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Electroactive polymer Actuators and Devices (EAPAD) 2009

作者： Vargantwar, Pruthesh H. Ghosh, Tushar K. Spontak, Richard J. Departments of Chemical and Biomolecular Engineering Raleigh NC 27695 United States Materials Science and Engineering Raleigh NC 27695 United States Fiber and Polymer Science Program North Carolina State University Raleigh NC 27695 United States

ISBN: (纸本)9780819475473

Nanostructured organic materials derived from block copolymers solvated by block-selective solvents have shown considerable potential as versatile dielectric elastomers. These materials can easily be tuned to achieve the mechanical and electrical properties required for actuator applications. They are lightweight and attractive due to their facile processing, robust properties and reliable performance. Their superb actuation behavior is realized when they are used as dielectric materials under actuation conditions promoting Maxwell compression, which produces large mechanical displacements, coupling efficiencies, and energy densities. These properties generally improve when the material is subjected to mechanical pre-strain. In most cases, mechanical pre-strain is needed to safely achieve application of a desired electrical field. Requisite pre-strain generally necessitates additional overhead in terms of weight and space for the device, and promotes changes in mechanical properties. In this study a new electroactive nanostructured polymer (ENP) is prepared from a triblock copolymer and a nonvolatile block-selective solvent, and evaluated as an actuator candidate. The copolymer exhibits reasonably high actuation strains (up to 70 area%) at relatively low electric fields and energy densities up to 50 kJ/m3 without pre-strain. These performance metrics exceed those reported for conventional dielectric materials such as the VHB acrylic elastomer, as well as those of ENPs derived from styrenic triblock copolymers under no pre-strain. © 2009 SPIE.

关键词： Block copolymers

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Non-volatile memory devices based on polystyrene derivatives with electron-donating oligofluorene pendent moieties

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ACS Applied Materials and Interfaces 2009年第9期1卷 1974-1979页

作者： Liu, Cheng-Liang Hsu, Jung-Ching Chen, Wen-Chang Sugiyama, Kenji Hirao, Akira Department of Chemical Engineering National Taiwan University Taipei 10617 Taiwan Institute of Polymer Science and Engineering National Taiwan University Taipei 10617 Taiwan Department of Organic and Polymeric Materials Tokyo Institute of Technology H-127 2-12-1 Ookayama Meguro-ku Tokyo 152-8552 Japan

We report bistable non-volatile memory devices based on polystyrene derivatives containing pendent electron-donating mono-, di-, and tri(9,9-dihexylfluorene), which are denoted as poly(St-Fl), poly(St-Fl 2), and poly(St-Fl3), respectively. The effects of the oligofluorene chain lengths and polymer surface structures on the memory characteristics were explored. Poly(St-Fl)-, poly(St-Fl2)-, and poly(St-Fl3)-based devices exhibited a flash memory characteristic with different turn-on threshold voltages of 2.8, 2.0, and 1.8 V, respectively, which was on the reverse trend with the highest occupied molecular orbital levels of -5.86, -5.80, and -5.77 eV. Moreover, the memory device showed a high ON/OFF current ratio of 2.5 × 104 and a long retention time of 104 s. The possible mechanism of the switching behavior was explained by the space-charge-limited-current theory and filamentary conduction. The larger aggregation domain size of the polymer thin film processed from the mixed solvent of chlorobenzene/N,N-dimethylformamide probably promoted the diffusion of the Al atoms into the polymer film and formed the conduction channel. Thus, it significantly reduced the turn-on threshold voltage on the studied polymer memory devices. The present study suggested that the polymer memory characteristics could be efficiently tuned through the pendent conjugated chain length and surface structures. © 2009 American chemical Society.

