Chain-Straightening Polymerization of Olefins to Form Polar Functionalized Semicrystalline Polyethylene

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.