1-(4-二甲基硅氢苯基)-1-苯乙烯/异戊二烯的活性阴离子交替共聚合调控研究

采用活性阴离子聚合方法研究了硅氢基功能化的1,1-二苯基乙烯(DPE)衍生物1-(4-二甲基硅氢苯基)-1-苯乙烯(DPE-SiH)与异戊二烯(Ip)在苯中的共聚反应,采用多种方法对序列分布、竞聚率和表观速率常数等进行测定.结果表明无调节剂下共聚物链中异戊二烯的插入量远多于DPE-SiH,DPESiH主要分布在聚合物链末端,得到了一种梯度共聚物,竞聚率rIp=9.28,2种单体的表观速率常数分别为KD=0.00134 min^?1,KIp=0.01421 min^?1,Ip在无调节剂条件下的共聚中表现出高活性.同时研究了添加调节剂(N′N'N'N-四甲基乙二胺(TMEDA)和叔丁醇钾(t-BuOK))后的共聚物链中的序列分布,加入调节剂TMEDA和t-BuOK后得到了交替共聚物,实现了DPE-SiH和Ip单元在共聚物链中的序列调控,且对链中Ip单元的微观结构含量进行了调控,对形成交替共聚物的原因做了探讨,并通过Gaussian模拟探究了活性中心对Ip微观结构具有选择性的机理以及调节剂对活性中心的作用机理.

Study on the Regulation of Living Anionic Alternating Copolymerization of 1-(4-Dimethylsiloxphenyl)-1-styrene and Isoprene

The alternating regulation of living anionic copolymerization of 1-(4-dimethylsiloxphenyl)-1-styrene(DPE-SiH)and isoprene(Ip)was studied.By combining in situ 1H-NMR with MALDI-TOF MS technologies,the sequence distribution and apparent rate constant of monomers in the copolymer,as well as the reactivity ratio of Ip were determined.The results showed that the amount of DPE-SiH unit entering in the copolymer was less than that of Ip,and the site of DPE-SiH unit was mainly gathered at the end of copolymer when without the addition of regulators.Meanwhile,the gradient copolymer was obtained with the reactivity ratio rIp=9.28.The apparent rate constants of DPE-SiH and Ip unit were KD=0.00134 min^?1 and KIp=0.01421 min^?1,respectively.In addition,the sequence distribution characteristics of the two monomers in the copolymer chain after the addition of the regulatorsN'N'N'N-tetramethylethylenediamine(TMEDA)and potassium tert-butoxide(t-BuOK)]were investigated.The copolymer with the alternating sequence feature was obtained when the regulator TMEDA and t-BuOK were added,achieving the sequence control of DPE-SiH and Ip unit in the copolymer chain.Meanwhile,the alternating entry of two monomers in the copolymer chain and the improvement of trans-1,4 Ip contents of copolymer were attributed to the“space-limited”living species resulted by the addition of regulators according to the results of Gaussian simulation.