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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/8707
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dc.contributor.authorChanda, Sayantan-
dc.contributor.authorChandeshwar, Misra-
dc.contributor.authorRanjini, Bandyopadhyay-
dc.date.accessioned2026-04-15T05:11:32Z-
dc.date.available2026-04-15T05:11:32Z-
dc.date.issued2026-03-18-
dc.identifier.citationJournal of Applied Physics, 2026, Vol. 139 (111), AR No. 114701en_US
dc.identifier.issn1089-7550-
dc.identifier.urihttp://hdl.handle.net/2289/8707-
dc.descriptionOpen Access.en_US
dc.description.abstractColloidal microgel particles such as poly(N-isopropylacrylamide) (PNIPAM) shrink reversibly in an aqueous medium due to the expulsion of water at a volume phase transition temperature (VPTT) ~ 33  * C. Romeo et al. [Adv. Mater. 2010, 22, 3441–3445] had previously shown that dense aqueous PNIPAM suspensions transformed from one viscoelastic solid-like phase to another when suspension temperature was increased, with an intermediate viscoelastic liquid-like phase near the VPTT. They attributed this observation to a change in the inter-particle interaction from hydrophilic to hydrophobic. Here, we show using a combination of experimental techniques that particle hydrophobicity can become significant even below the VPTT. We achieve this by incorporating dissociating additives such as sodium chloride and potassium chloride, or non-dissociating additives such as sucrose, into the aqueous medium. Above the VPTT, we observe that suspension rigidity is the highest in the presence of salts because of the combined effects of electrostatic and hydrophobic attractions. In the presence of non-dissociating sucrose, in contrast, the inter-microgel interaction remains hydrophobic across the VPTT. Such easy tunability of interactions by incorporating commonly available chemicals into the suspension medium opens up new avenues for the synthesis of novel metamaterials.en_US
dc.language.isoenen_US
dc.publisherJournal of Applied Physicsen_US
dc.relation.urihttps://doi.org/10.48550/arXiv.2509.16651en_US
dc.relation.urihttps://doi.org/10.1063/5.0309685en_US
dc.rights© 2026 Author(s)en_US
dc.subjectColloidsen_US
dc.subjectElectrostaticsen_US
dc.subjectMetamaterialsen_US
dc.subjectMicrogelsen_US
dc.subjectPolymersen_US
dc.subjectScanning electron microscopyen_US
dc.subjectViscoelasticityen_US
dc.subjectHydrophobic effect,en_US
dc.subjectRheology and fluid dynamics,en_US
dc.subjectCarbohydratesen_US
dc.titleInvestigating the roles of hydrophobicity and electrostatics in the particle-scale dynamics and rheology of dense microgel suspensionsen_US
dc.typeArticleen_US
dc.additionalSpecial Collection: Mechanical Metamaterialsen_US
Appears in Collections:Research Papers (SCM)

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