275305 Programmed Assembly of Janus, Patchy and Mixed Strongly Interacting Particles by Electric Fields

Wednesday, October 31, 2012: 8:30 AM
406 (Convention Center )
Sumit Gangwal1, Bhuvnesh Bharti2, Gerhard H. Findenegg2 and Orlin D. Velev1, (1)Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, (2)Department of Chemistry, Technical University Berlin, D 10623 Berlin, Germany

We will discuss how directional polarization interactions induced by external AC fields can be used to assemble complex particles or particle mixtures into unusual lattices of programmed structure and symmetry. Metallodielectric Janus particles could be driven into new types of staggered chains and anisotropic crystals. Patchy metallodielectric particles in AC fields form networks and crystals of unusual symmetry by quadrupolar and hexapolar interactions. The fundamental interpretation of these results is based on calculations of the electrostatic interactions and simulations of the molecular dynamics of the particles. We will also report a new class of permanently bound structures field-assembled from binary mixtures of microspheres of opposite charge with strongly attractive interactions. We demonstrate that the assembly process critically depends on the size ratio and the number ratio of the two types of particles, and derive assembly rules for the structures resulting from the process. The statistical model that we developed for this new type of irreversible directed assembly predicts a chain length distribution that was found to be in excellent agreement with the experimental data. These findings could form a basis for tailored assembly of supracolloidal structures from complex binding units.

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