(611b) Particle Pinning At Liquid-Liquid Interfaces

Razavi, S., The City College of New York, The City University of New York
Colosqui, C. E., Levich Institute of Physico-Chemical Hydrodynamics
Koplik, J., City College of the City University of New York
Kretzschmar, I., The City College of New York, The City University of New York

Physical and chemical heterogeneity are known to influence the interaction of colloidal particles with liquid interfaces. Such heterogeneities can produce undesirable or desirable effects depending on the specific application. Recent breakthroughs in particle synthesis have enabled the fabrication of particles with complex geometries and anisotropic surface properties. Hence, a fundamental understanding of the effects of surface features can be exploited in novel industrial processes. In this work, via molecular dynamics simulations we compute the free energy landscape for Brownian particles of different size and surface morphology that straddle the interface between two immiscible liquids. Our results demonstrate that nano-scale surface features can produce sufficiently large energy barriers that effectively "lock" the particle at specific angular orientations with respect to the liquid-liquid interface. These results provide new insights on the rotational dynamics of Brownian particles at interfaces. Our findings are relevant to various applications (e.g., reactive emulsions, peptide assembly) where is desirable that particles remain for long time periods in a specific angular orientation at the fluid interface.