(717c) Directing Translational and Orientational Order of Rectangular Particles on a Surface

Many recent advances have shown that the tunability of nanoparticle interactions can lead to a large number of thermodynamically accessible structures.  The role of an external field in the assembly of particulate systems, however, is still incompletely understood.  The use of larger scale patterned substrates to drive smaller scale directed self-assembly of particle monolayers can potentially expand the set of achievable lattices, and could be used in nanopatterning processes or in the manufacture of functional materials.  In this presentation, grand canonical Monte Carlo (GCMC) simulations are used to evaluate the suitability of graphoepitaxial assembly for particle monolayers.  Our previous work has shown that use of topologically or chemically patterned substrates can sufficiently organize hard-sphere particles, but many motivating applications can benefit from the use of anisotropic particle shapes (e.g. rectangular particles for bit-patterned magnetic media).  Here, we describe our most recent GCMC results that focus on structures that rectangular particles can form in the presence of sparse enthalpic barriers.  We examine systems of varying chemical potential, template geometry, particle aspect ratio, and barrier height.  Templates are evaluated by their ability to induce orientational and translational order, while maximizing pattern multiplication effects.