Nanodroplets Behavior on Functionalized Nanopores

Ygor Morais Jaques and Douglas Soares Galvão

University of Campinas/Rice University and University of Campinas

The engineering of new materials with micro/nanostexturized surface has important applications on the realm fluid dynamics, more specifically on the wetting behavior of such patterned materials 1. It could lead to the achievement of extraordinary properties, like fast detachments 2, superhydrophilicity and superhydrophobicity 3,4. Some of these properties can be very useful to applications concerning anti-icing, anti-fogging and self-cleaning materials 5,6. To understand, at atomic level, how a liquid like water behaves when into contact with such materials, we investigated through molecular dynamics the permeation behavior of water nanodroplets on carbon nanotubes forests. Different tube arrangements were considered, where we varied tube diameters, the spacing between them, as well as, distinct functional groups (hydrogen and hydroxyl groups) to achieve different degrees of hydrophilic and/or hydrophobic behaviors. The results show that simple functional groups can tune the wetting behavior of nanotube forests, at least in terms of droplet spreading and permeation, and this happens in spite of the tube internal surface hydrophobicity. For hydrogen functionalization, the droplet does not exhibit significant spreading and increasing the pore size the permeation increases. For the hydroxyl functionalization, the droplets are widely spread on forest surface and even for 20 Å of spacing the droplet permeation is not expressive.

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