Study of ion solvation and ion association in polymer gel electrolyte with polyethylene oxide‐ co ‐polypropylene oxide as a plasticizer

Using a molal conductance method, ion solvation and ion association in polytriethylene glycol dimethacrylate (PTREGD)–LiClO 4 gel electrolytes with amorphous ethylene oxide‐ co ‐propylene oxide (EO‐ co ‐PO, M̄ n = 1750) as the plasticizer were investigated. It was found that the fraction of solute existing as single ions (α i ) and ion pairs (α p ) decreases, while that of triple ions (α t ) increases linearly with increasing salt concentration. The dependence of these fractions on molecular weight of plasticizer was also examined. It was shown that α i and α t increase and α p decreases with increasing molecular weight. The result of temperature dependence of these fractions was very interesting: when the temperature is lower than 55°C, α i increases while α p and α t decrease with increasing temperature; however, when the temperature is higher than 55°C, the reverse is true.