Catalyst systems for syndiospecific polymerization of styrenes

摘要

Syndiotactic polystyrene is produced in the presence of a catalyst comprising:PP(i) trimethylaluminum,P P(ii) at least one of the organotin compounds with general formulae:P PR.sub.1 R.sub.2 R.sub.3 Sn--O--SnR.sub.4 R. sub.5 R.sub.6 P Por R.sub.1 R.sub.2 R.sub.3 Sn--OHP Por R.sub.1 R. sub.2 SnOPPor R.sub.1 Sn(O)OH; PP wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R. sub.6 are the same or different C.sub.1 -C.sub.20 alkyl groups or aryl groups or alkylaryl groups,PP(iii) one or several derivatives of transition metals having the formula Cp.sub.n MA.sub.m-n, wherein M is a metal selected from the group of titanium, zirconium and hafnium, Cp is a cyclopentadienyl or a substituted cyclopentadienyl group; n is 0, 1 or 2; m is 4 or 3; and A is selected from the group consisting of a halogen, hydrogen, or an oxyhydrocarbyl group OR', wherein R' is a C. sub.1 -C.sub. 6 linear or branched alkyl group, a substituted or non- substituted aryl group, or an arylalkyl group.