Summary: Spherical colloids with isotropic properties have been used as building blocks to assemble a variety of 2D and 3D structures in past, such as FCC, HCP, and BCT crystals. Anisotropic particles are, however, more faithful mimics of molecules and atoms because of the anisotropic interactions. Current synthetic methods are versatile and accurate enough to create and tune the anisotropic properties in geometry, chemical composition, surface functionality, and physical properties. In the first part of this talk, we will present our experimental and theoretical explorations on the assembly of colloidal particles with anisotropic interactions. Surprisingly rich patterns and crystalline arrays have been observed under the influence of AC electric fields. Our modeling demonstrates that the competition and balance between the double layer interaction, the induced dipole-dipole interaction, the electro-hydrodynamic flow, and the image forces determine different phases and packing paths between anisotropic particles. All those patterns are strongly dependent on the frequency of electric fields, which makes this field-driven assembly strategy particularly attractive. In the second part of this talk, we will present two energy-related applications of anisotropic particles: for both conventional petroleum industry and renewable energy industry such as thin-film solar cells.
Dr. Ning Wu joins CSM as Assistant Professor of Chemical Engineering in fall 2010. He holds a B. Eng. in Chemical Engineering from the National University of Singapore, and a Ph. D in Chemical Engineering from Princeton University, working with Prof. William Russel. Before joining CSM he has worked at Harvard University as a postdoctoral researcher (with Prof. Joanna Aizenberg) for two years. His major research interest lies in finding simple and elegant ways to control the structures of materials at different length scales precisely, which are important for the development of more efficient photovoltaics, photonic crystals, multi-functional and environmentally adaptive nanomotors, as well as biomedical diagnostic/therapeutic systems. His recent work on the assembly of colloidal dimers was featured on the cover of Oct. issue of Advanced Functional Materials.
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