bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D Photonic Structures by Sol-Gel Imprint Lithography
Authors: Verschuuren Marc , Sprang Hans Van 
Published: April 2011

ABSTRACTWe present a new and relatively simple process to manufacture three-dimensional sub-micron structures over square centimeter areas using a soft stamp imprinting process. The room-temperature replication process shows excellent quality in transferring features directly into inorganic silica material with pattern distortion smaller than 0.03% over an area of 15×15mm2. Using a self assembly planarization method the imprinting process can be repeated to form three-dimensional structures. As a demonstration, a multilayer stack of four crossed gratings is shown.
Adhesion Promoting Photo-Acid Generator APPAG - A New Class of Lithographic Material
Authors: Sharma Shalini , Sharma Geeta , Meagley Robert 
Published: April 2011

ABSTRACTPhoto-acid generator (PAG) is the key component responsible for the increased sensitivity of chemically amplified resists in use today for microelectronics production. Concentration variation of PAG through the thickness of the photoresist film adversely affects materialís performance. To offset reduced acid concentration at the bottom of the resist, we have developed adhesion promoting photo acid generators, called as a class “APPAG” that enhance acid concentration at interface between the resist and the substrate. An overview on the preparation and characterization of two siloxane based APPAG materials along with a performance comparison of commercial DUV and EUV resists on APPAG is provided. Longer diffusion length photo-acid generator (APPAG 9) retained square profile of critical dimension (CD) at off-focus values and was found to give nearly a 50% improvement in depth of focus for 250nm node DUV lithography. For EUV lithography, both shorter diffusion length APPAG 6 and APPAG 9 were shown to substantially improve performance envelope for 100nm dense lines and spaces at reduced post exposure bake (PEB).
Gas Phase Nanoparticle Integration
Authors: Barry Chad R , Kortshagen Uwe , Jacobs Heiko O 
Published: April 2011

ABSTRACTWe report on two gas phase nanoparticle integration processes to assemble nanomaterials onto desired areas on a substrate. We expect these processes to work with any material that can be charged. The processes offer self-aligned integration and could be applied to any nanomaterial device requiring site specific assembly. The Coulomb force process directs the assembly of nanoparticles onto charged surface areas with sub-100 nm resolution. The charging is accomplished using flexible nanostructured electrodes. Gas phase assembly systems are used to direct and monitor the assembly of nanoparticles onto the charge patterns with a lateral resolution of 50 nm. The second concept makes use of fringing fields. The fringing fields directed the assembly of nanoparticles into openings. The fringing fields can be confined to sub 50 nm sized areas and exceed 1 MV/m, acting as nanolenses. Gas phase assembly systems have been used to deposit silicon, germanium, metallic, and organic nanoparticles.
Reliable Suzuki Chemistry For Functionalised Polythiophene Synthesis
Authors: Higgins Simon , Liversedge Iain , Badriya Samer , Heeney Martin , Giles Mark , McCulloch Iain 
Published: April 2011

AbstractUntil recently, the synthesis of polythiophenes using Suzuki chemistry has proven difficult because of the ready protodeborylation of thiophene boronates. However, we now report that the new generation of bulky, electron-rich Pd(0)-phosphane catalysts are effective and reliable for the preparation of regioregular polyalkylthiophenes using Suzuki coupling. Moreover, the monomers can be prepared in high yield by Ir-catalysed borylation, without the need for strong organolithium bases, making this potentially a highly functional group-tolerant approach to polyalkylthiophene derivatives. Perfluoroalkylthiophenes also undergo this reaction.
Development of A First-Responder Fluorescence Reader for Microarray Cytokine Assay of Human Immune Response to Disease
Authors: Fenner David B. , Rosen David I , Ferrante Anthony A , Stevens Amy E , Bigelow Chad E , Davis Steven J 
Published: April 2011

AbstractDevelopment of field portable apparatus and methods for cytokine assay of human saliva by fluorescent-reporting microarray plates is described. Multiplexed assay of 12 cytokines for minimally-processed saliva is read with a CCD-based imager under LED excitation. Immune responsive cytokines are measured at levels significant for indication of human disease state. The motivational context for the new apparatus development, the general optical design issues, saliva protocol, and image analysis are described.
Bicolor (Red-Yellow) Fluorescence Patterning in Polymer Film Based on Phthalimido Carbamate as a New Group of Photobase Generator
Authors: Chae Kyu Ho , Kim Yoo Ho 
Published: April 2011

