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

The constrained geometry complexes {3,6-tBu2C13H6SiMe2NtBu}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 °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 (Mw = 14,000–88,000; Mw/Mn = 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.

Graphical abstractThe constrained geometry complexes {3,6-tBu2C13H6SiMe2NtBu}TiX2 (X = Cl, 1; Me, 2), in combination with MAO or borane activators, efficiently copolymerize propylene and styrene in the presence of small amounts of ethylene to afford styrene–propylene (PP–PS) copolymers with a syndiotactic-enriched polypropylene microstructure and randomly distributed single styrene or short polystyrene units. Figure optionsDownload full-size imageDownload as PowerPoint slide