Phase transition properties of poly(ethylene oxide) in aqueous solutions of sodium chloride

The phase transition properties of poly(ethylene oxide) (PEO), in aqueous s olution, have been examined by differential scanning calorimetry (DSC) in t he presence of NaCl (0-2 M). DSC studies show, for the first time, that the PEO phase transitions have an unusual line shape, the exact nature of whic h is dependent on NaCl concentration. The T-m (temperature of maximum appar ent excess heat capacity) decreases with increasing [NaCl]. FT-IR experimen ts reveal that changes occur in the conformation of the C-O-C backbone of P EG, in the presence of 2 M NaCl, at the same temperature as the discontinui ty in the apparent excess heat capacity function observed by DSC.