Malfait, BenjaminBenjaminMalfaitMoreác, AlainAlainMoreácJani, AichaAichaJaniLefort, RonanRonanLefortHuber, PatrickPatrickHuberFröba, MichaelMichaelFröbaMorineau, DenisDenisMorineau2022-02-282022-02-282022-02-09Journal of Physical Chemistry C 126 (7): 3520-3531 (2022)http://hdl.handle.net/11420/11783The temperature dependence of the structure of water confined in hydrophilic mesostructured porous silica (MCM-41) and hydrophobic benzene-bridged periodic mesoporous organosilicas (PMOs) is studied by Raman vibrational spectroscopy. For capillary filled pores (75% relative humidity, RH), the OH stretching region is dominated by the contribution from liquid water situated in the core part of the pore. It adopts a bulklike structure that is modestly disrupted by confinement and surface hydrophobicity. For partially filled pores (33% RH), the structure of the nonfreezable adsorbed film radically differs from that found in capillary filled pores. A first remarkable feature is the absence of the Raman spectral fingerprint of low-density amorphous ice, even at a low temperature (-120 °C). Second, additional bands reveal water hydroxyl groups pointing toward the different water/solid and water/vapor interfaces. For MCM-41, they correspond to water molecules acting as weak H-bond donors with silica and dangling hydroxyl groups oriented toward the empty center of the pore. For benzene-bridged PMO, we found an additional type of dangling hydroxyl groups, which we attribute to water at the hydrophobic solid interface.en1932-7455202273520 - 35313520 - 3531Soc.PhysikJournal Article10.1021/acs.jpcc.1c09801Other