural interfaces is proposed as a viable alternative approach towards charge tailoring in semiconductor nanostructures.
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Spark plasma sintering of a p-type Si1−xGex alloy: identification of the densification mechanism by isothermal and anisothermal methods
Abstract Spark plasma sintering of a p-type Si0.795Ge0.200B0.005 alloy has been investigated in vacuum, in the 400–1200 °C temperature range. The densification mechanism has been determined
using isothermal and anisothermal methods. In spite of a slight material degradation for the highest sintering temperatures
(occurrence of cristobalite nodules homogeneously dispersed in intergranular and intragranular positions), it is proposed
that densification proceeds by grain boundary sliding accommodated most probably by silicon volume diffusion. The microstructure
observation of several sintered samples using transmission electron microscopy supports the densification mechanism advanced.
Because the elemental grains remain mostly equiaxe whatever the sintering conditions, a grain intercalation mechanism may
be also implicated during densification.
- Content Type Journal Article
- Pages 1-13
- DOI 10.1007/s10853-012-6282-9
- Authors
- Guillaume Bernard-Granger, DRT/LITEN/DTNM/LCRE, Commissariat à l’Energie Atomique et aux Energies Alternatives, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
- Amandine Néri, DRT/LITEN/DTNM/LCRE, Commissariat à l’Energie Atomique et aux Energies Alternatives, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
- Christelle Navone, DRT/LITEN/DTNM/LCRE, Commissariat à l’Energie Atomique et aux Energies Alternatives, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
- Mathieu Soulier, DRT/LITEN/DTNM/LCRE, Commissariat à l’Energie Atomique et aux Energies Alternatives, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
- Julia Simon, DRT/LITEN/DTNM/LCRE, Commissariat à l’Energie Atomique et aux Energies Alternatives, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
- Maya Marinova-Atanassova, DRT/LITEN/DEHT/LCPEM, Commissariat à l’Energie Atomique et aux Energies Alternatives, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
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Induced crystallization of rubrene with diazapentacene as the template
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14941A, Paper Danqing Liu, Zhefeng Li, Zikai He, Jianbin Xu, Qian Miao
This study develops a strategy for using diazapentacene as a template to induce crystallization of rubrene in thin film transistors leading to field effect mobility as high as 0.68 cm2 V-1 s-1.
To cite this article before page numbers are assigned, use the DOI form of citation above.
The content of this RSS Feed (c) The Royal Society of Chemistry 
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Chemical doping of EDOT azomethine derivatives: insight into the oxidative and hydrolytic stability
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM14248A, Paper Andreanne Bolduc, Stephane Dufresne, W. G. Skene
Highly coloured EDOT containing azomethines that can be reversibly oxidized electrochemically and chemically in addition to exhibiting a large palette of colours when doped.
To cite this article before page numbers are assigned, use the DOI form of citation above.
The content of this RSS Feed (c) The Royal Society of Chemistry 
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Metal-organic framework-based devices: separation and sensors
J. Mater. Chem., 2012, Advance Article
DOI: 10.1039/C2JM15827B, Applications Bo Liu
Metal-organic framework-based devices and their applications in separation and as sensors are presented.
To cite this article before page numbers are assigned, use the DOI form of citation above.
The content of this RSS Feed (c) The Royal Society of Chemistry 
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Fluorescent Water-soluble Probes Based on Dendritic PEG Substituted Perylene Bisimides: Synthesis, Photophysical properties and Live Cell Image
J. Mater. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2JM30168G, Paper Hongmei Liu, Yongli Wang, Chenghui Liu, hongxia Li, Baoxiang Gao, Licui Zhang, Fuli Bo, Qianqian Bai, Xinwu Ba
Water-soluble dyes based on dendritic polyethylene glycol (PEG)-substituted perylene bisimides were designed and synthesised. According to the distribution of hydrophilic dendritic PEG, these dyes can be divided into two classes:...
The content of this RSS Feed (c) The Royal Society of Chemistry 
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Direct Low-Temperature Integration of Nanocrystalline Diamond with GaN Substrates for Improved Thermal Management of High-Power Electronics
AbstractA novel approach for the direct synthetic diamond–GaN integration via deposition of the high-quality nanocrystalline diamond films directly on GaN substrates at temperatures as low as 450–500 °C is reported. The low deposition temperature allows one to avoid degradation of the GaN quality, which is essential for electronic applications The specially tuned growth conditions resulted in the large crystalline diamond grain size of 100–200 nm without coarsening. Using the transient “hot disk” measurements it is demonstrated that the effective thermal conductivity of the resulting diamond/GaN composite wafers is higher than that of the original GaN substrates at elevated temperatures. The thermal crossover point is reached at ≈95–125 °C depending on the thickness of the deposited films. The developed deposition technique and obtained thermal characterization data can lead to a new method of thermal management of the high power GaN electronic and optoelectronic devices.  A direct method to integrate nanocrystallinediamond (NCD)with gallium nitride (GaN) is demonstrated by tuning growth conditions to form nanocrystalline diamond thin films with grain sizes of 100–200 nm on GaN substrates at low temperature (450
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