Short-time dynamics and high-frequency rheology of core-shell suspensions with thin-shells

TL;DR

This paper investigates the short-time dynamics and high-frequency rheology of suspensions with core-shell particles, deriving effective parameters and validating the annulus approximation through virial expansion analysis.

Contribution

It introduces a theoretical framework for core-shell suspensions with thin shells, deriving effective radii and validating the annulus approximation against other models.

Findings

Effective radius defined by scattering coefficients

Annulus approximation accurately models virial coefficients

Effective hard sphere model less precise

Abstract

Short-time dynamics and high-frequency rheology for suspensions of non-overlapping core-shell particles with thin shells were analyzed. In the thin-shell limit, the single-particle scattering coefficients were derived and shown to define a unique effective radius. This result was used to justify theoretically (in the thin-shell limit) the accuracy of the annulus approximation with the inner radius equal to the effective hydrodynamic radius of the core-shell particle. The two-particle virial expansion of the translational & rotational self-diffusion, sedimentation and viscosity was performed. The virial coefficients were evaluated and shown to be accurately approximated by the effective annulus model, in contrast to the imprecise effective hard sphere model.