Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Wetting, Superamphiophobicity, Micro- and Nanofluidics I

CPP 18.2: Talk

Tuesday, April 1, 2014, 09:45–10:00, ZEU 222

Understanding the effect of temperature on hydrophobic wetting through molecular dynamics simulations — •Frédéric Leroy — Technische Universität Darmstadt, Darmstadt, Germany

Hydrophobic surfaces usually yield water contact angles which weakly depend on temperature. To explain this observation, we address the thermodynamics of formation of interfaces between rigid non-polar solid surfaces and water. The work of adhesion of water can be separated in its enthalpy and entropy contributions per unit area W=ΔH/A-TΔS/A.[1] While the enthalpy relates to the energy loss upon separating the liquid and the solid phases, the entropy change characterizes the entropy gain of water upon separation. Inspired by the analogy between the solvation of particles in water and the formation of solid-liquid contacts, a clear microscopic interpretation of both contributions in terms of intermolecular interaction potentials is given.[2] We illustrate how the determination of ΔH and ΔS by means of molecular simulations of water on rigid non-polar surfaces explains why the work of adhesion has a greater temperature dependence on hydrophobic than on hydrophilic surfaces.[3,4]

[1] Taherian, F.; Marcon, V.; van der Vegt, N.F.A and Leroy, F. "What is the Contact Angle of Water on Graphene?" Langmuir 29, 1457-1465 (2013) [2] Taherian, F.; Leroy, F and van der Vegt, N.F.A. "Interfacial Entropy of Water on Rigid Hydrophobic Surfaces" Langmuir 29, 9807-9813 (2013) [3] Kumar, V. and Errington, J.R. "Wetting Behavior of Water near Nonpolar Surfaces", J. Phys. Chem. C 117, 23017-23026 (2013) [4] Leroy, F., in preparation