关键词： Threshold voltage

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Antimicrobial activities and cellular responses to natural silicate clays and derivatives modified by cationic alkylamine salts

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ACS Applied Materials and Interfaces 2009年第11期1卷 2556-2564页

作者： Hsu, Shan-Hui Tseng, Hsiang-Jung Hung, Huey-Shan Wang, Ming-Chien Hung, Chiung-Hui Li, Pei-Ru Lin, Jiang-Jen Institute of Polymer Science and Engineering National Taiwan University Taipei 10617 Taiwan Department of Chemical Engineering National Chung Hsing University Taichung 40227 Taiwan Graduate Institute of Basic Medical Science China Medical University Taichung 40402 Taiwan Center of Nanoscience and Nanotechnology National Chung Hsing University Taichung 40227 Taiwan

Nanometer-scale silicate platelet (NSP) materials were previously developed by increasing the interlayer space and exfoliation of layered silicate clays such as montmorillonite and synthetic fluorinated mica by the process of polyamine exfoliation. In this study, the antibacterial activity and cytotoxicity of these nanometer-scale silicate clays were evaluated. The derivatives of NSP (NSP-S) which were modified by C18-fatty amine salts via ionic exchange association exhibited the highest antibacterial activity in the aqueous state among all clays. The high antibacterial activity, however, was accompanied by elevated cytotoxicity. The variations of cell surface markers (CD29 and CD44) and type I collagen expression of fibroblasts treated with the clays were measured to clarify the mechanism of the silicate-induced cytotoxicity. The signal transduction pathway involved the downregulation of extracellular-signal-regulated kinase (ERK), which appeared to participate in silicate-induced cytotoxicity. This study helped to understand the antibacterial potential of NSP and the interaction of natural and modified clays with cellular activities. © 2009 American chemical Society.

关键词： Cell membranes

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Synthesis of acrylic copolymers consisting of multiple amine pendants for dispersing pigment

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Journal of Colloid and Interface science 2009年第1期334卷 42-49页

作者： Chen, Yu-Min Hsu, Ru-Siou Lin, Hsiao-Chu Chang, Shinn-Jen Chen, Shih-Chun Lin, Jiang-Jen Institute of Polymer Science and Engineering National Taiwan University No. 1 Sec. 4 Rosevelt Road Taipei 10617 Taiwan Department of Digital Image Material Material and Chemical Research Laboratories ITRI Hsinchu Taiwan

A class of acrylic copolymers with narrow molecular weight distribution from butyl methacrylate and glycidyl methacrylate comonomers via atom transfer radical polymerization was synthesized. Various types of polarities including hydroxyl-amines, glycols, and carboxylic acids were then grafted onto the oxirane side groups. The resultant comb-like copolymers with different polar pendants were tested for homogenizing a representative Yellow pigment in 1,6-hexanediol diacrylate medium. Specifically, the polyacrylates with 1,3-diamine pendants (7-10 multiplicity on each polymer strain) enabled to homogeneously disperse the pigment than the analogous copolymers with hydroxyl or carboxylic acid groups. Ultimately, the pigment dispersion with an average size of ca. 20 nm in diameter, high transmittance and low viscosity was achieved. Furthermore, the pigment dispersion was allowed to UV-cure into a film, and for the first time, the primary structures of the pigment particles (ca. 50 nm in diameter) were observed by transmission electronic microscope. © 2009 Elsevier Inc. All rights reserved.

关键词： Atom transfer radical polymerization

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Nano/Micro-reological characteristics of polymeric lubricant for hard disk drive

Nano/Micro-reological characteristics of polymeric lubricant...

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Asia-Pacific Magnetic Recording Conference, APMRC 2009

作者： Choi, H.J. Chung, P.S. Guo, Q. Jhon, M.S. Department of Polymer Science and Engineering Inha University Incheon 402-751 Korea Republic of Department of Chemical Engineering and Data Storage Systems Center Carnegie Mellon University Pittsburgh PA 15213 United States

ISBN: (纸本)9789810821913

Rheological properties of shear viscosity and dynamic moduli of perfluoropolyether (PFPE) with different molecular weights and end group functionalities were measured. Molecular simulation of non-equilibrium molecular dynamics (NEMD) was also performed to provide a molecular visualization tool to predict shear viscosity, which reveals a strong dependence on temperature and PFPE molecular architecture.

