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Search This Site | People | Departments | Penn State
Lenore L. Dai
Department of Chemical Engineering
Texas Tech University
Lubbock, TX 79409
Thursday, March 6, 2008
102 Chemistry Building
10:00 a.m. - 11:00 a.m.
Abstract
Emulsions are ubiquitous in natural and industrial processes. Conventional emulsions use organic surfactants or polymers as stabilizers. Although solid particle stabilized emulsions (Pickering emulsions) are often encountered in crude oil recovery, oil separation, cosmetic preparation, and wastewater treatment, the phenomenon is poorly understood.
Here we explore the fundamentals and applications of Pickering emulsions. Using laser scanning confocal microscopy and environmental transmission electron microscopy, we have studied the self-assembly of polystyrene microparticles and alkanethiol-capped silver nanoparticles in Pickering emulsions. In contrast to microparticles forming a monolayer, the alkanethiol-capped silver nanoparticles of 1-5 nm formed multilayers and packed randomly at the emulsion interfaces. We have also used molecular dynamics (MD) simulations to understand the self-assembly of nanoparticles at oil-water interfaces. The simulation has clearly shown the progress of cluster formation, migration, and final equilibrium of both single particles and clusters at the interfaces. In addition, we have pioneered the work of using Pickering emulsions as a new and unique experimental model system to investigate the dynamics of microparticles at liquid-liquid interfaces and to develop interfacial microrheology. Finally, we have used Pickering emulsions as a novel template to synthesize composite-latexes through a one-step emulsion polymerization.