GAS-PERMEABILITY AND STRUCTURE OF SULFONA TED POLY(P-XYLYLENE)

The gas separation of a CO2-N2 mixing and the structure of films based on sulfonated poly(n-xylylene) as well as the diffusion and transport properties of a composite membrane based on poly(vinyl trimethylsilan e) and sulfonated poly(n-xylylene) were studied as a function of the d egree of sulfonation. At low degrees of sulfonation (X(s) < 0.2), free films of poly(n-xylylene) are characterized by a symmetrical porous s tructure with a pore size gradient from the film surface to its inner layer. The films deposited on a support possess an asymmetric porous s tructure with a homogeneous dense layer adjacent to the support. At hi gh sulfonation degrees (X(s) > 0.6), poly(n-xylylene) films exhibit a homogeneous nonporous structure. For a composite membrane, the structu ral peculiarities are shown to be responsible for the complicated depe ndences of carbon dioxide and nitrogen permeabilities on the sulfonati on degree and moisture content of the gaseous feed mixtures. The calcu lated and experimental data on the separation factor of the composite membrane with an active layer of sulfonated poly(n-xylylene) (X(s) = 0 .7) with a thickness of 0.3 - 9.0 mum are presented.