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Hypothesis: While the mechanical disruption of microscopic structures incomplex fluids by large shear flows has been studied extensively, the effectsof applied strains on the dielectric properties of macromolecular aggregateshas received far less attention. Simultaneous rheology and dielectricexperiments can be employed to study the dynamics of sheared colloidalsuspensions over spatiotemporal scales spanning several decades.  Experiments: Using a precision impedance analyzer, we study the dielectricbehavior of strongly sheared aqueous suspensions of thermoreversible hydrogelpoly(N-isopropylacrylamide) (PNIPAM) particles at different temperatures. Wealso perform stress relaxation experiments to uncover the influence of largedeformations on the bulk mechanical moduli of these suspensions.  Findings: The real parts of the complex dielectric permittivities of all thesheared PNIPAM suspensions exhibit distinct relaxation processes in the low andhigh frequency regimes. At a temperature below the lower consolute solutiontemperature (LCST), both real and imaginary parts of the permittivities ofhighly dense PNIPAM suspensions decrease with increase in applied oscillatorystrain amplitudes. Simultaneously, we note a counter-intuitive slowdown of thedielectric relaxation dynamics. Contrary to our rheo-dielectric findings, ourbulk rheology experiments, performed under identical conditions, revealshear-thinning dynamics with increasing strain amplitudes. We propose theshear-induced rupture of fragile clusters of swollen PNIPAM particles toexplain our observations.  Keywords : Rheo-dielectric; Thermoresponsive hydrogels; Segmental motion;Counterion polarization; Interfacial polarization; Dense suspensions; Rheology;Shear-thinning.

Dichotomous behaviors of stress and dielectric relaxations in dense suspensions of swollen thermoreversible hydrogel microparticles