261266 Energy and Diffusivity Landscapes From Smoluchowski Analyses and Shape Matching of Colloidal Crystallization Dynamics

Monday, October 29, 2012
Hall B (Convention Center )
Daniel J. Beltran-Villegas and Michael A. Bevan, Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD

Understanding concentrated colloidal dynamics in the presence of different pairwsie interactions and external fields provides a basis to predict the temporal evolution of colloidal microstructures in colloidal crystallization.  However, a theory of concentrated colloidal dynamics does not yet exist that rigorously includes both statistical mechanical (free energy changes) and fluid mechanical (hydrodynamic interactions) contributions associated with changing microscopic configurations.  In this talk, we report the development of an order-parameter based Smoluchowski Equation (SE) model that accurately captures the dynamic evolution of initially disordered colloidal fluid configurations into colloidal crystals in the presence of either tunable depletion or electric field induced interactions.  We first identify appropriate order parameters to monitor colloidal crystallization. These order parameters are computed by means of novel shape matching techniques.  With this foundation, we apply the SE analysis to extract free energy and “diffusivity landscapes” from the BD and SD simulations to understand the role of multi-body hydrodynamic interactions in colloidal crystallization dynamics.  Finally, we demonstrate the use of these landscapes in the SE model to estimate key dynamic information, such as mean passage times between microscopic states and crystallization success ratios.  These results provide a basis to control colloidal crystal assembly processes via open- and closed- loop control to produce perfect single colloidal crystals.

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