AbstractBicolor fluorescent micro-pattern in the polymer film was prepared through the use of a new group of photobase generator containing phthalimido carbamate groups. The photobase generation from phthalimide carbamates was studied from the product analysis of a model compound. The result indicates that amine was produced from the photolytic cleavage of the CN bond of the phthalimide carbamate group. Bicolor fluorescent micropatterns were obtained by treating a copolymer film containing phthalimido groups, which was irradiated with 254 nm UV light through photomask, with fluorescamine and rhodamine, consecutively. Various colored fluorescent micropatterns – green, red, or red-yellow, were obtained on a single polymer film by varying the excitation wavelength.
Some Advances in Liquid Crystal Elastomers: From Crosslinks Affected Ordering to Carbon Nanoparticles Enabled Actuation
Authors: Zumer Slobodan , Chambers Martin , Cordoyiannis George , Finkelmann Heino , Kutnjak Zdravko , Lebar Andrija , Remskar Maja , Zalar Bostjan 
Published: April 2011

AbstractLiquid crystal elastomers (LCE) exhibit a combination of elasticity and mesogenic ordering, yielding large thermally stimulated changes in shape. These LCE systems although well characterised, still yield open questions in the nature of how the crosslinking affects the LCE phase transition. Therefore calorimetry and deuteron-nuclear magnetic resonance were used to study the isotropic-nematic phase transition of uniformly ordered LCE. We observed that the density of crosslinkers strongly affects the nematic-isotropic phase transition. The observed spread critical transitions are explained with a dispersion of local mechanical fields that yields a weakly disordered orientational state composed of regions that exhibit temperature profiles of the nematic order parameter ranging from first order to supercritical. On increasing crosslinking density, the predominantly first order thermodynamic response transforms into a predominantly supercritical one.Additionally, to illustrate the response of these actuating systems, it was demonstrated that a LCE can be electrically heated. The insulating LCE network was reprocessed using conducting nanoparticles dispersed in a solvent with high LCE swelling capability. This results in a low electrical resistivity surface layer of LCE network with a high concentration of conducting nanoparticles. The reprocessing allows the effective resistivity of a LCE film to be reduced from highly insulating values to values useable for electrical actuation. This layer in addition withstands large changes in geometrical shape both in contraction and expansion. Utilizing a resistive “Joule” heating effect, the reprocessed system exhibits an indirect electromechanical effect characterised by a 150% length change that can be cycled for more than 10, 000 times.
Crosslinking High Free Volume Polymers - Effect on Gas Separation Properties
Authors: Shao Lei , Samseth Jon , Hagg May-Britt 
Published: April 2011

AbstractCrosslinkable nanoparticle-filled poly(4-methyl-2-pentyne) [PMP] membranes were cast from carbon tetrachloride solutions containing PMP, hydrophobic fumed silica, and 4,4¡¯-(hexafluoroisopropylidene)diphenyl azide [HFBAA]. The composite membranes were crosslinked by UV irradiation at room temperature. Low levels of the bis azide were effective in rendering the membranes insoluble in cyclohexane and carbon tetrachloride, both good solvents for PMP. The process is simple and effective, and thus PMP can be easily converted to mechanically stable membranes. Compared to the pure PMP membrane, the permeability of the crosslinked membrane is initially reduced for all tested gases due to the crosslinking. By adding nanoparticles, the permeability is again increased, crosslinking is successful in maintaining the permeability and selectivity of PMP over time.
Functionalized Nanoparticles for Composite Polymer Electrolyte
Authors: Toussaint Gilles , Henrist Catherine , Detrembleur Christophe , Jerome Robert , Cloots Rudi 
Published: April 2011

AbstractThe covalent grafting of low-molecular weight poly(ethylene glycol) (PEG) onto high surface silica nanoparticles (Cab-O-Sil EH5) has been accomplished by a multi-step reaction. Reaction involved PEG attachment by epoxide-terminated ring opening of a sylilation agent previously grafted. A maximum grafting density of 0.42 PEG per nm2 has been determined by thermogravimetric analysis (TGA). Differential scanning (DSC) calorimetry confirmed the modification of silica after reaction. Infra-Red (IR) analysis and Carbon-13 Magic Angle Spinning Nuclear Magnetic Resonance (13C MAS NMR) confirmed PEG fixation and opening of the epoxide ring.
Laddersiloxanes: Silsesquioxanes with Defined Ladder Structure
Authors: Unno Masafumi 
Published: April 2011

