Colloidal Particles at Liquid-Fluid Interfaces, Thin Films, and Membranes
Our research work is producing new models to better understand the behavior of colloidal particles and complex fluids at "soft" interfaces and thin films. Analytical models developed as part of this research can account for experimental observations in recent studies by our group at Stony Brook U. and collaborators' groups (Prof. H.A. Stone at Princeton U., Prof. V.N. Manoharan at Harvard U.). Metastability induced by physical and/or chemical heterogeneities can produce regime crossovers from deterministic dynamics to thermally activated kinetics, which has dramatic effects on the time scales to reach thermodynamic equilibrium states. Among many other applications, the studied effects can be employed to control the adsorption of nanoparticles at lipid bilayers that form the membrane of different cells or to stabilize new colloidal materials, such as water-in-water emulsions. This research area has opened exciting directions that we are currently exploring with collaborators.
Nanostructured Surfaces for Separation Processes and Wettability Control
Nano/Microfluidic devices can be employed for applications such as energy conversion/storage and water treatment among many others. In nano/microscale systems, Brownian motion, the nanoscale interfacial structure, and surface forces produce a variety of wetting and transport phenomena that enable exciting technical applications. Advances in nanofabrication allow us to engineer the nanoscale structure of surfaces of nano/microfluidic devices in order to control the interplay between thermal motion and interfacial forces, and thus enhance the selective transport and separation of different fluids, solutes, and colloidal materials. At user facilities in the Center for Functional Nanomaterials of Brookhaven National Laboratory (BNL), our group is currently designing and fabricating slit nanochannels with superhydrophobic nanostructured surfaces having ordered arrays of conical nanopillars (~10 to 100 nm). When using electrolyte solutions these prototype nanofluidic devices can convert mechanical pressure into electric current with unprecedentedly high efficiencies owing to the selective transport of different ions. This project receives support from the Office of Naval Research. In other project supported by the National Science Foundation, we are designing porous materials consisting of capillary arrays with nano/microstructured surfaces. These nanoporous materials can efficiently separate water and organic liquids insoluble in water (e.g, oils) through selective wetting.