线型三嵌段共聚物PSI-PIB-PSI的合成与性能

采用阴离子聚合方法，自制的双锂引发剂，环己烷为溶剂，两步法合成出线型三嵌段共聚物：苯乙烯异戊二烯无规共聚物-丁二烯异戊二烯共聚物-苯乙烯异戊二烯无规共聚物（PSI-PIB-PSI）。采用¹H-NMR研究了微观结构及共聚组成，透射电镜（TEM）观察了聚合物的形态，动态粘弹性仪(DMTA)对热机械性能进行了测试。结果表明：当四氢呋喃与活性中心锂的物质的量比（R值）为60时，可实现异戊二烯-苯乙烯(I-S)的无规共聚；TEM图表明聚合物PSI-PIB-PSI为两相结构，且随着苯乙烯（St）的含量的增加，相分离现象明显；当PIB/PSI的嵌段质量比为1/2，苯乙烯的质量分数为27%～28%时，该线型三嵌段共聚物具有最佳的综合力学性能。

Synthesis and properties of the linear triblock copolymer poly (isoprene-ran-styrene) - ( butadiene-ran-isoprene)-(isoprene-ran-styrene) (PSI-PIB-PSI)

A new type of linear triblock copolymer,poly(isoprene-ran-styrene)-(butadiene-ran-isoprene)-(isoprene-ran-styrene)(PSI-PIB-PSI) has been synthesized in two steps by continuous anionic polymerization techniques using a novel dilithium initiator.The microstructures and composition of the copolymers were characterized by nuclear magnetic resonance(NMR) and their morphologies and dynamic mechanical properties were determined by transmission electron microscopy(TEM) and dynamic mechanical thermal analysis(DMTA).NMR spectroscopy showed that poly(isoprene-ran-styrene) was formed when the molar ratio(R) of : was 60.The copolymers show two phase states and this phenomenon was more marked for higher styrene contents.The copolymers were found to have the optimum combination of mechanical properties for a styrene content of 27%-28% and a PIB/PIS ratio of 1/2.