Hydrophobicity and geometry: Water at curved graphitic-like surfaces and within model pores in self-assembled monolayers

In this work we perform molecular dynamics simulations of water in contact with simple model hydrophobic surfaces and pores in order to test the role of local geometry on hydrophobicity. Specifically, we study different quantities like orientational ordering, density fluctuations and water residence times (autocorrelation functions) around graphene sheets, at the exterior of single-walled carbon nanotubes, at alkane-like self-assembled monolayers (SAMs) and at pores of different sizes carved in such SAMs. We show that in the case of the convex graphitic-like surfaces, the cuvature does not affect the local hydrophobicity. However, significant curvature dependence will be made evident for the concave surfaces of the pores carved in the SAMs. The geometrically induced dehydration that occurs as the pore size reaches the subnanometric regime might be operative in realistic settings like protein binding sites which require water remotion upon ligand binding. (C) 2013 Elsevier B.V. All rights reserved.