Effect of silica and water content on the glass transition of poly(ethylene glycol) monomethylether–silica gel–lithium perchlorate ormolytes

The effect of silica and water content on the glass transition temperature, T g, of MPEG2000–silica–LiClO 4 ormolytes was assessed by differential scanning calorimetry (DSC). The sol–gel synthesized ormolytes consisted of various amounts of poly(ethylene glycol) monomethylether (M.W. = 2000 g/mol; i.e., MPEG2000) tethered to silica gel through the hydroxyl terminus via a urethane linkage. DSC features corresponding to physisorbed and hydrogen-bonded water, as well as the glass transition of the polyether, were identified. Both silica and LiClO 4 raise the T g and suppress crystallization of the polyether component. Water plasticizes the polyether and stoichiometrically solvates and sequesters Li +, thereby, lowering T g.