Effects of hydrophilic groups of polymer on change in hydrogen-bonding structure of water in hydrogels during dehydration

Sugiyama, Hitoshi*; Kato, Kenichi*; Sekine, Naoko*; Sekine, Yurina   ; Watanabe, Tomoaki*; Fukazawa, Tomoko*

To investigate the effects of polymer hydrophilicity on structures of water in hydrogels, differential scanning calorimetry and X-ray diffraction measurements were performed. The results show that the amount of intermediate water in polyacrylamide (PAA) hydrogel is about 12% smaller than that in poly--dimethylacrylamide (PDMAA) hydrogel. Furthermore, it was found that the bound water in PAA hydrogel primarily exists around the surface of the polymer bundles, whereas that in PDMAA hydrogel acts as a crosslinker factor for dehydration and water absorption in hydrogels.