|Publisher DOI:||10.1021/acs.jpcc.1c09801||Title:||Structure of water at hydrophilic and hydrophobic interfaces: raman spectroscopy of water confined in periodic mesoporous (organo)silicas||Language:||English||Authors:||Malfait, Benjamin
|Issue Date:||9-Feb-2022||Publisher:||Soc.||Source:||Journal of Physical Chemistry C 126 (7): 3520-3531 (2022)||Abstract (english):||
The 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.
|URI:||http://hdl.handle.net/11420/11783||ISSN:||1932-7455||Journal:||The journal of physical chemistry C||Institute:||Material- und Röntgenphysik M-2||Document Type:||Article||Project:||Veränderung der Eigenschaften mehrphasiger Flüssigkeiten durch geometrische Beschränkung in modernen mesoporösen Materialien||Funded by:||Deutsche Forschungsgemeinschaft (DFG)||More Funding information:||This work was conducted in the frame of the DFG-ANR collaborative project (Project NanoLiquids No. ANR-18-CE92-0011-01, DFG Grant No. Fr 1372/25-1-Project number 407319385, and DFG Grant No. Hu850/11-1-Project number 407319385), which is acknowledged.|
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