SELECTIVE IONIC TRANSPORT IN CATION-EXCHANGE MEMBRANES PREPARED OF SULFO-CONTAINING POLYAMIDES OF VARIOUS COMPOSITION

A study is carried out of the electrochemical and hydration characteri stics of cation-exchange membranes (CEM) prepared of sulfonate-contain ing aromatic polyamides. In polymers, the diamine structure (phenylene diamine, diaminodiphenyloxide, and diaminodiphenylmethane) and the rat io of chloroanhydrides of iso- and terephthalic acids were varied. A s trong effect was found of sulfo-acid fragments in the chain and the co nfigurational composition of the chain on electrochemical properties, transport numbers, and moisture capacity of CE membranes. The conducti vity increases from 10(-5) to 10(-3) Omega(-1) cm(-1) with an increase in the molar fraction of fragments with sulfo groups (from beta = 30 mol % to beta = 80 mol %). The composition is determined of polyamides from which CE membranes with high transport numbers (0.95 - 0.98) and high selectivity with respect to cations of different nature can be p repared. The mechanism of selective electrotransport in membranes prep ared of the studied polyamides is discussed,