Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 56: Membranes and vesicles II (joint session BP, CPP)
CPP 56.6: Vortrag
Mittwoch, 18. März 2015, 16:30–16:45, H 1028
Attraction between hydrated hydrophilic surfaces — •Matej Kanduc1, Emanuel Schneck2, and Roland Netz1 — 1Department of Physics, Free University Berlin — 2Max Planck Institute of Colloids and Interfaces, Research Campus Golm
According to common knowledge, hydrophilic surfaces repel via hydration forces while hydrophobic surfaces attract, but mounting experimental evidence suggests that also hydrophilic surfaces can attract. Using all-atom molecular dynamics simulations at prescribed water chemical potential [1] we study the crossover from hydration repulsion to hydrophobic attraction between planar surfaces. We cover the complete spectrum from very hydrophobic surfaces (characterized by contact angles of 135°) to hydrophilic surfaces exhibiting complete wetting. Indeed, for a finite range of contact angles between 65° and 90°, we find a regime where hydrophilic surfaces attract at sub-nanometer separation and stably adhere without intervening water, in good agreement with experiments. Analysis of the total number of hydrogen bonds (HBs) formed by water and surface groups rationalizes this crossover between hydration repulsion and hydrophilic attraction in terms of a subtle balance [2]. Such solvent reorganization forces presumably underlie also other important phenomena, such as selective ion adsorption to interfaces as well as ion pair formation.
[1] M. Kanduc, A. Schlaich, E. Schneck, and R. Netz; Adv. Colloid Interface Sci. 208, 142 (2014).
[2] M. Kanduc, E. Schneck, and R. Netz; Chem. Phys. Lett. 610, 375-380 (2014)