检索结果-南通市图书馆

Frontiers of Chemical Science and Engineering 2017年第3期11卷 440-447页

作者： Yang Zhou Phillip Choi Department of Chemical and Materials Engineering University of Alberta Edmonton Edmonton AB T6G 1H9 Canada

Isothermal-isobaric molecular dynamics simu- lation was used to study the diffusion mechanism of water in polyurethane-block-poly（N-isopropyl acrylamide）（PU- block-PNIPAm） with a hydrophobic PU/hydrophilic PNIPAm mass ratio of 1.4 to 1 at 298 K and 450 K. Here, the experimental glass transition temperature （Tg） of PU is 243 K while that of PNIPAm is 383 K. Different amounts of water up to 15 wt-% were added to PU-block- PNIPAm. We were able to reproduce the specific volumes and glass transition temperatures （250 K and 390 K） of PU- block-PNIPAm. The computed self-diffusion coefficient of water increased exponentially with increasing water concentration at both temperatures （i.e., following the free volume model of Fujita）. It suggested that water diffusion in PU-block-PNIPAm depends only on its fractional free volume despite the free volume inhomo- geneity. It is noted that at 298 K, PU is rubbery while PNIPAm is glassy. Regardless of temperature, radial distribution functions showed that water formed clusters with sizes in the range of 0.2-0.4 nm in PU-block- PNIPAm. At low water concentrations, more clusters were found in the PU domain but at high water concentrations, more in the PNIPAm domain. It is believed that water molecules diffuse as clusters rather than as individual molecules.

关键词： molecular dynamics simulation amphiphilic block copolymer free volume water diffusivity fujita model

Ring-opening Metathesis Polymerization of Cis-5-norbornene-endo-2,3-dicarboxylic Anhydride Derivatives Using the Grubbs Third Generation Catalyst

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2017年第1期35卷 36-45页

作者： ji-xing yang 任丽霞 yue-sheng li School of Materials Science and Engineering and Tianjin Key Laboratory of Composite and Functional Materials Tianjin University Tianjin 300072 China

A series of cis-5-norbornene-endo-2,3-dicarboxylic anhydride （NDCA, M1） derivatives （M2-M4） with different types of nonpolar substituted groups were synthesized and characterized by 1H/13C-NMR and mass spectrometry （MS）. Ring- opening metathesis polymerization （ROMP） of these monomers using the Grubbs third generation catalyst （G3） generated high molecular weight polymers with much improved solubility compared with the NDCA＇s homopolymer. It was found that the solubility of these polymers increased with increased substituent＇s steric hindrance. The living polymerization of NDCA derivative containing the bulkiest substituent （M4） catalyzed by G3 in tetrahydrofuran was confirmed by the kinetic studies with low polydispersity indices （PDI）（〈 1.30）. By using sequential ROMP, well-defined diblock copolymers containing anhydride groups were synthesized.

关键词： Living polymerization Ring-opening metathesis polymerization amphiphilic block copolymer Anhydridegroup

PEGYLATED SINGLE-WALLED CARBON NANOTUBES WITH GELABLE block copolymerS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2011年第6期29卷 762-771页

作者：陈永明 Laboratory of Polymer Physics and Chemistry Institute of Chemistrythe Chinese Academy of Sciences

Functional amphiphilic block copolymer poly（ethylene glycol）-block-poly[（3-（triethoxysilyl）propyl methacrylate）- co-（1-pyrene-methyl） methacrylate], PEG113-b-P（TEPM26-co-PyMMA4）, was synthesized via atom transfer radical polymerization （ATRP） initiated by monomethoxy capped poly（ethylene glycol） bromoisobutyrate. This polymer exhibited strong ability to disperse and exfoliate single-walled carbon nanotubes （SWNTs） in different solvents due to the adhesion of pyrene units to surface of SWNTs. In aqueous solution, the PTEPM segments that were located on the nanotube surfaces with the pyrene units could be gelated and, as a result, the silica oxide networks with PEG coronas were formed on the surface of nanotubes, which ensured the composites with a good dispersibility and stability. Furthermore, functional silane coupling agents, 3-mereaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, were introduced during dispersion of SWNTs using the block copolymers. They were co-gelated with PTEPM segments, and the --SH and --NH2 functionalities were introduced into the silica oxide coats respectively.

