Use of Vanadium Complexes Bearing Naphthalene-Bridged Nitrogen-Sulfonate Ligands as Catalysts for Copolymerization of Ethylene and Propylene

Vanadium complexes bearing naphthalene-bridged nitrogen-sulfonate ligand ([ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VOCl (1a) and [ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VCl2(1b)) were synthesized. Activated by ethylaluminium sesquichloride (EASC) and in the presence of ethyl trichloroacetate (ETCA) as reactivator, complexes1aand1bshowed activities of up to 39.1 kg polymer (mol V)−1h−1, affording the copolymers with high molecular weights (Mwup to 28 × 104) and narrow molecular weight distributions (Mw/Mn~ 3.0) as well as high propylene incorporation of up to 49.4%. Compared to the traditional VOCl3system, these complexes exhibited higher propylene incorporation ability and higher catalytic activities especially at high polymerization temperatures of 50 °C and above. Determined by DSC and13C NMR, the copolymers obtained with1aand1bhad more random structures than that with the VOCl3system.Keywords:vanadium catalyst;ethylene/propylene copolymerization;polyolefin