ИСТИНА

A number of 22 polyheteroarylenes including 18 polyimides, divided in five series, were studied with regard to the dependence of permeability, diffusion and solubility coefficients of gases on the reverse value of fractional accessible volume. It was shown that all these dependences are linear in semilogarithmic coordinates. Thus, the overal selectivity, which is determined by the slope of these dependences, is correlated with the free volume in each series of polymers. The introduction of volumetric bridging groups into the diamine component with the possibility of rotation around bonds with the polymer backbone near the bridge leads to an increase in the overall selectivity of permeability, diffusion and solubility of the polymer at sufficiently high values of the permeability, diffusion and solubility coefficients. It was shown that the study of the system one – polymer different gases allows to differentiate the polymers in function of the overall selectivity of permeability, diffusion and solubility. The overall selectivity depends on the free volume of the polymer. Detailed analysis of the overall selectivity of the polymers showed that the van der Waals volume of the bridge in the diamine component of the polyimide monomer unit along with the conditions of the rotation around the bridge bonds with the main chain, has a great influence on the characteristics of the transport polymer. The bridging group in the dianhydride component is also of great importance