ABSTRACTA series of structurally-defined laddersiloxanes [1] are presented. Pentacyclic laddersiloxanes were prepared by a stepwise procedure from all-cis-tetraisopropylcyclotetrasiloxanetetraol. All-anti pentacyclic, tetracyclic, tricyclic, and bicyclic laddersiloxanes were obtained by oxidation from respecting all-anti pentacyclic ladder polysilane. Stereocontrolled approach using RS-disiloxanediol as an expanding unit enabled the synthesis of longer laddersiloxanes. Finally, methyl-substituted ladder polysilsesquioxane was obtained by the stepwise transformation from (MePhSiO) 4. The X-ray crystal structures, NMR and IR spectra, and thermal stability of these laddersiloxanes are summarized.
New Generation of Hybrid Organic-Inorganic Macrocellular Foams: Integrative Chemistry Toward Reaching Multifunctional Materials
Authors: Ungureanu Simona , Deleuze Hervé , Birot Marc , Sanchez Clément , Backov Rénal 
Published: April 2011

ABSTRACTThe elaboration of organosilica based hybrid monoliths exhibiting a hierarchically structured bimodal porous structure with tunable functionality have been processed via High Internal Polymeric Emulsion (HIPE) process for the first time. Through one pot synthesis, many organic functionalities that can act as network modifiers (Methyl, Dinitrophenylamino, Benzyl, Mercaptopropyl) or co-network formers (Pyrrol) have been anchored to the amorphous silica porous network. The resulting materials have been thoroughly characterized via a large set of techniques SEM, TEM, SAXS, mercury porosimmetry, nitrogen adsorption isotherms, FTIR, 29Si MAS NMR. These sol-gel derived hierarchical open cell functional hybrid monoliths exhibit macroscopic void spaces ranging from 5 up to 30 [.proportional]m and their accessible micro-mesoporosity, reveal hexagonal organisation for the dinitrophenylamino, benzyl, and pyrrol based hybrids. The average condensation degree for these hybrid networks ranges between 86 and 90% yielding shaped monoliths with both good integrity and sufficient mechanical properties to be usable as functional catalytic or chromatographic supports.
Mesoporous Silica and Titania by Glycol-Modified Precursors
Authors: Geserick Jasmin , Hüsing Nicola , Roßmanith Renate , Weiss Clemens K. , Landfester Katharina , Denkwitz Yvonne , Behm R. Jürgen , Hörmann Ute , Kaiser Ute 
Published: April 2011

ABSTRACTEthylene glycol modified precursors, such as tetrakis(2-hydroxyethyl)orthosilicate (EGMS) or bis(2-hydroxyethyl)titanate (EGMT), have distinct advantages in the synthesis of mesoporous materials by sol-gel processing compared to the commercially available tetraalkoxide precursors. The glycols released upon hydrolysis have proven to be compatible with lyotropic surfactant mesophases and in addition, these precursors allow for processing in purely aqueous conditions. Besides the standard characterization of the resulting titania and silica-based materials by XRD, electron microscopy, and nitrogen sorption, the potential of the titania-based materials for catalytic applications was tested using Au/TiO2 catalysts in low temperature CO oxidation reactions.
Versatile Hybrid Polymers as Matrices for Nanoparticle Preparation
Authors: Feldgitscher Claudia , Ivanovici Sorin , Kickelbick Guido 
Published: April 2011

ABSTRACTHybrid inorganic-organic polymers were prepared applying poly(ethylene oxide) (PEO) crosslinked polysiloxanes as a matrix for the precipitation of metal or metal oxide nanoparticles. Polysiloxanes as flexible and hydrophobic polymer backbones were crosslinked with end-group functionalized PEO by using Pt-catalyzed hydrosilation reactions. Systematic variation of the chain length of the different components resulted in tunable matrices with adjustable hydrophilic regions. The chemical nature of the polysiloxane backbone and the thermal stability of the crosslinked polymer system facilitated nanoparticle preparation through different mechanisms.The crosslinked hybrid polymers were infiltrated with solutions of lanthanide salts, cobalt carbonyl or HAuCl4allowing the application of three different chemical methods (hydrolysis, thermal decomposition, reduction) for nanoparticle preparation. FT-IR, SEM and TEM analyses were used to characterize the insoluble hybrid systems.
Improvements on Flame Retardant Properties of PET/Montmorillonite Nanocomposite Caused by Polyborosiloxane
Authors: Huo Yue , Fan Qinguo , Dembsey Nicholas A , Patra Prabir K 
Published: April 2011

