(145a) New Directions for Entropic Forces in Hard Particle Fluids

Entropic forces in hard particle fluids can order particles into organized assemblies.  Liquid crystal, plastic (rotator) crystal,  quasicrystal, and both simple and complex crystal phases have all been reported for hard shapes that interact solely through excluded volume interactions. We present the results of extensive Monte Carlo simulations of nearly 200 different fluids of hard shapes and their thermodynamic assemblies.  We show how particle shape and local measures of order in the dense fluid can be used to predict the category of assembly.  We discuss the concept of entropic "bonding" and demonstrate the directional nature of entropic forces in fluids of non-spherical hard particles.  We show how these concepts lead naturally to predictive design rules for colloidal and other matter.

In collaboration with: K. Ahmed, L. Boehling, E. Chen, P. Damasceno, M. Engel, T. Grubb, A. Haji Akbari, E. Irrgang, A.S. Keys, D. Klotsa, J.A. Millan, R. Newman, S. Nola, D. Ortiz, B. Schultz, R. Smith, & G. van Anders

This work supported by the U.S. Department of Defense Army Research Office, Air Force Office of Scientific Research, and Assistant Secretary of Defense for Research and Engineering.