关键词： amphiphilic block copolymer Functionality PEGylated Single-walled carbon nanotubes

Influence of block copolymer on Formation and Acid Resistant Properties of Hybrid CaCO_3 Particles

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2009年第1期25卷 112-115页

作者： LI Xiao-dong HU Qiao-ling ZHAO Shi-fang SHEN Jia-cong Affiliated Stomatology Hospital Zhejiang University College of Medicine Hangzhou 310058 P. R. China Institute of Polymer Composite Zhejiang University Hangzhou 310027 P. R. China

block copolymer polystyrene-b-poly（acrylic acid）（PS-b-PAA） was used as structural template for the synthesis of CaCO3 microparticles. Through this procedure, acid resistant hybrid CaCO3 micro- spheres were obtained. Acid resistant properties of this type of hybrid CaCO3 were studied. Size measurement shows that the acid resistant properties of the hybrid particles are different in different solutions, such as HCl, EDTA, and H2SO4 solutions.

关键词： amphiphilic block copolymer Hybrid particle Size control Acid resistance

Metal-free synthesis of amphiphilic functional polycarbonates

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2007年第12期18卷 1528-1530页

作者： Ying Xia Wang Jun Feng Feng He Ren Xi Zhuo Key Laboratory of Eco-textiles （Jiangnan University） Ministry of Education Wuxi 214122 China Department of Chemistry Key Laboratory of Biomedical Polymers of Ministry of Education Wuhan University Wuhan 430072 China

amphiphilic block copolymers of poly（5-benzyloxy trimethylene carbonate）（PBTMC） and poly（ethylene glycol）（PEG） were synthesized through enzymatic polymerization using immobilized porcine pancreas lipase （IPPL）. The obtained copolymers with different compositions were characterized by GPC and IH NMR. The copolymer composition was in agreement with the feed ratio. The molecular weight of the copolymers showed an increasing trend with the decrease of PEG contents. MiceUes of the copolymers were formed by dialysis procedure, and characterized by transmission electron microscopy （TEM）.

关键词： amphiphilic block copolymer Enzymatic polymerization Polycarbonate

Synthesis and Self-assembly Behavior of Chiral amphiphilic Diblock copolymers Bearing L-phenylalanine

在线全文

学校读者我要写书评

暂无评论

Synthesis and Self-assembly Behavior of Chiral Amphiphilic D...

Self-assemble of amphiphilic block poly（acrylamide）

2011 International Conference on Smart Materials and Nanotechnology in Engineering (SMNE 2011)

作者： Yong Zhou Bing Liu College of Chemistry and Chemical engineering Xinxiang University

Novel chiral amphiphilic diblock copolymers bearing L-phenylalanine was synthesized using a "click" reaction of N3-L-phenylalanine and MPEO-b-PGPE. The structure and composition of copolymers were characterized by 1H-NMR and elemental analysis. Additionally, the selfassembly behavior of these chiral copolymers was investigated in sodium dihydrogen phosphate buffer（p H 4.5）: the CMC of copolymer MPEO-b-PGTP determined by the measurement of surface tension was 2.1 mg/m L;the size and morphology of the micelles were studied using TEM;the specific optical rotation（[α]25D） of the micellar solutions was also measured;the result indicated that the copolymers can form chiral micelles in sodium dihydrogen phosphate buffer（p H =4.5）.

关键词： "Click" reaction amphiphilic block copolymer chiral micelles

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Self-assemble of amphiphilic block poly（acrylamide）