Effects of polymer chains on structure and dynamics of supercooled water in poly(vinyl alcohol)

Molecular-dynamics simulations for poly(vinyl alcohol) hydrogels have been carried out in a wide temperature range 150-400 K to examine effects of polymer chains on structure and dynamics of supercooled water in hydrogels. A fragile-strong character of water under perturbations of polymer chains is examined. Polymer chains affect the fragile-strong character of water, which is manifested in temperature dependences of potential energy, translational diffusion coefficient, and orientational relaxation time. Water coexisting with polymer has a rather stronger character in the strong-fragile classification than that in pure water. Structure and dynamics of water in hydrogels are significantly altered by the slow dynamics of polymer chains, as well as the structure and dynamics of hydrogen-bond networks. [S1063-651X(99)04405-0].