Analytical Analysis of the Conformational and Rheological Properties of Flexible Active Polar Linear Polymers under Shear Flow

TL;DR

This paper provides an analytical study of how active polar linear polymers behave under shear flow, revealing activity-driven conformational changes and shear-thinning effects that differ from passive polymers.

Contribution

We develop an analytical model for active polar linear polymers under shear flow, highlighting activity-induced conformational and rheological modifications.

Findings

Enhanced transverse shrinkage with shear rate, exponent -4/3

Amplified shear-thinning behavior linked to activity

Large activity limit matches passive polymer behavior

Abstract

The conformational and rheological properties of active polar linear polymers (APLPs) under linear shear flow are studied analytically. We describe a discrete APLP as an inextensible flexible Gaussian bead-spring chain supplemented by active forces along the bonds. The linear, non-Hermitian equations of motion are solved by an eigenfunction expansion in terms of a biorthogonal basis set. The model reveals an intimate coupling between activity and shear flow, which implies activity-enhanced polymer conformational and rheological properties. Compared to a passive polymer, we find a significantly enhanced shrinkage transverse to the flow direction with increasing shear rate, with a power-law exponent $-4/3$, compared to the passive values of $-2/3$. This conformational change is tightly linked with a strongly amplified shear-thinning behavior, where the shear viscosity exhibits the same power law. The characteristic shear rate for the onset of these effects is determined by the activity. In the asymptotic limit of large activities, the shear-induced features become independent of activity and equal to those of passive polymers.