Diffusion and solution of gases in substituted polyacetylene membranes

The coefficients of permeability, diffusion and solubility ( P, D and S, respectively) of various substituted polyacetylenes for six gases (He, H 2, O 2, N 2, CO 2 and CH 4) at 25°C were determined. The polyacetylenes with a bulky substituent such as poly[1-(trimethylsilyl)-1-propyne] (poly(TMSP)) generally exhibited large P values. The especially large P values (∼ 2 × 10 3−2 × 10 4 barrer) of poly(TMSP) were found to be based on both its D and S values being large. The polyacetylenes with a long n-alkyl group showed fairly large D values, while those with a phenyl group had relatively large S values. The activation parameters for P, D and S ( E P, E D and ΔH S, respectively) were obtained from their temperature dependences (30–70°C). The E P values of poly(TMSP) were all negative (−9.7 to −0.4 kJ mol −1). This stemmed from its small E D values compared with those of other polymers.