Hydration and ion-exchange processes in carboxylic membranes

Abstract

An infrared investigation has been performed on totally neutralized membranes of poly(acrylic acid) grafted on a Teflon FEP or PTFE matrix. The changes in the principal absorption bands characterizing the vibration modes of the carboxylate group and water in Li⁺, Na⁺ and K⁺ salt membranes are analysed as a function of the degree of humidity and of the exchange capacity. The strength of the hydrogen bonding between water and the carboxylate ion and the nature of the ionic interactions in the membrane are discussed.