Copolymerization of ethylene and vinyl fluoride by (phosphine- bis(arenesulfonate))PdMe(pyridine) catalysts: Insights into inhibition mechanisms

摘要

A study was conducted to demonstrate that (Li-OPO)-PdMe(L) and 4-(5-nonyl)-py) catalysts catalyzed the copolymerization of ethylene with VF to yield copolymers with a significantly higher level of vinyl fluoride (VF) incorporation than observed for conventional (PO)-PdMe(py) catalysts. These enabled the characterization of unobserved VF placements in the copolymer and provided insights into the mechanism by which VF inhibited polymerization. Ethylene or VF copolymerizations were carried out using the (Li-OPO)-PdMe(L) and 4-(5-nonyl)-py) as the catalysts at 80 °C in toluene or hexanes. The copolymers produced by (Li-OPO)-PdMe(L) in toluene displayed broad molecular weight distributions, indicative of partial fragmentation of the tetranuclear species and similar to results for ethylene homopolymerization. The copolymers produced by 4-(5-nonyl)-py) in toluene displayed narrower molecular weight distributions, indicative of more extensive catalyst fragmentation.