Magnetic effects on the hydration of nanoscopic hydrophobic paraffin-like plates

The effect of an external static magnetic field on the hydration behavior of nanoscopic paraffin-like plates has been investigated using molecular dynamics simulation in an isothermal-isobaric ensemble. The "normal" and "hard-wall-like" hydrophobic potentials were both utilized to represent the water-solute interaction. Results demonstrate that water at ambient temperature was expelled from the confined region between two "normal" plates upon applying relatively low magnetic field, and attracted back under magnetic field beyond 0.7 T. The transition of magnetodesorption to magnetoadsorption is firstly achieved theoretically, which is in good agreement with experimental results reported by Ozeki et al. In contrast, water confined in the "hard-wall-like" plates is more sensitive to magnetic treatment. A liquid-to-vapor-like phase transition has been observed at the center of confined region at 0.7 T, similar to the behavior of confined water under the influence of an electric field. This indicates that aggregation of hydrophobic solutes can be induced by applying a magnetic field and could shed light on the mechanism of magnetic dewetting of hydrophobic surfaces.