稀土催化乙烯/苯乙烯链穿梭共聚合  

Chain Shuttling Copolymerization of Ethylene and Styrene Catalyzed by Rare-earth Metal Complexes

作　　者：黄立贤 刘波[1,2] 崔冬梅[1,2] Li-xian Huang;Bo Liu;Dong-mei Cui(State Key Laboratory of Polymer Physics and Chemistry,Changchun Institue of Applied Chemistry,Chinese Acadamy of Sciences,Changchun 130022;School of Applied Chemistry and Engineering,University of Science and Technology of China,Hefei 230026)

机构地区：[1]中国科学院长春应用化学研究所,高分子物理与化学国家重点实验室,长春130022 [2]中国科学技术大学应用化学与工程学院,合肥230026

出　　处：《高分子学报》2021年第5期514-521,共8页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21634007,51673184)资助项目.

摘　　要：链穿梭聚合作为一锅法合成多嵌段聚合物的策略引起人们的研究兴趣.然而,其催化体系的构建难度大,导致实现链穿梭聚合的单体有限.本文基于三异丁基铝作链转移剂时,稀土金属配合物1催化乙烯/苯乙烯共聚合,得到富含乙烯/苯乙烯交替序列的共聚物且链转移效率接近100%的发现,开展了乙烯/苯乙烯链穿梭聚合的研究.首先探索配合物2催化乙烯/苯乙烯共聚合,发现所得共聚物中苯乙烯结构单元的含量<4%,因此考察了在不同烷基铝用量时,配合物2催化乙烯均聚合的行为,发现所得聚乙烯的分子量随着[Al]_(0)/[2]_(0)增加呈指数降低,幂指数为−0.778,表明链转移效率低于100%.采用1/2/AliBu3三元体系催化乙烯/苯乙烯共聚合得到双峰分布的聚合物,说明链穿梭聚合没有实现.进一步筛选发现,配合物3催化乙烯/苯乙烯共聚合时,随着[Al]_(0)/[3]_(0)增加,所得富间规聚苯乙烯序列共聚物的分子呈量指数降低,幂指数为−1.097,接近−1,表明链转移效率接近100%;同时催化体系的TOF值减小.当[AliBu3]_(0)/[1+3]_(0)≥20时,1/3/AliBu3三元体系催化乙烯/苯乙烯共聚合得到单峰分布的乙烯/苯乙烯交替序列和富间规聚苯乙烯序列的多嵌段共聚物,说明成功实现了乙烯/苯乙烯链穿梭共聚合.通过调节1和3的比例,有效调控了共聚物中乙烯/苯乙烯交替序列和富间规聚苯乙烯序列的组成.As a facile strategy for one pot synthesis of multiblock polymers,chain shuttling polymerization has aroused considerable attention.However,the construction of the corresponding catalytic system is difficult,leading to the limited number of monomers to successfully achieve chain shuttling polymerization.Herein,we conducted the investigation of chain shuttling polymerization of ethylene and styrene on the basis that in the presence of AliBu3,rare-earth metal complex 1 catalyzed the copolymerization of ethylene and styrene to give the alternating sequence enriched copolymer with the chain transfer efficiency of 100%.Firstly,complex 2 was employed to catalyze the copolymerization of ethylene and styrene.The styrene content of the afforded copolymer is less than 4%.Thus,ethylene polymerization was conducted under various ratios of[Al]_(0) to[2]_(0).The molecular weight of the afforded polyethylene exponentially decreased with the increase of[Al]_(0)/[2]_(0) with the power of−0.778,suggesting that the chain transfer efficiency is less than 100%.The ternary catalytic system composed of 1,2 and AliBu3 catalyzed the copolymerization of ethylene and styrene to afford copolymers with bimodal molecular weight distributions,indicating the unsuccess of chain shuttling.Then after screening a series of complexes,3 was found to catalyse the copolymerization of ethylene and styrene with the chain transfer efficiency of 100%as the molecular weights of the afforded copolymers syndiotatic polystyrene sequence enriched exponentially decreased with the increase of[Al]_(0)/[3]_(0) with the power of−1.097.When the ratio of[AliBu3]_(0) to[1+3]_(0) was no less than 20,the ternary catalytic system composed of 1,3 and AliBu3 catalyzed the copolymerization of ethylene and styrene to afford multi-block copolymers containing alternating sequences and syndiotactic polystyrene sequences with unimodal molecular weight distributions,indicating the success of chain shuttling.The sequence distribution was effectively controlled by adjusting the

关 键 词：链穿梭聚合 稀土金属配合物 序列可控聚合 乙烯 苯乙烯 

分 类 号：TQ316.314[化学工程—高聚物工业]