End-group coordination has been studied using poly(propylene glycol) with a molecular weight of 3000 (PPG(3000)) terminated with hydroxy groups. On dissolution of different lithium salts LiX in PPG(3000) for X = PF6, BF~, CIO~, CF3SO3, I-, Br- and CI-, shifts of the OH stretching band were observed using Fourier transform infra-red spectroscopy. The size of the shift is dependent on the strength of the hydrogen bond formed between the OH group and the anion of the salt. A cation dependence of the OH stretching band was also found using KPF 6. There are two dominating coordination structures involving the OH groups present in the samples. One is a solvent-separated ion pair where the anion and cation are separated by an OH end-group, and the other is an OH group coordinated both to the cation of the salt and to an ether oxygen from the polymer.
Посилання на статтю:
Coordination of OH end-groups in the polymer electrolyte system LiX-PPG for X=PF , BF4, C104, CF3S03, I-, Br- and CI / Annika Bernson and Jan Lindgren // Polymer. – 1994. – Vol 35. – P. 4848-4851.