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Crosslinking of chitosan fibers with dialdehydes: Proposal of a new reaction mechanism

Journal of Polymer science 1999年第11期37卷

作者： Jonathan Z. Knaul Samuel M. Hudson Katherine A. M. Creber Department of Chemistry and Chemical Engineering Royal Military College PO Box 17000 Station Forces Kingston Ontario K7K 7B4 Canada Fiber and Polymer Science Program Box 8301 Centennial Campus North Carolina State University Raleigh North Carolina 27695-8301

A highly deacetylated chitosan from shrimp with a degree of deacetylation of 95.28 ± 3.03% was prepared and spun into a monofilament fiber using a solution of 4% (w/v) chitosan in 4% (v/v) aqueous acetic acid. Samples of the spun fibers were immersed in aqueous solutions containing glutaraldehyde and glyoxal, and subsequently washed and dried. When the concentration of crosslinking agent was varied at room temperature over a constant time of 1 h, dry mechanical properties improved up to a point after which increasing concentrations resulted in degradation. Immersion time was also varied between 1 and 60 min at 25.8°C, and temperature was varied between 25.8 and 70.0°C, at fixed concentrations of both glyoxal and glutaraldehyde. It was demonstrated that mechanical improvements might be rendered at higher temperatures over lesser times. However, it was also shown that at higher temperatures, fiber mechanical properties would begin to diminish. Chitosan films were subjected to similar treatments in aqueous crosslinking solutions. Fourier transform infrared data (FTIR) on the films suggest that some interaction is occurring between the glutaraldehyde or glyoxal and the amine group on the chitosan backbone. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1079–1094, 1999

关键词： chitosan fiber crosslinking mechanical films FTIR wet spinning

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Contributory presentations/posters

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Journal of Biosciences 1999年第1期24卷 33-198页

作者： N. Manoj V. R. Srinivas A. Surolia M. Vijayan K. Suguna R. Ravishankar R. Schwarzenbacher K. Zeth Diederichs G. M. Kostner A. Gries P. Laggner R. Prassl Madhusudan Pearl Akamine Nguyen-huu Xuong Susan S. Taylor M. Bidva Sagar K. Saikrishnan S. Roy K. Purnapatre P. Handa U. Varshney B. K. Biswal N. Sukumar J. K. Mohana Rao A. Johnson Vasantha Pattabhi S. Sri Krishna Mira Sastri H. S. Savithri M. R. N. Murthy Bindu Pillai Kannan M. V. Hosur Mukesh Kumar Swati Patwardhan K. K. Kannan B. Padmanabhaa S. Sasaki-Sugio M. Nukaga T. Matsuzaki S. Karthikevan S. Sharma A. K. Sharma M. Paramasivam P. Kumar J. A. Khan S. Yadav A. Srinivasan T. P. Singh S. Gourinath Neelima Alam A. Srintvasan Vikas Chandra Punit Kaur Ch. Betzel S. Ghosh A. K. Bera S. Bhattacharya S. Chakraborty A. K. Pal B. P. Mukhopadhyay I. Dey U. Haldar Asok Baneriee Jozef Sevcik Adriana Solovicova K. Sekar M. Sundaralingam N. Genov Dong-cai Liang Tao Jiang Ji-ping Zhang Wen-rui Chang Wolfgang Jahnke Marcel Blommers S. C. Panchal R. V. Hosur Bindu Pillay Puniti Mathur S. Srivatsun Ratan Mani Joshi N. R. Jaganathan V. S. Chauhan H. S. Atreya S. C. Sahu K. V. R. Chary Girjesh Govil Elisabeth Adjadj Éric Quinjou Nadia Izadi-Pruneyre Yves Blouquit Joël Mispelter Bernadette Heyd Guilhem Lerat Philippe Milnard Michel Desmadreil Y. Lin B. D. Nageswara Rao Vidva Raghunathan Mei H. Chau Prashant Pesais Sudha Srivastava Evans Coutinho Anil Saran Leizl F. Sapico Jayson Gesme Herbert Lijima Raymond Paxton Thamarapu Srikrishnan C. R. Grace G. Nagenagowda A. M. Lynn Sudha M. Cowsik Sarata C. Sahu S. Chauhan A. Bhattacharya G. Govil Anil Kumar Maurizio Pellecchia Erik R. P. Zuiderweg Keiichi Kawano Tomoyasu Aizawa Naoki Fujitani Yoichi Hayakawa Atsushi Ohnishi Tadayasu Ohkubo Yasuhiro Kumaki Kunio Hikichi Katsutoshi Nitta V. Rani Parvathy R. M. Kini Takumi Koshiba Yoshihiro Kobashigawa Min Yao Makoto Demura Astushi Nakagawa Isao Tanaka Kunihiro Kuwajima Jens Linge Seán O. Donoghue Michael Nilges G. Chakshusmathi Girish S. Ratnaparkhi P. K. Madhu R. Varadarajan C. Tetreau Molecular Biophysics Unit Indian Institute of Science Bangalore India Austrian Academy of Sciences Institute of Biophysics and X-ray Structure Research Graz Austria Faculty of Biology University of Konstanz Germany Institute of Medical Biochemistry University of Graz Austria Howard Huges Medical Institute Department of Chemistry & Biochemistry University of California La Jolla USA Department of Chemistry & Biochemistry University of California San Diego La Jolla USA Molecular Biophysics Unit India Department of Microbiology &Cell Biology Indian Institute of Science Bangalore India Macromolecular Structure Laboratory NCI - Frederick Cancer Research and Development Center ABL - Basic Research Program Frederick USA Department of Crystallography and Biophysics University of Madras Chennai Biochemistry Department Indian Institute of Science Bangalore India Condensed Matter Physics Division B.A.R.C. Trombay Mumbai Condensed Matter Physics Division Bhabha Atomic Research Centre Trombay Mumbai IMCB The University of Tokyo Tokyo Japan Mitsubishi Chemical Corporation Yokohama Research Center Yokohama Japan Faculty of Pharmaceutical Sciences Chiba University Chiba Japan Department of Biophysics All India Institute of Medical Sciences New Delhi India Department of Biophysics All India Institute of Medical sciences New Delhi India Institüt Physiologische Chemie Hamburg Germany Biophysics Department Bose Institute Calcutta India Slovak Academy of Sciences Institute of Molecular Biology Bratislava Slovakia Indian Institute of Science Bioinformatics Centre Bangalore Departments of Chemistry and Biochemistry Biological Macromolecular Structure Center USA Bulgarian Academy of Sciences Institute of Organic Chemistry Sofia Bulgaria Chinese Academy of Sciences Institute of Biophysics Beijing China Novartis Pharma AG Preclinical Research Basel Switzerland Department of Chemical Sciences Tata Institute of Fundamental Research Mumbai India Solid State Physics Div

