(264i) Molecular Insights into the Electrowetting Behavior of Aqueous Ionic Liquid

Electro-wetting is the modulation in the wettability of a surface prompted by an external voltage [1, 2] across the solid/liquid interface. Ionic liquids (ILs) which have unique physicochemical properties,[3] gain industrial significance, due to its development as a promising alternative medium for electrowetting. This phenomenon is exploited in various applications such as variable fluid lens systems, electrowetting displays, programmable optical filters, paint drying, micro motors, electronic microreactors, liquid optics, or lab-on-a-chip devices.[4-7]

Molecular dynamics simulations were applied to study the wetting behavior of nanoscale aqueous hydrophilic and hydrophobic Imidazolium-based ionic liquid (IL) droplets on a solid graphite substrate subjected to the perpendicular electric field. Imminent transformation in the droplet configuration was observed at E = 0.08 V/Å both for hydrophobic ILs [EMIM][NTF₂] and SPC/E water droplets. However, for hydrophilic, [EMIM][BF₄], the droplet was completely stretched to be column-shaped under the electric field E = 0.09 V/Å for lower weight percentages of ILs and E > 0.1 V/Å at a higher weight percentage of ILs (> 30 wt%), because of the hydrophilic nature of [EMIM][BF₄]. We explore the impact of electric-field through various parameters such as mass density distribution, contact angle, orientation, and hydrogen bonds.

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