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