(188d) Electric-Field Assisted Assembly of Colloidal Dimers

Anisotropic colloids could possess anisotropic properties in geometry, chemical composition or surface functionality. As such, they can recognize each other and assemble via directional interactions, potentially making large numbers of crystalline arrays and meso-structures that isotropic spheres cannot form. A colloidal dimer is an ideal candidate for studying the impacts of specific anisotropic property on the assembly of anisotropic particles, because versatile synthetic methods are available to create and tune the anisotropic properties in geometric, chemical composition, surface functionality, and physical properties. In this talk, we will present our experimental and theoretical explorations on the assembly of colloidal dimers with anisotropies in both geometric size and surface charge. 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 colloidal dimers. All those patterns are strongly dependent on the frequency of electric fields, which makes this field-driven assembly strategy particularly attractive. Potential applications in the field of display will also be discussed.