Elasto-hydrodynamic Network Analysis of Colloidal Gels

Abstract eng:
We investigate the spectrum of relaxation times and relaxation normal modes in percolated colloidal networks. The relaxation spectrum is intimately tied to the linear viscoelasticity of such networks, and the spatial heterogeneity of the normal modes describes how susceptible structures of different length scales are to deformation. We show that these quantities are highly sensitive to hydrodynamic forces exerted on the network. Models for the hydrodynamic forces that neglect hydrodynamic interactions show significant departures from those that include them in dilute networks. In dense networks, hydrodynamic screening reduces the strength of the interactions, and the predicted relaxation spectra coincide regardless of hydrodynamic model. We show that modes of energy dissipation in the network are fundamentally altered by the presence of long-ranged hydrodynamic interactions. Analogous to the Zimm model in polymer dynamics, models describing network viscoelasticity must incorporate these effects of hydrodynamic coupling across the network to accurately predict the experimental response.

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