Structure of water in hydrogels investigated by neutron diffraction

Sekine, Yurina   ; Chi, S.*; Fernandez Baca, J.*; Fukazawa, Tomoko*; Fukazawa, Hiroshi

Hydrogels are unique polymer materials consisting of large amount of water in their three-dimensional networks. The structure of water is an important factor governing the chemical and physical properties of gel materials. To investigate structure and properties of water in poly-N,N,-dimethylacrylamide (PDMAA) gel, neutron diffraction and differential scanning calorimetry (DSC) curve of the high (90wt%) and low (55wt%) DO content gels were measured. The neutron diffraction patterns show that amorphous, cubic, and hexagonal ices exist in the low DO content gel at low temperature, whereas only hexagonal ice exists in the high DO content gel. The DSC result shows that the low DO content gel contains only intermediate and bound water. In contrast, high DO content gel contains free, intermediate, and bound water. Therefore the results indicate that amorphous and cubic ices are only formed when the hydrogels do not have the free water.