Copolymerizations of chiral phenylacetylenes having an L-amino alcohol residue and an achiral phenylacetylene having a dodecyl group, used as gas separation membranes

Three chiral phenylacetylenes having an l-amino alcohol residue and two hydroxymethyl groups and an achiral phenylacetylene having two hydroxyl groups and a dodecyl group were copolymerized by using an achiral catalyst ((nbd)Rh+[η6-(C6H5)B−(C6H5)3]) (nbd = norbornadiene) to produce copolymers with Mw of 0.5 × 104–15.2 × 104. The copolymers exhibited the Cotton effect at wavelengths assignable to the main chain, indicating that the copolymers adopted one-handed helical conformations. Self-supporting membranes of the resulting copolymers were prepared by the solution casting method. We measured the gas permeabilities (CO2/N2, CO2/CH4) of the copolymer membranes. The separation selectivity factor of CO2/N2 was 17.9, and the CO2 permeability coefficient of CO2/N2 was 77 Barrers.