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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 43: Wetting, Fluidics and Liquids at Interfaces and Surfaces (joint session CPP/DY)
CPP 43.7: Talk
Thursday, March 21, 2024, 17:00–17:15, H 0107
The Structure of Water Under Confinement in Periodic Mesoporous Organosilicas Investigated by X-Ray Scattering — •Niels Christian Gießelmann1, Philip Lenz2,3, Sophia-Marie Meinert2, Tamás Simon2, Wonhyuk Jo1,4, Nele Naomi Striker1, Michael Fröba2,3, and Felix Lehmkühler1,3 — 1Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — 2University of Hamburg, Institute of Inorganic and Applied Chemistry, Hamburg, Germany — 3The Hamburg Centre for Ultrafast Imaging, Hamburg, Germany — 4European XFEL, Schenefeld, Germany
The effect of pore wall chemistry and pore diameter on the structure of confined water was studied by X-ray scattering on water confined in periodic mesoporous organosilicas (PMOs). A shift in the first structure factor peak at q≈1.8 Å−1 reveals a variation in the density of the confined water in dependence of hydrophilicity and pore size. Smaller and more hydrophilic pores induce a lower density in the water. In contrast to bulk water, the pair distribution functions (PDFs) of confined water show a splitting of the second-neighbour peak into either two, in the case of smaller and more hydrophilic pores, or three separate peaks, in larger and more hydrophobic pores. From the running coordination number we conclude that smaller and more hydrophilic confinement leads to a stronger developed tetrahedral network in confined water, while confinement in larger and hydrophobic pores give tetrahedral arrangements that are bulk-like or even less pronounced than in bulk water.
Keywords: Water; X-ray scattering; Confinement; Porous Materials; Hydrogen bonding