CHEMICAL-STRUCTURE AND GAS-SEPARATING PROPERTIES OF AROMATIC POLYESTERIMIDES MEMBRANES

Correlation between chemical structure and transport properties Of compositional membranes with the elective layer from some aromatic polyesterimides (PEI) on the microporous carrier from poly(2,6-dimethyl-1,4-phenyloxide) prepared in standard conditions has been studied. Introducing of hinge -O- groups into PEI with dianhydride fragments of various structure decreases the separation selectivity with slight increase of gasopermeability. The transition from hinge -O- to bulk bridge groups (-SO2- and -C(CF3)2) permits to attain the optimal combination of gasopermeability and selectivitY of separation. These characteristics for He/N2 and O2/N2 gases pairs correlate with the packing density and intramolecular segmental mobility of macromolecular Introducing of oligodimethylsiloxane units into PEI results in decreasing of selectivity and increasing of gasopermeability of membranes because of the two-phase morphology of such copolyimides and predominant transport of gases throughout the phase containing siloxane fragments. The dependence of values of coefficients of diffusion of He and Ar on MM of the polymer has been studied. For M(w) greater-than-or-equal-to (12-14).10(3) the transport properties are shown to be constant.