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Observation and analysis of the infiltration of polymer liquids into carbon black agglomerates

Observation and analysis of the infiltration of polymer liqu...

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作者： Yamada, H. Manas-Zloczower, I. Feke, D.L. Department of Macromolecular Science Case Western Reserve University Cleveland OH 44106 United States Department of Chemical Engineering Case Western Reserve University Cleveland OH 44106 United States

The infiltration of polymeric liquids into carbon black agglomerates has been studied using buoyancy measurements. Both the rate of infiltration and the degree of saturation decrease with increasing matrix viscosity. The influence of interfacial chemistry was demonstrated by comparing the enhanced infiltration and saturation that occurs with polybutadiene and ethylene propylene copolymers in comparison to polydimethyl siloxane liquids. However, the differences attributable to interfacial chemistry are masked when highly viscous liquids are used. The influence of the agglomerate pore structure on infiltration and saturation characteristics was also examined. In the case of low-structure carbon black, the infiltration and saturation characteristics showed a sensitivity to packing density while the same was not true for agglomerates of the high structure carbon black.

关键词： Carbon black

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Spinodal Dewetting of Thin Polymer Films

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Physical Review Letters 1998年第6期81卷 1251-1251页

作者： R. Xie A. Karim J. F. Douglas C. C. Han R. A. Weiss Polymer Science Program and Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269 Polymers Division National Institute of Standards and Technology Gaithersburg Maryland 20899

Dewetting of polystyrene films on a silicon substrate is investigated as a function of film thickness h. We observe the nucleation of holes in the early stage of dewetting for relatively thick films (h>100Å), as observed previously, but the breakup of thinner films occurs through the growth of uniformly distributed surface undulations (“spinodal dewetting”). The average amplitude δh of these undulations increases exponentially up to the film rupture point where δh becomes comparable to h, as predicted by a capillary wave instability model.

