A method for preparing a diene polymer or copolymer having increased amounts of 1,2-microstructure is provided. The method involves polymerizing a diene monomer or mixture of a diene monomer and a vinyl aromatic hydrocarbon monomer in a hydrocarbon solvent in the presence of a catalytically effective amount of a catalyst composition comprising: (a) an organolithium initiator and (b) an oxolanyl cyclic acetal having the structural formula:
wherein R is selected from the group consisting of hydrogen and alkyl groups containing from 1 to 4 carbon atoms and X is 0 or 1.
本发明提供了一种制备具有更多 1,2-微结构的二烯聚合物或共聚物的方法。该方法包括在烃溶剂中,在催化有效量的催化剂组合物存在下,聚合二烯单体或二烯单体与
乙烯基芳香烃单体的混合物,该催化剂组合物包括:(a)
有机锂引发剂和 (b) 具有结构式的氧杂环
缩醛:
其中 R 选自氢和含 1 至 4 个碳原子的烷基组成的组,X 为 0 或 1。