Synthesis and gas transport properties of new copolymer membranes with trimethylsilyl groups

Copolymers of 3-methacryloxypropyl tris(trimethylsiloxy) silane (SiMA) with methacrylate (MMA) and copolymers trimethylsilyl methyl methacrylate (TMSMMA) with vinyl acetate (VAc) were synthesized by radical polymerization. Membranes were cast from their solutions. Gas permeability, 10-1000 Barrer, of SiMA-MMA membranes was higher than that of TMSMMA-Vac membranes because of higher concentration of trimethylsilyl groups. Both apparent activation energies for gas permeability were very small compared to those of ordinary polymeric membranes. Poly(SiMA) is rubbery and poly(TMSMMA) is glassy at an ambient temperature. Copoly(SiMA-MMA) and copoly(TMSMMA-VAc) were shown to be random copolymers by the relationship between gas permeability coefficients and the molar ratio of each monomer. A series of copolymers in this investigation was shown to be a rare case of the polymer of which gas permeability increased in spite of the larger side chain, trimethylsilyl group, being introduced in the polymer chains.