高分子玻璃化转变的链长依赖性  

Chain Length Dependence of Glass Transition in Polymers

作　　者：罗锦添 徐全印 徐文生 左彪[1] Jin-tian Luo;Quan-yin Xu;Wen-sheng Xu;Biao Zuo(School of Chemistry and Chemical Engineering,Key Laboratory of Surface&Interface Science of Polymer Materials of Zhejiang Province,Zhejiang Sci-Tech University,Hangzhou 310018;Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022)

机构地区：[1]浙江理工大学化学与化工学院、浙江省高分子材料表界面科学重点实验室,杭州310018 [2]中国科学院长春应用化学研究所,长春130022

出　　处：《高分子学报》2025年第4期539-550,共12页Acta Polymerica Sinica

摘　　要：玻璃化转变的微观机制是凝聚态物理最重要的科学问题之一.由于链的连通性,高分子表现比小分子物质更复杂的玻璃化行为.本综述对半个多世纪以来,科学家对高分子玻璃化转变链长依赖性的研究进行了总结.介绍了高分子玻璃化温度(T_(g))和脆度指数(m)等性质随链长增加而增大并趋于饱和的普遍现象;总结了解释和描述T_(g)和m随链长变化的3种主要机制:即高运动活性链末端促进高分子协同运动,从而降低T_(g)和m;局部链刚性随链长增加而增大从而减弱链段运动能力,使T_(g)升高;分子链内次级松弛单元的耦合和动态促进激活链段松弛,造成T_(g)随链长增大而增大.希望通过对高分子玻璃化现象和机理的总结与讨论帮助读者加深对长链大分子玻璃化转变的认识和理解.Glass transition is one of the most important properties of condensed matter.Chain connectivity endows polymers with complex glass transition behaviour that varies with the chain length.We have summarized more than half a century of research on the chain length dependence of glass transition of polymers.In the first part,we discussed the general phenomenon of the increase in glass transition temperature(T_(g))and dynamical fragility(m)with increasing chain length until they reach saturation values.In the second part,the mechanisms proposed in the past decades to explain the general behaviour of the polymer glass transition were reviewed,including(1)the chain end effect,i.e.,the chain ends associated with extra mobility and excess conformational freedom play a role in accelerating segmental movement and lowering polymer T_(g);(2)the chain stiffness effect,i.e.,the polymer chains stiffened as the molecular weight increased,leading to an increase in T_(g) with chain length before reaching the thresholds;(3)intramolecular coupling effect,i.e.,dynamic couplings of secondary relaxations along the chains facilitate the segmental relaxation,leading to an increase of T_(g) with the chain length.We hope this review helps the readers gain a deeper understanding of the glass transition of polymers and the associated molecular mechanisms.

关 键 词：玻璃化转变 链长依赖性 端基效应 链刚性 链内耦合 

分 类 号：O631[理学—高分子化学]