Low angle X-ray study of the phase state of water in perfluorinated ion-exchange membranes☆

Abstract It is now known [1–3] that perfluorinated sulphocationite ion-exchange membranes (PSMs) have a heterogeneous microstructure. These membranes are in the form of an amorphous matrix containing a small amount (3–15%) of crystalline phase. It is clear that when the crystallinity values are so low, properties of the membranes as ion-exchangers will be determined by the structure of the amorphous matrix. It was found that greater or lesser amounts of water absorbed by the PSMs were dependent on the method used to prepare the membranes, on the nature of the gegen-ion, on the concentration of the electrolyte surrounding the membranes, and on other factors. It is also known that ion-exchange groups in amorphous regions have an aggregation propensity leading to the formation of ionic cluster [1–3].