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Amino acid-based bioanalogous polymers. Synthesis, and study of regular poly(ester amide)s based on bis(α-amino acid) α,ω-alkylene diesters, and aliphatic dicarboxylic acids

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Journal of polymer science 2000年第4期37卷

作者： R. Katsarava V. Beridze N. Arabuli D. Kharadze C. C. Chu C. Y. Won Centre for Medical Polymers and Biomaterials of Ministry of Health and Institute of Molecular Biology & Biophysics of Georgian Academy of Sciences P.O. Box 24 380079 Tbilisi-79 Georgia Fiber and Polymer Science Program Department of Textiles & Apparel & Biomedical Engineering Program Cornell University Ithaca New York 14853-4401

The purpose of this research was to synthesize new regular poly(ester amide)s (PEAs) consisting of nontoxic building blocks like hydrophobic α-amino acids, α,ω-diols, and aliphatic dicarboxylic acids, and to examine the effects of the structure of these building block components on some physico-chemical and biochemical properties of the polymers. PEAs were prepared by solution polycondensation of di- p -toluenesulfonic acid salts of bis-(α-amino acid) α,ω-alkylene diesters and di- p -nitrophenyl esters of diacids. Optimal conditions of this reaction have been studied. High molecular weight PEAs ( M w = 24,000–167,000) with narrow polydispersity ( M w / M n = 1.20–1.81) were prepared under the optimal reaction conditions and exhibited excellent film-forming properties. PEAs obtained are mostly amorphous materials with T g from 11 to 59°C. α-Chymotrypsin catalyzed in vitro hydrolysis of these new PEA substrates was studied to assess the effect of the building blocks of these new polymers on their biodegradation properties. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 391–407, 1999

关键词： α-amino acids biodegradable polymers regular poly(ester amide)s α-chymotrypsinolysis

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Synthesis and characterization of dextran-maleic acid based hydrogel

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Journal of Biomedical Materials Research Part B: Applied Biomaterials 1999年第2期46卷

作者： Sin-Hee Kim Chee-Youb Won Chih-Chang Chu Fiber and Polymer Science Program Department of Textiles & Apparel and Biomedical Engineering Program Cornell University Ithaca New York 14853-4401

A new class of hydrogel precursor, dextran-maleic acid (Dex-MA), was synthesized by the reaction of dextran with maleic anhydride in the presence of the catalyst triethylamine. The effects of temperature, time, catalyst amount, and reactant concentration on the degree of substitution (DS) by MA was studied to establish an optimum reaction condition. The new hydrogel precursor had excellent solubility in various common organic solvents. The hydrogels based on Dex-MA precursor were made by the irradiation of Dex-MA with a long wave UV lamp. The Dex-MA hydrogels showed a very high swelling ratio in water, and the magnitude of swelling depended on the pH of the medium and the DS by MA. The Dex-MA hydrogels exhibited the highest swelling ratio in neutral pH, followed by acidic (pH 3) and alkaline pH (10). The most distinctive characteristic of Dex-MA hydrogels was that a carboxylic acid group was generated by the reaction of dextran with maleic anhydride. As a result, the swelling ratio increased with an increase of the DS of the MA segment (ionizable moiety that affects swelling ratio) in the Dex-MA hydrogel. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 46, 160–170, 1999.

关键词： dextran maleic anhydride photocrosslinked hydrogel swelling hydrolytic degradation

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

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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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Segmented block copolyetheramides based on nylon 6 and polyoxypropylene. III. SAXS analysis

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Journal of Applied polymer science 1998年第11期64卷

作者： Yeong Chool Yu Won Ho Jo Moo Sung Lee Department of Fiber and Polymer Science Seoul National University Seoul 151‐742 Korea Department of Textile Engineering Chonnam National University Kwangju 500‐757 Korea

