Effect of Branching Architecture on Glass Transition Behavior of Hyperbranched Copolystyrenes:the Experiment and Simulation Studies  

作　　者：Xiang Luo Shi-jie Xie 黄卫 Bo-na Dai 吕中元 De-yue Yan 

机构地区：[1]School of Che-mistry and Chemical Engineering,State Key Laboratory of Metal Matrix Composites,Shanghai Jiao Tong University,Shanghai 200240,China [2]Institute of Theoretical Chemistry,StateKey Laboratory of Supramolecular Structure and Materials,Jilin University,Changehun 130021,China [3]Instrumental Analysis Center,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Chinese Journal of Polymer Science》2016年第1期77-87,共11页高分子科学（英文版）

基　　金：financially supported by the National Basic Research Program(Nos.2012CB821500 and 2013CB834506);the National Natural Science Foundation of China(Nos.91127047;21174086 and 21274167)

摘　　要：By controlling the feed ratio of CMS/styrene and the polymerization time, a series of hyperbranched copolystyrenes（HBCPS） were synthesized with comparable weight-averaged molecular weights（Mw） but different degree of branching（DB） through atom transfer radical self-condensing vinyl copolymerization（ATR-SCVCP） with Cu Br/2,2？-bipyridyl as the catalyst. The resulting HBCPS samples were used to investigate the effect of branching architecture on their glass transition behavior. With the DB increased, the glass transition temperatures（Tg） of HBCPS samples measured by DMA and DSC both decreased. Their spin-lattice relaxation times（1H T1r） of protons displayed the same downtrend with increasing DB. Besides, a correlation between the Tgs and the DB was well established by all-atom molecular dynamics（MD） simulations. The values of MD-determined Tgs are little higher than the corresponding experimental ones. However, the dependence of Tgs on DB is in good agreement with the experimental results, i.e., Tg decreases both in experiments and simulations with increasing DB.By controlling the feed ratio of CMS/styrene and the polymerization time, a series of hyperbranched copolystyrenes（HBCPS） were synthesized with comparable weight-averaged molecular weights（Mw） but different degree of branching（DB） through atom transfer radical self-condensing vinyl copolymerization（ATR-SCVCP） with Cu Br/2,2？-bipyridyl as the catalyst. The resulting HBCPS samples were used to investigate the effect of branching architecture on their glass transition behavior. With the DB increased, the glass transition temperatures（Tg） of HBCPS samples measured by DMA and DSC both decreased. Their spin-lattice relaxation times（1H T1r） of protons displayed the same downtrend with increasing DB. Besides, a correlation between the Tgs and the DB was well established by all-atom molecular dynamics（MD） simulations. The values of MD-determined Tgs are little higher than the corresponding experimental ones. However, the dependence of Tgs on DB is in good agreement with the experimental results, i.e., Tg decreases both in experiments and simulations with increasing DB.

关 键 词：All-atom molecular dynamics simulation Degree of branching Glass transition temperature Hyperbranched copolystyrene 

分 类 号：TQ317[化学工程—高聚物工业]