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

Graphical abstract: - Highlights: • Three novel polyphenylacetylene gas separation membranes were synthesized. • The copolymers adopted one-handed helical conformations. • The separation selectivity factor of CO₂/N₂ was 17.9. • The CO₂ permeability coefficient of CO₂/N₂ was 77 Barrers. - Abstract: 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 M_w 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