Nanoparticle self assembly at liquid-liquid interfaces is an important process in forming nanostructured devices and Pickering emulsions.  Ionic liquids, with their unique composition, present a new kind of liquid-liquid interface which is not yet well understood.  We have studied the self-assembly of hydrophobic nanoparticles at ionic liquid (IL)-water and IL-oil (hexane) interfaces using molecular dynamics (MD) simulations.   For the 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6])/water system, the nanoparticles rapidly approached the IL-water interface and equilibrated more into the IL phase although they were initially in the water phase.  In contrast, when the nanoparticles were dispersed in the hexane phase, they slowly approached the IL-hexane interface but remained primarily in the hexane phase. Particle-IL interactions depended significantly on particle charge and interface type (water or oil). Potential of mean force (PMF) calculations supported the observations from the equilibrium studies and correlated reasonably well with continuum models for nanoparticle desorption from the liquid-liquid interface.

Molecular dynamics simulations of nanoparticle self assembly at ionic liquid-based interfaces

243rd National Meeting (2012)

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