COMP 21 |
| We carried out the first and thorough molecular modeling study of electro-wetting in a nanopore. Traditionally, electrowetting has been considered a relatively non-specific phenomenon defined in terms of a material's macroscopic properties. On a molecular level, where surface molecules represent a significant constituency, however, we show that the competition between spontaneous water molecule-surface orientations, and molecular dipole alignment in the field play a major role. Our simulations of wetting/dewetting equilibrium, along with ensuing analysis of hydrogen bond populations, demonstrate a surprisingly strong effect of field direction and polarity on nanopore-surface affinity for water. This new phenomenon is potentially relevant to surface manipulation in nanofluidics, as well as for basic understanding of field charge effects that modulate local hydrophilicity of engineered and biological interfaces. Figure: When electric field is applied in the direction perpendicular to the confining hydrophobic surfaces, the competition between field-induced alignment and orientational preference of interfacial water molecules relative to the surfaces results in asymmetric wettability of opposing surfaces (Janus interface).
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Recent Advances in Studies of Molecular Processes at Interfaces
8:30 AM-12:15 PM, Sunday, August 19, 2007 BCEC -- 156C, Oral
Division of Computers in Chemistry |