关键词： Shear viscosity

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Fabrication of multilayer organic solar cells through a stamping technique

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Journal of Materials Chemistry 2009年第24期19卷 4077-4080页

作者： Huang, Jen-Hsien Ho, Zhong-Yo Kuo, Tsung-Hsien Kekuda, Dhananjay Chu, Chih-Wei Ho, Kuo-Chuan Department of Chemical Engineering National Taiwan University Taipei 10617 Taiwan Institute of Polymer Science and Engineering National Taiwan University Taipei 10617 Taiwan Research Center for Applied Sciences Academia Sinica Taipei 11529 Taiwan Department of Photonics National Chao-Tung University Hsinchu 30010 Taiwan

In this article, we demonstrate a simple and reliable stamping technique for fabricating multi-layer solar cells. A poly(di-methylsilane) (PDMS) stamp is used for transferring the active layers onto the substrate. An intermediate solvent treatment is introduced to temporarily modify the PDMS surface;therefore, the polymer film can be uniformly formed on top of the PDMS surface. This method is involves non-contaminative and non-invasive processes, therefore it can avoid possible degradation or contamination of the polymer film and the PDMS stamp can be reused. Devices realized through this stamping technique both by direct and inverted structures exhibited power conversion efficiencies of 3.2 and 2.83% respectively. © 2009 The Royal Society of Chemistry.

关键词： polymer films

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Electrospun Nanofibers from Conjugated Rod-Coil Polyfluorene-block-Poly(2-vinylpyridine)/PEO Blends

Electrospun Nanofibers from Conjugated Rod-Coil Polyfluorene...

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13th Asian chemical Congress

作者： CHIA-HUNG LIN CHI-CHING KUO WEN-CHANG CHEN Department of Chemical Engineering Institute of Polymer Science and Engineering National Taiwan University Department of Chemical Engineering

Morphology and photophysical properties of electrospun(ES)nanofibers prepared from the blends of conjugated rod-coil diblock poly[2,7-(9,9-dihexylfluorene)]-block-Poly(2-vinylpyridine) (PF-b-P2VP)and triblock P2VP-b-PF-b-P2VP copolymers with PEO were *** effects of polymer architecture(diblock ***),polymer composition,and solvent polarity on the fiber

关键词： electrospinning nanofibers rod-coil block copolymer photoluminescence

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New P-type of poly(4-methoxy-triphenylamine)s derived by coupling reactions: Synthesis, electrochromic behaviors, and hole mobility

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Journal of polymer science, Part A: polymer Chemistry 2009年第16期47卷 4037-4050页

作者： Chang, Hui-Wen Lin, Kai-Han Chueh, Chu-Chen Liou, Guey-Sheng Chen, Wen-Chang Institute of Polymer Science and Engineering National Taiwan University 1 Roosevelt Road Taipei 10617 Taiwan Department of Applied Chemistry National Chi Nan University 1 University Road Puli Nantou Hsien 545 Taiwan Department of Chemical Engineering National Taiwan University 1 Roosevelt Road Taipei 10617 Taiwan

