Cross-flow migration is a term used to describe the migration of species perpendicular to the direction of flow. In polymer systems such effects are of interest in field-flow fractionation analytical techniques, including those proposed for next-generation DNA sequencing technologies.  Despite the obvious importance of polydispersity, studies usually simulate monodisperse chains or occasionally, a few different chain lengths. This work presents a comprehensive methodology for mapping various molecular weight distributions onto a finite number of lattice chains. The effects of polydispersity on melt dynamics, equilibrium properties, and under flow conditions are demonstrated.  In particular, the cross-flow migration of chains based on varying molecular weight in parabolic flow are discussed and contrasted to the case of shear flow where migration effects are absent. The new developments provide quantitative insight into the design of microfluidic devices for separating polymers based on molecular weight differences. 

Cross-flow migration effects in molecular scale simulations of polydisperse systems

248th National Meeting (2014)

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