ABSTRACTA phenyl-containing highly cross linked polyborosiloxane (PBSiO) was synthesized as a flame retardant for polyethylene terephthalate (PET). We coated montmorillonite (MMT) clay, a very high aspect ratio and high specific surface area layered silicate with synthesized PBSiO to introduce synergism in flame retardation to the PET nanocomposite film that retained thermal and mechanical properties. This PBSiO has high thermal stability at the processing temperature (270-285° C) of PET and acts as a compatibilizer between PET and clay that are otherwise incompatible. During burning, the flame retardant PET containing PBSiO and MMT forms a protective borosilicatecarbonaceous intumescent char on the surface. Cone calorimeter tests were performed to evaluate key fire properties of the PET/PBSiO/MMT. The peak heat release rate (PHRR) of PET that contains 5 wt% PBSiO and 2.5 wt% MMT was reduced by 60% and similar trend in the reduction of mass loss rate of the nanocomposite was observed.
Hybrid Nanocomposites Based on Metal Oxides and Polysiloxanes with Controlled Morphology
Authors: Ivanovici Sorin , Rill Christoph , Feldgitscher Claudia , Kickelbick Guido 
Published: April 2011

ABSTRACTHybrid materials based on polysiloxanes and metal oxides (SiO2, TiO2, ZrO2) were prepared by hydrosilation of allyl acetoacetate (AAA) modified metal alkoxides (M(OR)4; M = Ti, Zr; R = ethyl, isopropyl) or vinyl triethoxysilane with poly(dimethylsiloxane-co-hydrosiloxane) (PDMS-co-PMHS). The obtained compounds acted as single-source precursors in the sol-gel process. Various spectroscopic methods showed the complete functionalization of the polysiloxane chains with the complexes. When alcohols were used as solvents in the sol-gel process, hybrid nanoparticles were obtained, as observed by dynamic light scattering (DLS) measurements, transmission electron microscopy (TEM), and spectroscopic methods such as NMR and FT-IR.
PECVD Silicon Carbide as a Thin Film Packaging Material for Microfabricated Neural Electrodes
Authors: Hess Allison , Parro Rocco , Du Jiangang , Dunning Jeremy , Scardelletti Maximillian , Zorman Christian A. 
Published: April 2011

AbstractThis paper reports our effort to develop amorphous silicon carbide (a-SiC) films for use as hermetic thin film coatings for mechanically-flexible neural electrodes. In our work, the a-SiC films were deposited by plasma enhanced chemical vapor deposition (PECVD) using two distinct methods, namely a single precursor approach using trimethylsilane, and a dual precursor approach using methane (CH4) and silane (SiH4). The mechanical properties of films deposited on Si substrates were characterized using the wafer curvature and load-deflection methods. The effectiveness of the films as moisture barriers for polyimide substrates was characterized by measuring the leakage currents of SiC-coated interdigitated electrode structures soaked in PBS. A microfabricated prototype of the flat interface nerve electrode (FINE) based on a flexible polyimide substrate and a PECVD SiC capping layer was fabricated using a monolithic process based on conventional micromachining techniques. To facilitate this approach, a reactive ion etching process was developed that exhibited high etch rates and high selectively to the SiC films.
BaZrO3Thin Films For Humidity Gas Sensor
Authors: Chen XiaoXin , Sorenson Michael , Butler Clayton , Rieth Loren , Miller Mark S. , Solzbacher Florian 
Published: April 2011

