Accessing Siloxane Functionalized Polynorbornenes via Vinyl-Addition Polymerization for CO₂ Separation Membranes

Abstract

The vinyl addition polymerization of norbornyl-based monomers bearing polar functional groups is often problematic, leading to low molecular weight polymers in poor yield. Herein, we provide proof-of-principle evidence that addition-type homopolymers of siloxane substituted norbornyl-based monomers may be readily synthesized using the catalyst <i>trans</i>-[Ni(C₆F₅)₂(SbPh₃)₂]. Polymerizations using this catalyst reached moderate to high conversion in just 5 min of polymerization and produced siloxane-substituted polymers with molecular weights exceeding 100 kg/mol. These polymers showed excellent thermal stability (<i>T</i>_d ≥ 362 °C) and were cast into membranes that displayed high CO₂ permeability and enhanced CO₂/N₂ selectivity as compared to related materials.