Energy and Diffusivity Landscapes From a Smoluchowski Analysis of Colloidal Crystallization Dynamics

Wednesday, October 19, 2011: 8:30 AM
102 B (Minneapolis Convention Center)
Daniel J. Beltran-Villegas, Jaime J. Juárez, Tara D. Iracki 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 (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.  We then show that free energy landscapes from Monte Carlo (MC) umbrella sampling produce the same free energy landscapes as our SE analysis of Brownian Dynamic (BD) and Stokesian Dynamic (SD) simulations.  With this foundation, we apply the SE analysis to extract “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 capture first passage times between different microscopic states.  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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See more of this Session: Computational Studies of Self-Assembly II
See more of this Group/Topical: Engineering Sciences and Fundamentals