Evidence for re-entrant behavior in laponite–PEO systems

Baghdadi, Hossein A. and Jensen, Elizabeth C. and Easwar, Nalini and Bhatia, Surita R.. (2008) Evidence for re-entrant behavior in laponite–PEO systems. Rheologica Acta, 47 (2). pp. 121-127. ISSN 0035-4511

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We observe evidence of re-entrant behavior in dispersions of a discotic clay, laponite, with added polymer. Under basic conditions, neat laponite forms a disordered colloidal glass. Rheologically, this phase behaves as a viscoelastic solid, and dynamic light scattering shows evidence of non-ergodic behavior. Addition of low molecular weight poly(ethylene oxide) (PEO) melts the glass, resulting in a low-viscosity liquid with fast dynamics. We believe this is due to a depletion force caused by excess PEO chains in solution. A viscoelastic solid is re-formed with the addition of high molecular weight PEO, which we believe to be caused by polymer chains bridging between laponite particles. The physics in our system is quite different from the hard sphere/nonadsorbing polymer systems for which re-entrant glass transitions have been reported in the literature; however, we believe there may be similarities between these phenomena. To our knowledge, this is the first evidence of a type of re-entrant behavior in anisotropic colloids.

Item Type: Article
InterNano Taxonomy: Nanomanufacturing Processes > Deposition of Nanostructured Films or Nanostructures > Adsorption
Nanomanufacturing Processes > Nanocomposite Manufacturing > Clay dispersion
Nanoscale Objects and Nanostructured Materials > Nanocomposites > Polymeric
Nanomanufacturing Characterization Techniques
Collections: Nanomanufacturing Research Collection > Nanomanufacturing Nanoscale Science and Engineering Centers > Center for Hierarchical Manufacturing
Nanomanufacturing Research Collection
Depositing User: Moureen Kemei
Date Deposited: 16 Feb 2010 15:55
Last Modified: 19 Sep 2011 20:49
URI: http://eprints.internano.org/id/eprint/272

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