DYNAMIC PROPERTIES OF WATER IN POROUS VYCOR GLASS STUDIED BY DIELECTRIC TECHNIQUES

The structure and dynamic properties of water in porous Vycor glass of 40 angstrom mean pore diameter, as well as their changes with temperature, were studied by dielectric relaxation spectroscopy and dc conductivity measurements. The mobility of water molecules in the pores was reduced compared with that of bulk water by a factor which decreased with increasing water content. A significant fraction of water in the first monolayer is transformed to a glassy state at about 170 K. The formation of water clusters around primary hydration sites started at about 0.02 g(H2O)/g (dry sample) where a transition to long-range connectivity among water molecules was observed.