(82d) Colloidal Particles with Directional Interactions

A method is described for synthesizing a versatile new class of nearly spherical colloidal particles that interact with well-defined non-spherical symmetries. These particles are typically several hundreds of nanometers in diameter and have attractive interaction potentials with twofold, threefold, fourfold, or higher symmetries. For example, a colloidal suspension of particles with attractive potentials possessing twofold symmetry forms chains while a suspension of particles possessing fourfold symmetry forms aggregates with local tetrahedral symmetry. Thus, these particles have a well-defined "valence" analogous to atoms: the particles with twofold and fourfold attractive interactive potentials are analogous to sulfur and carbon, respectively, for example. Exotic higher symmetry particles are also available, particles with 7-fold or 12-fold icosahedral symmetries can be made.