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

摘要

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, complexes >1a and >1b showed activities of up to 39.1 kg polymer (mol V)⁻¹ h⁻¹, affording the copolymers with high molecular weights (Mw up 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 VOCl3 system, these complexes exhibited higher propylene incorporation ability and higher catalytic activities especially at high polymerization temperatures of 50 °C and above. Determined by DSC and ¹³C NMR, the copolymers obtained with >1a and >1b had more random structures than that with the VOCl3 system.