Syndiospecific living polymerization of propene with [t-BuNSiMe(2)Flu]TiMe2 using MAO as cocatalyst

Propene polymerization was conducted at 0 degreesC by [t-BuNSiMe(2)Flu]TiMe 2 combined with B(C6F5)(3), MAO, or the MAO which had been dried in a vacuu m and washed with hexane before use. The effect of cocatalyst cocatalyst wa s investigated under atmospheric pressure of propene in a semibatch system where polymerization rate was followed by the amount of propene consumed. T he B(C6F5)(3) system was deactivated within 30 min, while the MAO system sh owed steady polymerization rate. On the other hand, the activity of the dri ed MAO system was so high that the kinetic profile could not be evaluated p recisely. The MAO system gave the low molecular weight polymer, and the num ber of polymer chains was more than 10 times higher than the amount of tita nium complex employed. In the dried MAO system, however, the produced polym er showed the highest molecular weight and narrowest molecular weight distr ibutions of about 1.2. The batchwise polymerization with the dried MAO syst em indicated that propene polymerization proceeded quantitatively regardles s of the monomer charged, and the number-average molecular weight of the po lymer obtained increased linearly against the polymer yield with Beeping th e molecular weight distribution narrow and the number of polymer chains con stant. The results of postpolymerization testified that living polymerizati on proceeded under these conditions. The C-13 NMR measurement indicated tha t syndiotactic-rich polypropenes were produced in a highly regiospecific ma nner by this catalyst system.