Molecular dynamics simulations for models of poly(Vinyl Alcohol) hydrogels and pure water have been carried out over a wide temperature range including the glass transition temperature to examine structure and dynamics of supercooled water in hydrogels. The temperature dependences of thermodynamic properties and rotational relaxation times at atmospheric pressure are investigated. Those properties depend seriously on mobility of polymer chains and network structures of hydrogen bonds. It is found that polymer chains affect significantly the dynamic properties and the fragile-strong character of water. Structure and dynamics of water in PVA hydrogels are characterized by two dynamical modes, the motion of main chains and that of side chains, whose time scales are different from motion of water.
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