INFRARED AND X-RAY-DIFFRACTION STUDY OF THE HYDRATION PROCESS IN THE POLYMER ELECTROLYTE SYSTEM M(CF3SO3)2PEON FOR M = PB, ZN AND NI

Water uptake in the system M(CF3SO3)2PEOn, where M = Ni, Zn and Pb, and n = 6-24, has been investigated at room temperature using i.r. spectroscopy and X-ray diffraction. It has been found that the ion-pairing/clustering involving M2+ and CF3SO3- is highly affected by hydration, with water replacing CF3SO3- at the cation. At intermediate degrees of hydration, the CF3SO3- ions are hydrogen bonded to metal-ion coordinating water molecules. In conditions of water excess, features typical of CF3SO3- ions in aqueous solution are observed. The interaction between PEO and M2+ is also affected by hydration for M = Ni and Zn. The v(COC)a stretching band is shifted to higher wave numbers, indicating a weakening in the interaction between PEO and a hydrated cation. X-ray diffraction has shown that any crystalline component present in the anhydrous form is destroyed by water uptake.