Cooling and heating curves of water confined in partially filled Vycor porous glass were measured for both adsorption and desorption processes. One endothermic and two exothermic peaks were observed for almost all cases. The peak temperature and the enthalpy of the exothermic peak located below 232 K increased initially and then decreased with further increases in the filling factor. These abnormal changes were analyzed based on the liquid−solid transition of nanoconfined water using a core/shell model, and the initial adsorption process of water in this typical mesoporous material with disordered pores is discussed. In addition, an interesting observation is that different peak temperatures for the endothermic peak and an almost constant peak temperature for the exothermic peak were observed at the same filling factor obtained under different sample preparation conditions, that is, adsorption and desorption processes. To compare with the liquid−solid transition temperatures of confined water in fully filled silica-based mesopores of different pore radius, a parameter of the ratio of pore inner surface area to confined liquid volume is proposed in this paper. Referring to this parameter, the core part of confined water in silica-based nanopores has the same liquid−solid transition temperatures. This suggestion is valid for the freezing process of water confined in either fully filled ordered or fully or partially filled disordered pores. For the melting process, different linear changes of melting temperature with the ratio of pore inner surface area to liquid volume were observed for water in disordered and ordered pores.

The vibrational dynamics of water within Vycor 7930 under different hydration levels and adsorption and desorption processes has been investigated by Raman measurements. Based on the successfully depressing the background fluorescence of Vycor, a new Gaussian peaking at 3590 cm−1 has been observed in the Raman spectrum of confined water. By comparison with the published Raman data of water within fully filled silica-based pores or reverse micelles, it is confirmed that a small confinement size may conceal the characteristic effect of hydrophilic interface. In addition, a density hysteresis observed within a filling fraction (ϕ) range of 0.25 < ϕ < 0.5 indicates that the cavitation model should be previously considered to explain the adsorption hysteresis of the water/Vycor system.