posite materials, and many other technologies. Silica gels Properties of water adsorbed in porous Vycor glass and Vycor and controlled pore glasses are available in well-defined bulk glass treated with hexamethyldisilazane (HMDS) have been studcomposition and in a range of specific surface areas and ied by measuring NMR as a function of water content and temperporosities, and the surface properties can be altered by silane ature and observing penetration of water into the pores. Some of treatments. Therefore, many studies on the interfacial phethe observed properties are compared with those of methanol and nomena have been carried out with silica gel and porous ethanol. The NMR linewidth of water in original glass pores is glass/water systems. Most of the early work on the properproportional to the fraction of water in a surface monolayer on the ties of water in the vicinity of a surface or interface have glass. The melting point depression of the pore water is inversely
proportional to the pore radius, and ice water interfacial tension been summarized in reviews (1, 2). During the past 20 is evaluated as 27.5 mN/m. When treated glass was immersed in years, various properties of water such as viscosity, density, water, liquid water could not penetrate the glass sample, which heat capacity, freezing, and mobility of molecules have been had more than 0.4/nm 2 trimethylsilyl group substituted for surface investigated in a variety of substances (3-10). Among those hydroxyls; however, the alcohols could still easily penetrate the interested in the behavior of water near surfaces, the range fully treated glass, which had 1.3/nm 2 trimethylsilyl groups. Water and extent of vicinal modification are current topics of readsorbed in weakly treated glass shows broadening of the NMR search. The extent and range of the effective perturbations line; contrastingly, the alcoholic hydroxyls show narrowing of the appear to be different for different properties and dependent lines. The freezing and melting point of pore water rise with suron the physical quantity examined and experimental condiface treatments. These phenomena can be explained in terms of tions. It has been reported that the vicinal water structuring structure forming of adsorbed liquid on the surfaces and the interaction between the molecules in the structured layer and the subse-apparently extends over long distances (Γ5 nm or more) quent layer.