Electromagnetically coupled wetting and transport behavior of alkylimidazolium ionic liquids

Alkylimidazolium ionic liquids exhibit unique physicochemical properties and responsiveness to external physical fields. Here, the effects of electric, magnetic, and combined electromagnetic fields on their wettability and transport behavior were systematically investigated. Electric and magnetic fields reduced the contact angle, while mutually perpendicular combined fields induced enhanced wetting, contact-angle hysteresis, and directional migration. The migration velocity of [MPIm]Br increased from 0.00370 to 0.00690 mm/s as the voltage increased from 5 to 20 V and reached 0.01587 mm/s at 25 V. Increasing the temperature from 20 to 40 °C increased the velocity from 0.00200 to 0.02326 mm/s, whereas increasing the water content from 0.74389% to 0.79734% reduced it from 0.02325 to 0.00051 mm/s. The migration velocity also increased with magnetic-field intensity, and ionic liquid solutions showed enhanced transport associated with reduced viscosity. Field-responsive wetting was also observed on hydrophobic PTFE. Repeated testing and ¹H NMR analysis revealed no detectable chemical-structure changes. These findings support a coupled interfacial-transport mechanism and provide a strategy for active regulation of ionic-liquid-based transport.