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dc.contributor.authorMisra, Chandeshwar-
dc.contributor.authorGadige, Paramesh-
dc.contributor.authorBandyopadhyay, Ranjini-
dc.identifier.citationJournal of Colloid and Interface Science - A, 2023, Vol. 630, p223en_US
dc.descriptionRestricted Access.en_US
dc.description.abstractHypothesis: 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 macro- molecular aggregates have 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: All the sheared PNIPAM suspensions exhibit distinct dielectric relaxation processes in the low and high frequency regimes. At a temperature below the lower consolute solution temperature (LCST), the complex permittivities of highly dense PNIPAM suspensions decrease with increase in applied oscilla- tory 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 iden- tical 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. Our work illus- trates that rheo-dielectric studies have enormous potential for providing deep insights into the length scale-dependent dynamical properties of complex systems such as dense suspensions and soft glasses.en_US
dc.rights2022 Elsevieren_US
dc.subjectThermoresponsive hydrogelsen_US
dc.subjectSegmental motionen_US
dc.subjectCounterion polarizationen_US
dc.subjectInterfacial polarizationen_US
dc.subjectDense suspensionsen_US
dc.titleDichotomous behaviors of stress and dielectric relaxations in dense suspensions of swollen thermoreversible hydrogel microparticlesen_US
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