新型abc三嵌段液晶共聚物的合成及表征.pdf

湘潭大学硕士学论文黄孝华 II Abstract The literature reporting the r ecently researches of block copoloymers, especially the rod-coil triblock copolymers were briefly summarized in this dissertati on. A series of novel ABC mesogen-jacketed liquid-crysta l triblock copolymers with poly{2,5-bis[(4-methoxyphenyl)oxy cabony] styrene}(PMPCS) as rod block were designed and synthesi zed by atom transfer radical polymerization (ATRP) and its pha se behavior was discussed. 1. The macromolecular initiators PEO-Br, bromo-terminated PEO was prepared by esterification be tween PEO and 2-bromoisobutyryl bromide. The ATRP of an amphiphilic diblock copolymer PEO-b-PS was acchived using CuBr/bpy as catalyst system. The crystalline behavior of PEO block in th e copolymer was studied using differential scanning calorimetry(DSC) 、 polarized optical microscope(POM). It showed th at the crystalizing velocity, crystallinity degree and crystalline pe rfection of PEO decreased as the content PS increased. Even there was no crystallization of PEO block. 2. A series of ABC triblock rod-coil liquid-crystalline copolymers with controlled molecular weight and narrow molecular weight distribution were obtained by ATRP using PEO-b-PS-Br as macroinitiators and CuBr/sparteine complex as catalyst system. Gel permeation chromatography(GPC) and 1 HNMR were used to confirmed the structure of r od-coil block PMPCS. The liquid crystalline of this block copolymer was characterized by differential 2 提要近几年来,随着现代科学技术的飞速发展高分子科学也得到了前所未有的发展。人们对高分子材料的需求也从过去具有单一性能的高聚物转而向具有各种综合性能或具有各种特殊用途的高分子材料的需求,由于嵌段共聚物具有许多与众不同的性能而受到人们极大的关注。嵌段共聚物的研究起始于无终止阴离子活性聚合的发现,适当的 A 、 B 单体顺次阴离子聚合便制备出最简单的 AB 二嵌段共聚物[1] , 制备嵌段共聚物的方法包括活性离子聚合、开环聚合、缩聚及自由基聚合,但由于制备成本高,反应条件苛刻,只有如 SBS 和 ABS 等这样为数不多的嵌段共聚物进入市场。自由基可控聚合用于合成嵌段共聚物己有一段历史,但 90 年代以前报道的自由基方法合成的嵌段共聚物中或多或少都有均聚物的存在。 90 年代初发展起来的 TEMPO ·及 Co Ⅱ·存在下的可控自由基聚合虽可合成嵌段共聚物, 但存在两大致命的缺点。一是 TEMPO ·只能合成苯乙烯类单体共聚物, Co Ⅱ· 只能合成丙烯酸酯类嵌段共聚物; 二是不论是 TEMPO · 还是 Co Ⅱ·存在下的体系,都较难得到双官能团的引发剂,因而不是很容易直接制得三嵌段共聚