(147b) Computational Investigation of Multipolar Colloidal Particle

Colloids with anisotropic charge distributions hold promise for creating a number of useful new materials including optic materials with novel symmetries, materials for information storage, and dampers for controlling vibrations in structures. Experimentally manipulating properties of anisotropic particles in a controlled fashion can sometimes be difficult and is time consuming. The search for novel anisotropic colloidal materials can be enhanced and even guided by simulations of colloidal system assembly. We report the results of two projects. In the first we use discontinuous molecular dynamics (DMD) simulation to investigate how the internal charge separation of anisotropic, dipolar colloidal rods with 4:1 aspect ratio affects their phase behavior. The differences between the head-tail and side-side ordering displayed in these simulations could be exploited to design gels whose properties (especially those related to percolation: viscosity, conductivity, etc.) are responsive to external stimuli. In the second project we perform quasi-2D Monte Carlo simulations of systems of colloidal spheres with off-center, extended dipoles. These colloidal spheres are found to aggregate into cyclical structures whose interior angle is equal to the angle between the charges on a single dipolar sphere.