Morphologic characteristics of segmented block copolyetheramides based on nylon 6 and polyoxypropylene (POP) were investigated as a function of the compositions and block lengths of the hard and soft segments using small angle X‐ray scattering (SAXS). Three POPs with different molecular weights were used as a soft segment. One‐dimensional correlation functions were obtained from the desmeared intensity SAXS curves using the method developed by Vonk and Kortleve. The interdomain spacings were determined from the correlation distance at the peak position of the correlation function. From the dependence of the correlation distance on soft segment content, we deduced that an increase in the hard‐segment length may lead to crystal formation by a chain‐folding mechanism. The thickness of phase boundary was determined from the smeared intensity data using the method of Koberstein. A decrease in the phase boundary thickness with increasing soft‐segment content suggests that an increase in the chain mobility by soft segment facilitates the regular arrangement of the hard segment, resulting in the formation of the hard domain with a narrow interfacial region. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2155–2163, 1997

关键词： copolyesteramides SAXS interfacial thickness morphology

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Preparation of poly(ethylene terephthalate-co-isophthalate) by ester interchange reaction in the PET/PEI blend system

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Journal of polymer science 1998年第2期35卷

作者： Wan Shik Ha Yong Kun Chun Seung Soon Jang Do Mook Rhee Chong Rae Park Department of Fiber and Polymer Science College of Engineering Seoul National University Seoul 151-742 Korea Textile Research Department Sam Yang Group R&D Center Taejeon Korea Department of Textile Engineering College of Engineering Sung Kyun Kwan University Suwon 440-746 Korea

Optimum conditions for the synthesis of PEI of considerable molecular weight have been established. Poly(ethylene terephthalate- co -isophthalate) (PETI) has been prepared through the ester interchange reaction of a blend of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI). NMR analysis has indicated that the PETI changes from a block-type copolymer to a random type copolymer as the ester interchange reaction proceeds. If the reaction is limited to 20 min, the resulting PETI is crystallizable. The effects of catalysts that have been used during the synthesis of PEI on the characteristics of PETI are also discussed. © 1997 John Wiley & Sons, Inc.

关键词： PETI ester interchange reaction PET/PEI melt blend sequence randomness

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Effect of interchange reactions on the molecular weight distribution of poly(ethylene terephthalate): A Monte Carlo simulation

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Journal of polymer science 1996年第4期34卷

作者： Won Ho Jo Jae Woo Lee Moo Sung Lee Chung Yup Kim Department of Fiber and Polymer Science Seoul National University Seoul 151-742 Korea Department of Textile Engineering Chonnam National University Kwangju 500-757 Korea Polymer Materials Laboratory Korea Institute of Science and Technology Seoul 130-650 Korea

The effect of the interchange reactions of poly(ethylene terephthalate) (PET) on its molecular weight distribution (MWD) was analyzed using a Monte Carlo simulation method. Three kinds of motions, which correspond to the direct ester(SINGLEBOND)ester interchange reaction, alcoholysis, and internal alcoholysis in polyester, were performed in this simulation: bond flip, end attack, and backbite. Two systems with two different types of nonequilibrium distribution (monodisperse and bimodal distribution) were initially prepared. The initial biases from equilibrium MWD are rapidly relaxed to an equilibrium MWD as the reaction progresses. The MWD at equilibrium is well described by the most probable MWD proposed by Flory. From the polydispersity data, it is concluded that about 0.3 interchanges per segment are sufficient to equilibrate the nonequilibrium system. For the validity of the simulation, the variation of MWD of the mixtures of two PETs having different molecular weights were monitored using gel permeation chromatography. The agreement between simulation and experiment is remarkably good. © 1996 John Wiley & Sons, Inc.