AbstractMicroscale (MEMS) gas sensing devices for power plant and automobile exhaust gas are being developed. Bulk BaZrO3 has been previously found to be sensitive to H2O at high temperatures, but was never studied in a thin film form. This research thrust focuses on undoped BaZrO3 and doped BaZrO3 with Y.Thin films were deposited on oxidized n-type silicon substrates at room temperature from ceramic targets with an Ar sputtering ambient. Various deposition pressures and deposition powers were used for the initial investigation. The structural and electrical properties of the deposited films were characterized to investigate their relationships to the deposition process parameters. X-ray diffraction (XRD) was used to measure the crystal structure of the deposited films, and in particular was used to determine if any crystallographic texture is present in the films. XRD results indicate the as-deposited films are amorphous before annealing. Films sputtered with and without oxygen in the ambient were compared. The crystal structure and morphology of BaZrO3 and BaZrO3 doped with Y after annealing were also determined. The materials changed from amorphous to crystalline after annealing at temperatures of 800 °C and 1000 °C for 3 hours in forming gas (2% H2 balanced with Ar gas) and oxygen. Temperature was found to dominate over deposition conditions in determining the final film structure. Atomic force microscopy was used to examine the morphology of the thin films. Gas sensor test structures using a Pt thin film metallization for interdigitated electrode structures were fabricated for gas sensing measurements. The experiments with the completed test structures measured the materials¡¦ resistivity as a function of temperature and gas concentration. Both materials decrease in resistance with increasing temperature, which is consistent with ionic conduction. Some experiments tested the gas sensitivity and selectivity of the films to the target gas H2O vapor (humidity) and possible cross sensitive gases H2 and CO2. Both materials need further development to evaluate their suitability for thin film sensors. First, the films were found to be highly resistive, making characterization of the electrical properties very difficult. Second, O2 ambient annealing gas will be applied to compare the crystal structure and morphology of both films with an Ar ambient annealing process.
P3HT:PCBM Bulk Heterojunction Solar Cells: Morphological And Electrical Characterization And Performance Optimization
Authors: Aernouts Tom , Vanlaeke Peter , Haeldermans Ilse , D'Haen Jan , Heremans Paul , Poortmans Jef , Manca Jean V. 
Published: April 2011

AbstractThe performance of organic solar cells based on the blend of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) is strongly influenced by the morphology of the active layer on the nanoscale level. X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) measurements show that ordering of P3HT plays a key role in optimizing the photovoltaic performance. It is demonstrated that the natural tendency of regioregular P3HT to crystallize is disturbed by the addition of PCBM. The crystallinity of the photo-active blend is typically restored by an annealing procedure resulting in improved device performance, characterized by a spectral broadening of the optical absorption.The morphological changes upon annealing of the P3HT:PCBM blends are accompanied by electrical changes as shown in charge carrier mobility measurements. Space-charge limited current measurements have been performed in hole-only devices with various P3HT:PCBM blend ratios. The mobility before and after annealing is compared and from temperature dependent measurements the width of the density of states distribution (DOS) is determined. The hole mobility in pristine P3HT remains practically unaffected by the annealing treatment. The as-produced P3HT:PCBM blends on the other hand, with a more disordered P3HT phase, have a much lower hole mobility. Annealing is capable of increasing the P3HT ordering with as a result an orders of magnitude larger hole mobility, approaching the value found in pristine P3HT. The DOS bandwidths are affected similarly. In the as-produced blend films a value of 100 meV is found, larger than in the annealed films, there reaching a value around 70 meV similar as in pristine P3HT. Variation of the processing solvent demonstrated however that an optimized morphology and charge transport situation can also be obtained without an additional annealing step. It is shown that in that case the as-produced active layer has already a favorable crystalline morphology. We argue that the high boiling point of the solvent plays an important role in this by influencing the evaporation speed during deposition of the photo-active blend. Further proof is delivered that indeed slowing down the evaporation speed can beneficially influence the solar cell performance. Power conversion efficiency over 4% has been achieved in this way.
Simulation and Fabrication of Two Dimensional Nonlinear Photonic Crystals using Barium Titanate Thin Films
Authors: Lin Pao Tai , Liu Zhifu , Wessels Bruce W. 
Published: April 2011

AbstractPhotonic crystal (PhC) can potentially result in enhanced optical properties around critical points in the photonic band gap. Of interest here are enhanced nonlinear optical effects. In this study, one and two dimensional nonlinear PhC were designed and fabricated using barium titanium oxide (BTO) thin films as the active medium. Nonlinear PhC made with barium titanate thin films potentially provide integrated devices with the advantages of wide tunability and high stability. Films 500 nm thick deposited on MgO substrates were utilized. Two dimensional PhC structures were defined by focused ion beams (FIB). Before patterning, a thin metal layer was deposited on the barium titanate layers in order to improve the conductivity of the samples. After writing the patterns, cylindrical air holes were generated in the thin film layers. The PhC lattice constant and the hole radius were selected in sub-micron region in order to satisfy the requirement of wave resonance. The PhCs with sub-micron features were characterized by the atomic force microscopy (AFM), scanning electron microscopy (SEM), and near field optical microscopy (NSOM). The transmission spectra of the PhC waveguides were calculated with a continuous wide band source that covered 1 to 2 micron wavelength. Simulations of the transmission characteristics were performed using the two dimensional finite difference time domain method (FDTD).