Tri-alkenyl polyhedral oligomeric silsesquioxanes as comonomers and active center modifiers in ethylene copolymerization catalyzed by bis(phenoxy-imine) Ti, Zr, V and V salen-type complexes

Abstract

In copolymerization of ethylene (E) with tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) were used bis(phenoxy-imine) titanium, zirconium and vanadium catalysts, as well as salen-type vanadium catalysts. There were obtained copolymers with POSS-R-3 units as side branches of polymer chains. The type of employed bis(phenoxy-imine) titanium, zirconium and vanadium catalysts and salen-type catalyst of vanadium determined the copolymer chain termination reactions, as well as the mechanism of modification of the active species by the POSS-R-3 comonomer. POSS-R-3 comonomers caused selective poisoning of bis(phenoxy-imine) zirconium catalyst and they provided protection against tight contact with [Me-MMAO]− counter anion. Concentration of the precursor of the active site and Ti(III) complex was found decreased in the system with bis(phenoxy-imine) titanium catalyst and POSS-R-3. There were formed different catalytic species characterized by diamagnetic properties for bis(phenoxy-imine) vanadium due to the presence of POSS-R-3. Our findings were based on results from the following methods: FT-IR, 1H NMR, 1H-1H NOESY, EPR and GPC.