Factors governing solvate stability in polyethers complexed with alkali thiocyanates

Solubilities of LiSCN, NaSCN, KSCN, and CsSCN in atactic poly(methyl glycidyl ether) have been determined by means of glass transition temperature (T g ) and calorimetric measurements. For all salts except LiSCN, step decreases in solubility were observed with increasing temperature over the range 25-200°C. The data for NaSCN and KSCN indicate that solvates of well-defined compositions are stable over a range of temperatures on either side of the transitions. A comparison of these compositions with those reported for poly(ethylene oxide) reveals that several factors govern solvate stability in polyethers. Among these factors are configurational entropy, cation-oxygen binding energy, ion-ion Coulombic interactions, and presumably space-filling forces related to the size of the anion