INTERACTION OF POLY(ETHYLENE OXIDE) WITH SOLVENTS .4. INTERACTION OF WATER WITH POLY(ETHYLENE OXIDE) CROSS-LINKED HYDROGELS

The nature of the association of water with poly(ethylene oxide) has been studied using crosslinked gels containing 78.4 to 92.5% by weight of poly(ethylene oxide). The interaction of the hydrogel with water is generally attributed to hydrogen bonding between the hydrogen of the water molecule and the ether oxygen of the network. The ether oxygen atom takes on one molecule of water to form a monohydrate and then complexes a further two molecules of water to form a stable trihydrate. Evidence for the formation of these hydrates has been obtained by measuring the heat of partial swelling, the specific heat of hydration and the crystalline melting endotherms. Differential scanning calorimetry showed that trihydrate formation depends quantitatively upon the weight fraction of poly(ethylene oxide) in the gel. A helix model for the stable trihydrate is tentatively proposed. © 1990.