Abstract
Polymeric membranes for CO2 separation have drawn significant attention in academia and industry. We
prepared amidoxime-functionalized poly(1-trimethylsilyl-1-propyne) (AO-PTMSP) membranes through
hydrosilylation and post-polymerization modification. Compared to neat PTMSP membranes, the
AO-PTMSP membranes showed significant enhancements in CO2/N2 gas separation performance (CO2 permeability
∼6000 Barrer; CO2/N2 selectivity ∼17). This systematic study provides clear guidelines on how to
tune the CO2-philicity within PTMSP matrices and the effects on gas selectivity. Key parameters for elucidating
the gas transport mechanism were discussed based on CO2 sorption measurements and fractional free
volume estimates. The effect of the AO content on CO2/N2 selectivity was further examined by means of
density functional theory calculations. Both experimental and theoretical data provide consistent results that
conclusively show that CO2/N2 separation performance is enhanced by increased CO2–polymer interactions.
