Heterogeneous Microscopic Dynamics of Intruded Water in a Superhydrophobic Nanoconfinement: Neutron Scattering and Molecular Modeling

With their strong confining porosity and versatile surface 2 chemistry, Zeolitic Imidazolate Frameworks-including the 3 prototypical ZIF-8-display exceptional properties for vari-4 ous applications. In particular, forced intrusion of water 5 at high pressure (∼ 25 MPa) into ZIF-8 nanopores is in-6 terest energy storage. Such a system reveals also ideal to 7 study experimentally dynamics thermodynamics 8 in ultra-hydrophobic confinement. Here, we report on neu-9 tron scattering experiments probe molecular dynam-10 ics within under up 11 38 MPa. addition an overall confinement-induced 12 slowing down, provide evidence dynamical 13 heterogeneities with different underlying dynam-14 ics. Using complementary simulations, these het-15 erogeneities are found correspond microscopic 16 mechanisms inherent vicinal molecules located strongly 17 adsorbing sites (ligands) other nanoconfined 18 cavity center. These findings unveil complex micro-19 scopic dynamics, which results from combination sur-20 face residence times exchanges between sur-21