β-二酮钛配合物／MAO催化苯乙烯与ρ-甲基苯乙烯的间规共聚

Syndiotactic Copolymarization of Styrene and ρ-methylstyrene Via β - diketonate Titanium Complex/MAO

三（二苯甲酰甲烷）苯氧基钛酸酯[（dbm）3Ti（OPh）]在MAO作用下，催化P-甲基苯乙烯间规聚合，讨论了催化剂浓度、铝钛比和聚合温度对反应的影响，如在催化剂浓度为350μmoL／L，铝钛比为500时聚合活性为7．5×10^5g／molTi·h。聚合物有两个熔点183℃、203分别对应晶型Ⅰ、Ⅲ，玻璃化转变温度为108℃左右。同时考察了在此催化体系下P-甲基苯乙烯与笨乙烯的间规共聚，笨乙烯竞聚率r1=0．287，P-甲基苯乙烯竞聚率r2=1．806。r1×r2=0．518。

The syndiotactic polymarization of p - methylstyrene was carried out with （ dibenzoylmethanato ） 3 Ti （ OPh ） [ （dbm）3Ti （OPh）] /methylaluminoxane （MAO） catalytic system. The copolymerization of p- methylstyrene and styrene was also investigated using this catalyst system. The ^13 C - NMR spectra of these homopolymers and copolymers indicated that the polymers were highly syndiotactic. The polymerization activity for p - methylstyrene depended on the polymerization conditions. When the C （Ti） was 350μmol/L, and the Al/Ti molar ratio was 500, polymerization activity was up to 7. 5×10^5gPPMS/molTi·h, reached the maximum value. The polymerization activity was increased with the enhancement of temperature from 20℃ to 100℃. But the syndiotacticity and the melting temperature were decreased in the certain range. In copolymerization of p - methylstyrene and styrene, the monomer reactivity ratios were estimated by using the Fineman - Ross methed r1 = 0. 287, r2 = 1. 806, r1×r2 = 0. 518.