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Nonlinear theology and flow-induced structure in a concentrated spherical silica suspension

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Rheologica Acta 1998年第1期37卷 1-6页

作者： Watanabe, Hiroshi Yao, Ming-Long Osaki, Kunihiro Shikata, Toshiyuki Niwa, Hirokazu Morishima, Yotaro Balsara, Nitash P. Wang, Hao Institute for Chemical Research Kyoto University Uji Kyoto-fu 611 Japan Rheometric Scientific F.E. 2-19-6 Yanagibashi Taito-ku Tokyo 111 Japan Department of Macromolecular Science Osaka University Toyonaka Osaka 560 Japan Department of Chemical Engineering Polytechnic University Six Metrotech Center Brooklyn NY 11201 United States

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MULTIPLE STATES OF A VISCOUS FREE SURFACE FLOW: TRANSITION FROM PRE-METERED TO A METERING INFLOW

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International Journal for Numerical Methods in Fluids 1998年第9期24卷

作者： M. S. Carvalho L. E. Scriven Coating Process Fundamentals Program Center for Interfacial Engineering and Department of Chemical Engineering and Material Science University of Minnesota Minneapolis MN 55455 U.S.A.

In a forward-roll coating gap or nip, steady laminar flow of liquid between counter-rotating cylinders or rolls is used to split the flow into a coated layer on one roll and a rejected layer on the other. Both layers have free surfaces in contact with air. Liquid may be carried into the gap as a layer on one or both rolls. If the arriving layer is not too thick, all of the liquid flows through the gap, a situation called pre-metered . If the arriving layer is too thick, part of the liquid is rejected and runs back down the lower roll. The flow rate through the gap is said to be metered and is not known a priori . The transition from a pre-metered regime to the metered situation was examined by solving the Navier–Stokes system for steady, two-dimensional flow in a domain bounded by free surfaces, two rigid roll surfaces and chosen inflow and outflow surfaces. The free boundary condition , as described by Papanastasiou et al. ( Int. j. numer methods fluids , 14 , 587 (1992)), was explored and proved to accommodate both the pre-metered and metered regimes. A run-back flow state across the synthetic inlet plane was obtained, provided a condition on the thickness of the arriving layer was replaced by a kinematic condition at a certain stage. The coupled equation system was solved by Galerkin's method with finite element basis functions. The resulting non-linear algebraic system was solved by Newton's method with initialization by pseduo-arc-length continuation and automatic parameter step adjustment. Results show the existence of multiple solutions which can lead to hysteresis. Flow regime maps were constructed to portray the operating parameter range in which a coating bead can exist and the ranges in which a coating gap operates in either the pre-metered or the metering regime. © 1997 by John Wiley & Sons, Ltd. Int. j. numer. methods fluids 24: 813–831, 1997.

关键词： pre-metered metered free boundary condition free surface flow viscous

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In vitroandin vivodegradation of poly(propylene fumarate-co-ethylene glycol) hydrogels

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Journal of Biomedical Materials Research Part B: Applied Biomaterials 1998年第2期42卷

作者： Laura J. Suggs Ravi S. Krishnan C. Alejandra Garcia Susan J. Peter James M. Anderson Antonios G. Mikos Cox Laboratory for Biomedical Engineering Institute of Biosciences and Bioengineering and Department of Chemical Engineering Rice University 6100 South Main Street Houston Texas 77251-1892 Departments of Pathology Biomedical Engineering and Macromolecular Science Case Western Reserve University Cleveland Ohio 44106

The degradation of poly(propylene fumarate-co-ethylene glycol) hydrogels was examined in vitro in phosphate-buffered saline at pH 7.4 and in vivo in a subcutaneous rat model. These hydrogels have potential application as biodegradable, injectable cardiovascular stents, and, as such, their mass loss, dimensional changes, mechanical properties, morphology, and biocompatiblity over a 12-week time course were evaluated. Three formulations were fabricated: one base formulation consisting of 25% (w/w) PEG, molecular weight 4,600; one high weight percent PEG formulation with 50% (w/w) PEG; and one high molecular weight PEG formulation, molecular weight 10,500. All three formulations showed significant weight loss (between 40 and 60%) on the first day due to leaching of the uncrosslinked fraction. Further weight loss was observed only for the low weight percent PEG copolymers in the in vivo case, and a slight increase in volume was observed due to degradative swelling. The mechanical properties of the P(PF-co-EG) hydrogels decreased significantly in the first 3 weeks, showing the biphasic pattern typical of bulk degradation. In vitro , the hydrogels showed at least a 20% retention of their initial ultimate tensile stress after 3 weeks. The dynamic mechanical properties showed similar retention, with the in vivo mechanical properties differing from the in vitro properties only after 6 weeks of degradation. Differences in PEG molecular weight appeared to have little effect, but increasing the weight percent PEG decreased the rate of degradation both in vitro and in vivo . The morphology of the copolymer films, based on scanning electron microscopy observation, was not significantly different either among the three formulations or over the time course of the study, suggesting there were no macroscopic structural changes during this time period. The P(PF-co-EG) hydrogels demonstrated good initial biocompatibility, showing responses characteristic of biomaterial implants. © 1998