关键词： poly(ethylene terephthalate) ester interchange reaction Monte Carlo simulation molecular weight distribution gel permeation chromatography

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Oriented noncrystalline structure in PET fibers prepared with threadline modification process

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Journal of polymer science 1996年第12期34卷

作者： Gang Wu Jiao-Dong Jiang Paul A. Tucker John A. Cuculo Department of Polymer Science Beijing University of Chemical Technology Beijing 100029 China Department of Fibrous Material Engineering Beijing Institute of Clothing Technology Beijing 100029 China Fiber & Polymer Science Program College of Textiles North Carolina State University Raleigh North Carolina 27695

The development of an oriented noncrystalline phase in a semicrystalline polymer filament has been studied via X-ray scattering. These unique PET fibers contain a relatively high noncrystalline content and also have high tenacity, high modulus, and low breaking elongation. fiber properties were found to be very responsive to the oriented amorphous phase content. This phase was utilized for interpreting noncrystalline orientation in PET fibers produced by a new extrusion technique. Here, the oriented noncrystalline regions in a series of PET fibers varies from 6% to 63%, depending strongly on the production conditions. In particular, samples produced with a newly developed threadline modification process possess a high content of oriented noncrystalline polymer. Measurements such as dynamic and static mechanical properties have been performed on various samples, and these properties are related to the oriented noncrystalline phase. The results provide direct evidence for the existence of highly oriented noncrystalline material in these unique PET fibers spun with a threadline modification process. © 1996 John Wiley & Sons, Inc.

关键词： poly(ethylene terephthalate) controlled threadline dynamics orientation oriented noncrystalline phase fiber properties crystallinity

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Bicomponent vascular grafts consisting of synthetic absorbable fibers: Part II: In vivo healing response

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Journal of Investigative Surgery 1994年第3期7卷 195-211页

作者： Yu, Tarng-Jenn Ho, Donald M. Chu, C.C. Section of Cardiovascular Surgery Department of Surgery Veterans General Hospitals-Taipei Institute of Biomedical Engineering Yang-Ming Medical College Shih-Pai Taipei Taiwan Department of Pathology Veterans General Hospitals-Taipei Shih-Pai Taipei Taiwan Department of Textiles and Apparel Cornell University Ithaca NY United States Fiber and Polymer Science Program Department of Textiles and Apparel Cornell University Ithaca NY 14853-4401 United States

The objectives of this research were (I) to determine whether the use of partially absorbable vascular grafts would improve their nonthrombogenic performance and whether they are more prone to aneurysmal dilation and subsequent failure in vivo. and (2) to find out the relationships, if any. between these in vivo and the previously reported in vitro data with an emphasis on how the in vitro changes in fabric structure and properties related to these in vivo data. Bicomponent vascular fabrics were made from Dacron and polyglycolic acid (PGA) yarns with a range of composition ratios of the PGA to Dacron. Both woven and single Jersey knit fabrics were made, and implanted in dogs for 4 months. The following findings and relationships were obtained. (1) The bicomponent vascular fabrics resulted in a full-wall healing in the thoracic aorta of dogs. All bicomponent vascular grafts in survived dogs exhibited 100% patency, no thrombus or aneurysmal formation, no hematoma or seroma around the grafts, and no fibrin coagula in the inner capsules. The gross morphology of the regenerated tissues was very similar visually to the adjacent original arterial tissue. Histologically, the luminal surface was lined with a layer of endothelial cells with myofibroblasts, fibroblasts. and collagens underneath. (2) The extent of the full-wall healing depended on the type of fabric structure. the concentration of absorbable yarns, the location of absorbable yarns (for the woven group only), and initial water permeability. It is believed that the concentration effect was related to the level of macrophage activation from the degradation products of the absorbable yarns, while the location effect was attributed to the various types of fabric structure change on the degradation of the absorbable yarns. (3) In general, the knitted group (K), was better than the woven group (W). K3 showed the best in vivo performance in the knitted group. (4) In the woven group, W3 was the best. The incorporation o

关键词： Absorbable fibers Animal implantation Biodegradation Endothelial cell lining Synthetic vascular grafts Tissue ingrowth

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