Asymptotic analysis of tracer diffusivity in nonadsorbing polymer solutions

T.H. Fan, B. Xie, R. Tuinier

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20 Citations (Scopus)

Abstract

We present an asymptotic and scaling analysis of the long-time self-diffusivity of a Brownian spherical particle in dilute polymer solutions with nonadsorbing chains. The polymer depletion zone near the particle surface is described by a continuous polymer density profile. Hydrodynamics formulated by the modified Stokes equation with nonuniform viscosity is solved by a regular perturbation approximation using the Green function method. The asymptotes predict how polymer depletion alters the friction a spherical particle experiences during translational and rotational motion within a quiescent fluid. The analysis agrees very well with full numerical computation, which enables us to investigate the scaling law for the polymer-mediated retardation effect using a stretched exponential form that is commonly applied by experimentalists. The scaling exponents revealed are consistent with the nominal values from collected experiment observations.

Original languageEnglish
Article number051405
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume76
Issue number5
DOIs
Publication statusPublished - 16 Nov 2007
Externally publishedYes

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