GAS-PERMEABILITY AND STRUCTURE OF SULFONATED 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 trimethylsilane) and sulfonated poly(n-xylylene) were studied as a function of the degree of sulfonation. At low degrees of sulfonation (X(s) < 0.2), free films of poly(n-xylylene) are characterized by a symmetrical porous structure with a pore size gradient from the film surface to its inner layer. The films deposited on a support possess an asymmetric porous structure with a homogeneous dense layer adjacent to the support. At high sulfonation degrees (X(s) > 0.6), poly(n-xylylene) films exhibit a homogeneous nonporous structure. For a composite membrane, the structural peculiarities are shown to be responsible for the complicated dependences of carbon dioxide and nitrogen permeabilities on the sulfonation degree and moisture content of the gaseous feed mixtures. The calculated 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.