甲壳型液晶高分子的分子形状和相结构调控:从片状分子到柱状分子和从层状相到柱状相  

Manipulating Molecular Shapes and Phase Structures of Mesogen-Jacketed Liquid Crystalline Polymers:From Sheet-like to Rod-like Molecule and from Smectic to Columnar Phase

作　　者：郑军峰 葛云翀 程晓帆 吴雅婷 徐鹏 陈尔强[2] Jun-feng Zheng;Yun-chong Ge;Xiao-fan Cheng;Ya-ting Wu;Peng Xu;Er-qiang Chen(Department of Applied Chemistry,College of Chemical Engineering,Nanjing Forestry University,Nanjing 210037;Department of Polymer Science and Engineering,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871)

机构地区：[1]南京林业大学化学工程学院应用化学系,南京210037 [2]北京大学化学与分子工程学院高分子科学与工程系,北京100871

出　　处：《高分子学报》2023年第9期1343-1354,共12页Acta Polymerica Sinica

摘　　要：为调控甲壳型液晶高分子(MJLCPs)的分子形状和相结构,以“苯-苄酯-苯”为柔性连接基团设计了一个新的MJCLP 1P,为对比研究,又设计了一个化学结构相似但含有“苯-酯-苯”刚性连接基团的MJLCP 2P.研究结果表明,参考聚合物2P呈现稳定的层状液晶相,其分子形状应为片状构象;目标聚合物1P低温时形成层状液晶相,高温则为柱状液晶相,其分子形状应分别为片状和棒状.本研究提出了1P的分子形状和相转变的机理:低温时,“苯-苄酯-苯”采取反式构象,侧链类似于棒状液晶基元,整个分子为片状,进而形成层状液晶相;高温时,“苯-苄酯-苯”采取旁氏构象,侧链对主链的甲壳效应增加,驱动整个分子为棒状,进而形成柱状液晶相.通过在MJLCPs的侧链中引入“苯-苄酯-苯”柔性连接基团,实现了MJLCPs的分子形状和相结构调控.Aiming at manipulating the molecular shapes and phase structures of mesogen-jacketed liquidcrystalline polymers(MJLCPs)polymers,we designed a new MJLCP 1P containing the flexible“benzene-benzyl ester-benzene”units in its side-chains and another MJLCP 2P as reference containing the rigid“benzene-esterbenzene”units.2P renders extremely stable lamellar liquid crystalline phase probably with sheet-like conformation.However,1P forms lamellar liquid crystalline phase at the low-temperature range and columnar liquid crystalline phase at the high-temperature range,probably with sheet-like and rod-like conformations,respectively.We also proposed the mechanisms for transitions of molecular shapes and phase structures of 1P:at the low temperature range,the“benzene-benzyl ester-benzene”units mainly adopt the tans conformation and hence the side-chains behave like flexible rod-like mesogens,leading to the sheet-like molecules and their further lamellar packing;at the high temperature range,the“benzene-benzyl ester-benzene”units mainly adopt the gauche conformation and thus increases their jacketing effect on the main-chain,generating rod-like molecules and further columnar packing.In this work,through incorporating the flexible connecting units,we successfully manipulated the molecular shapes and phase structures of a MJLCP.This work will pave a way to tune molecular shapes and phase structures of side-chain liquid crystalline polymers.

关 键 词：甲壳型液晶高分子 层状液晶相 柱状液晶相 片状分子 柱状分子 

分 类 号：TQ317[化学工程—高聚物工业] O753.2[理学—晶体学]