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 trans -[Ni(C 6 F 5 ) 2 (SbPh 3 ) 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 ( T d ≥ 362 °C) and were cast into membranes that displayed high CO 2 permeability and enhanced CO 2 /N 2 selectivity as compared to related materials.