Methoxy-substituted poly(triphenylamine)s, poly-4-methoxytriphenylamine (PMOTPA), and poly-N,N-bis(4-methoxyphenyl)-N,N-diphenyl-p- phenylenediamine (PMOPD), were synthesized from, the nickel-catalyzed Yamamoto and oxidative coupling reaction with FeCl3. All synthesized polymers could be well characterized by 1H and 13C NMR spectroscopy. These polymers possess good solubility in common organic solvent, thermal stability with relatively high glass-transition temperatures (TgS) in the range of 152-273 °C, 10% weight-loss temperature in excess of 480 °C, and char yield at 800 °C higher than 79% under a nitrogen atmosphere. They were amorphous and showed bluish green light (430-487 nm) fluorescence with quantum efficiency up to 45-62% in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. All polymers exhibited reversible oxidation redox peaks and Eonset around 0.44-0.69 V versus Ag/AgCl and electrochromic characteristics with a color change under various applied potentials. The series of PMOTPA and PMOPD also showed p-type characteristics, and the estimated hole mobility of O-PMOTPA and Y-PMOPD were up to 1.5 x 10 -4 and 5.6 x 10-5 cm2 V-1 s -1, respectively. The FET results indicate that the molecular weight, annealing temperature, and polymer structure could crucially affect the charge transporting ability. This study suggests that triphenylamine-containing conjugated polymer is a multifunctional material for various optoelectronic device applications. © 2009 Wiley Periodicals, Inc.

关键词： Fluorescence

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Optimization of mechanical performance of oxidative nano-particle electrode nitrile butadiene rubber conducting polymer actuator

Optimization of mechanical performance of oxidative nano-par...

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作者： Kim, Baek-Chul Park, S.J. Cho, M.S. Lee, Y. Nam, J.D. Choi, H.R. Koo, J.C. School of Mechanical Engineering Sungkyunkwan University Suwon 440-746 Korea Republic of Department of Chemical Engineering Sungkyunkwan University Suwon 440-746 Korea Republic of Department of Polymer Science and Engineering Sungkyunkwan University Suwon 440-746 Korea Republic of

Present work delivers a systematical evaluation of actuation efficiency of a nano-particle electrode conducting polymer actuator fabricated based on Nitrile Butadiene Rubber (NBR). Attempts are made for maximizing mechanical functionality of the nano-particle electrode conducting polymer actuator that can be driven in the air. As the conducting polymer polypyrrole of the actuator is to be fabricated through a chemical oxidation polymerization process that may impose certain limitations on both electrical and mechanical functionality of the actuator, a coordinated study for optimization process of the actuator is necessary for maximizing its performance. In this article actuation behav iors of the nano-particle electrode polypyrrole conducting polymer is studied and an optimization process for the mechanical performance maximization is performed © 2009 American Scientific Publishers. All rights reserved.

关键词： Conducting polymers

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Block copolymers with a twist

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Journal of the American chemical Society 2009年第51期131卷 18533-18542页

作者： Ho, Rong-Ming Chiang, Yeo-Wan Chen, Chun-Ku Wang, Hsin-Wei Hasegawa, Hirokazu Akasaka, Satoshi Thomas, Edwin L. Burger, Christian Hsiao, Benjamin S. Department of Chemical Engineering National Tsing Hua University Hsinchu 30013 Taiwan Department of Polymer Chemistry Kyoto University Kyoto 615-8510 Japan Department of Materials Science and Engineering Institute for Soldier Nanotechnologies Massachusetts Institute of Technology Cambridge MA 02139 United States Department of Chemistry Stony Brook University Stony Brook NY 11794-3400 United States

Chiral block copolymers (BCPs*) comprising chiral entities were designed to fabricate helical architectures (i.e., twisted morphologies) from self-assembly. A new helical phase (H*) with P622 symmetry was discovered in the self-assembly of poly(styrene)-b-poly(L-lactide) (PS-PLLA) BCPs*. Hexagonally packed, interdigitated PLLA helical microdomains in a PS matrix were directly visualized by electron tomography. The phase diagram of the PS-PLLA BCPs* was also established. Phase transitions from the H* phase to the stable cylinder and gyroid phases were found after long-time annealing, suggesting that the H* is a long-lived metastable phase. In contrast to racemic poly(styrene)-b-poly(D,L-lactide) BCPs, chiral interaction significantly enhances the incompatibility between achiral PS and chiral PLLA blocks in the PS-PLLA BCPs* and can be estimated through the determination of the interaction parameter. © 2009 American chemical Society.

关键词： Block copolymers

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