文献类型：期刊文献

英文题名：Conformational changes coupled with the isotropic-anisotropic transition Part 1. Experimental phenomena and theoretical considerations

作者：Lin, JP; Liu, N; Chen, JD; Zhou, DF

机构：[1]E China Univ Chem Technol, Dept Polymer Sci & Engn, Shanghai 200237, Peoples R China

年份：2000

卷号：41

期号：16

起止页码：6189

外文期刊名：POLYMER

收录：;EI(收录号：2000065205390);WOS:【SCI-EXPANDED(收录号:WOS:000087123900019)】；

语种：英文

外文关键词：liquid crystalline polymer; polypeptide; lattice model

摘要：Phase behavior and conformation characteristics were reported for poly(gamma-benzyl-L-glutamate) (PBLG) in dichloroacetic acid (DCA) and a mixed solvent of CHCl3/trifluoroacetic acid (TFA). The anisotopic-isotropic transition, where intramolecular helix-coil transition was coupled, was observed for the PBLG liquid crystal solution prepared, at room temperature, with either a decrease in temperature or an increase in acid content. The information on PBLG molecular conformation provided by TR determinations indicates that in the acid mediated liquid crystal solution, the PBLG side chain may become flexible while the helix backbone remains stable prior to the helix-coil transition. Based on the molecular information gained through the experiments, the reentrant theory previously derived (Lin J. Polymer 1997;38:4837; Lin J. Polymer 1998;39:5495) was further generalized by introducing a temperature-dependent axial ratio of the Kuhn chain. The calculations carried out show an appreciable improvement in the agreement between the theory and the experimental phase diagram. The present theory also accounts, reasonably, for the temperature dependence of the PBLG order parameter observed in the experiments. (C) 2000 Elsevier Science Ltd. All rights reserved.