Chain-Straightening Polymerization of Olefins to Form Polar Functionalized Semicrystalline Polyethylene
James M. Eagan, Omar Padilla-Vélez, Kyle S. O’Connor, Samantha N. MacMillan, Anne M. LaPointe, Geoffrey W. Coates
Abstract
We report the design and synthesis of an α-diimine PdII catalyst that copolymerizes functionalized and long chain α-olefins to produce semicrystalline polyethylene materials. Through a chain-straightening polymerization mechanism, the catalyst afforded high-melting point polymers with Tm values of up to 120 °C. The chain-straightening polymerization operates with high [ω,1]-insertion selectivity at high alkene concentrations and with varying α-olefin chain lengths, including propylene. The Pd catalyst can copolymerize 1-decene and methyl decenoate into semicrystalline ester-functionalized polymers with incorporation percentages proportional to the comonomer ratio (up to 13 mol %). 13C nuclear magnetic resonance and isotope labeling studies revealed that the improved selectivity relative to those of other systems arises from a high selectivity for [2,1]-insertion (96%) coupled with rapid chain-walking for a total of 90 mol % of 1-decene undergoing net [10,1]-insertion.