title: Non-monotonic dependence of water reorientation dynamics on surface hydrophilicity: competing effects of the hydration structure and hydrogen-bond strength.
abstract: The reorientation dynamics of interfacial water molecules was recently shown to change non-monotonically next to surfaces of increasing hydrophilicity, with slower dynamics next to strongly hydrophobic (apolar) and very hydrophilic surfaces, and faster dynamics next to surfaces of intermediate hydrophilicities. Through a combination of molecular dynamics simulations and analytic modeling, we provide a molecular interpretation of this behavior. We show that this non-monotonic dependence arises from two competing effects induced by the increasing surface hydrophilicity: first a change in the hydration structure with an enhanced population of water OH bonds pointing toward the surface and second a strengthening of the water-surface interaction energy. The extended jump model, including the effects due to transition-state excluded volume and transition-state hydrogen-bond strength, provides a quasi-quantitative description of the non-monotonic changes in the water reorientation dynamics with surface hydrophilicity.
authors: Chemistry Department, Ecole Normale Supérieure, UMR ENS-CNRS-UPMC 8640, Paris, France. guillaume.stirnemann@ens.fr
authors: Guillaume
authors: G
authors: Stirnemann
authors: Santiago Romero-Vargas
authors: SR
authors: Castrillón
authors: James T
authors: JT
authors: Hynes
authors: Peter J
authors: PJ
authors: Rossky
authors: Pablo G
authors: PG
authors: Debenedetti
authors: Damien
authors: D
authors: Laage
mesh_terms: D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water