Syndiotactic-enriched propylene-styrene copolymers using fluorenyl-based half-titanocene catalysts

The constrained geometry complexes {3,6-'Bu2C13H6SiMe2N'Bu}TiCl2 (X=Cl, 1; Me, 2), in combination with MAO or borane activators, have been investigated in the copolymerization of propylene with styrene at 25-60 degrees C, 1-5 atm. Both systems were found to give styrene-propylene (PP-PS) copolymers with up to 24 mol% of styrene incorporated and moderate molecular weights (M-w = 14,000-88,000; M-w/M-n = 1.58-2.32). Addition of some ethylene to the styrene-propylene feed improves the catalytic polymerization activity. The PP-PS copolymers feature a syndiotactic-enriched polypropylene microstructure (r > 92%), with randomly distributed single styrene and/or short polystyrene units. (c) 2006 Elsevier B.V. All rights reserved.