Freezing, melting and dynamics of supercooled water confined in porous glass

R. Neffati , P. Judeinstein (1, 2) , J. Rault (2)

1 LLB - UMR 12 - Laboratoire Léon Brillouin
2 LPS - Laboratoire de Physique des Solides

The freezing, melting and dynamics of supercooled water at different hydration of controlled porous glass (CPG) with mean pore sizes 10 nm, 30 nm, 50 nm and 70 nm are studied using differential scanning calorimetry (DSC) and deuteruim nuclear magnetic resonance (2 H-NMR). For saturated samples, the melting tempertaure follows the Gibbs-Thomson relation despite a clear linear decrease of the melting enthalpy when the transition is shifted due to confinement. For partially filled porous glasses the crystalization and melting temperatures as well as enthalpy are lower than for the saturated samples. 2 H-NMR confirms the existence of a non-crystallizable part of water adsorbed on the surface of pores. At room temperature, spin-lattice relaxation rate (1/T1) is proportional to the inverse of the mean pore size indicating that the relaxation is governed by a surface limited process. At low tempertaure relaxation rate follows the Vogel-Fulcher-Tammann (VFT) relation.

Mots clés: porous glass; hydration rate; freezing-melting; supercooled water; VFT equation

Domaines: Matériaux

R. Neffati, P. Judeinstein, J. Rault. Freezing, melting and dynamics of supercooled water confined in porous glass. Journal of Physics: Condensed Matter, 2020, 32 (46), pp.465101. ⟨10.1088/1361-648X/abaddd⟩. ⟨hal-02987552⟩