ELECTROCHEMICAL PROPERTIES AND HYDRATION OF CATION-EXCHANGE MEMBRANESBASED ON SULFONATE-CONTAINING POLYETHYLENEPHTHALAMIDES

Electrochemical characteristics and hydration behavior of cation-excha nge membranes based on sulfonate-containing aromatic polyamides were s tudied. These polyamides were synthesized via condensation of sodium 4 ,4'-diaminophenylamino-2-sulfonate and m-phenylenediamine, taken in di fferent ratios, with isophthaloyl chloride. Electroconductivity, trans port numbers, and water regain of the cation-exchange membranes were s tudied as a function of the molar content of the chain fragment contai ning a sulfo-group (a = = 30 - 100 mol %). On increasing the molar fra ction of this fragment from 30 to 50 - 60 mol %, a sharp growth in ele ctroconductivity from 10(-5) to 10(-3) OMEGA-1 cm-1 was observed. When the molar content was < 70 mol %, electroconductivity was shown to de pend on the nature of the cation and tended to decrease in the followi ng order: Na+ > K+ > Cs+ > Li+. The polymer composition of a polyamide -based cation-exchange membrane, which corresponds to high transport n umbers (0.95 - 0.99) and high transport selectivity of various cations , was determined.