关键词： cardiovascular stents hydrogels poly(ethylene glycol) poly(propylene fumarate) biodegradation tissue engineered implants

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Multicomponent latex IPN materials: 2. Damping and mechanical behavior

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Journal of Polymer science 1998年第10期35卷

作者： R. Hu V. L. Dimonie M. S. El-Aasser R. A. Pearson A. Hiltner S. G. Mylonakis L. H. Sperling Emulsion Polymers Institute Department of Chemical Engineering Department of Chemistry Polymer Interfaces Center Department of Materials Science and Engineering Center for Polymer Science and Engineering Materials Research Center Lehigh University Bethlehem Pennsylvania 18015-3194 Department of Macromolecular Science and Center for Applied Polymer Research Case Western Reserve University Cleveland Ohio 44106 7009 Cashell Manor Court Derwood Maryland 20855

The integrals of the linear loss shear modulus vs. temperature (loss area, LA) and linear tan δ vs. temperature (tan δ area, TA) were characterized for various core/shell latex particles with synthetic rubber, poly(butadiene- stat -styrene) [P (Bd/S), 90/10], and interpenetrating polymer networks (IPN) as the cores. The IPN cores were composed of P(Bd/S) ( T g ≃ − 70°C) and an acrylate based copolymer ( T g around 10°C) for potential impact and damping improvement in thermoplastics. Poly(styrene- stat -acrylonitrile) (SAN, 72/28) was the shell polymer for all these polymers. Under the same loading, for both toughening and damping controls, among the IPN core/shell, blend of separate core/shell, and multilayered core/shell polymers, the IPN core/shell polymers were the best dampers. However, the other core/shell polymers also showed higher LA values than P(Bd/S)/SAN core/shell polymer. A comparison of LA values via a group contribution analysis method was made, the effect of particle morphology and phase continuity on damping being studied. Inverted core/shell latex particles (glassy polymer SAN was synthesized first) showed much higher LA and TA values than normal core/shell ones (rubbery polymer was synthesized first). Models for maximum LA and TA behavior are proposed. The damping property was essentially controlled by the phase miscibility and morphology of the core/shell latex particles. The LA values for each peak in these multiphase materials provided some indication of the several fractional phase volumes. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1501–1514, 1997

关键词： multicomponent latex interpenetrating polymer networks IPN core/shell damping loss area

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The development of conductive composite surfaces by a diffusion-limitedin situpolymerization of pyrrole in sulfonated polystyrene ionomers

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Journal of Polymer science 1998年第2期35卷

作者： M. Cristina De Jesus R. A. Weiss Yuping Chen Polymer Science Program and Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269-3136 State Key Laboratory of Engineering Plastics Institute of Chemistry Academia Sinica Beijing 10080 China

Electrically conductive composite surfaces were prepared by a diffusion-controlled in situ polymerization of pyrrole in the surface layer of sulfonated polystyrene ionomer films. Premolded films of the ionomer sulfonic acid derivatives were sequentially immersed in aqueous solutions of pyrrole and FeCl 3 , and polymerization occurred only where both the monomer and the oxidant were present. The penetration of the polypyrrole (PPy) into the film was controlled by varying the immersion time in the monomer solution. The amount of PPy produced depended on the immersion time of the film in the monomer and the degree of sulfonation of the ionomer. Surface conductivities of 10 −4 -10 −1 S/cm were achieved with PPy concentrations from 2 to 22 wt % and composite layers as thin as 15 μm. Intermolecular interactions occurred between PPy and the ionomer by proton transfer. Incorporation of PPy also increased the tensile strength of the ionomer film, significantly increased its modulus above T g , and inhibited melt flow. © 1997 John Wiley & Sons, Inc.

关键词： polypyrrole electrical conductivity composite surfaces

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Electrical properties of block copolymers containing silver nanoclusters within oriented lamellar microdomains

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Journal of Applied Polymer science 1998年第4期65卷

作者： B. H. Sohn R. E. Cohen Program in Polymer Science and Technology Massachusetts Institute of Technology Cambridge Massachusetts 02139 Department of Chemical Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139

Films containing silver nanoclusters within a lamellar morphology were obtained via postprocessing reduction of the silver‐containing regions of block copolymers synthesized by ring opening metathesis polymerization. Solution‐cast films (0.1 mm thickness) of the block copolymer exhibited an oriented lamellar morphology with lamellar normals perpendicular to the film plane. The slightly anisotropic dielectric properties, perpendicular and parallel to the film plane, were investigated by direct measurement and by model calculations. The conductivity was highly anisotropic, differing by at least four orders of magnitude in directions parallel and perpendicular to the film plane. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 723–729, 1997

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