Structure and Dynamics of Loosely Cross-Linked Ionic Microgel Dispersions in the Fluid Regime

Holmqvist, P.; Nägele, G.; Schurtenberger, P.; Mohanty, P.S.; Heinen, M.

doi:10.1103/PhysRevLett.109.048302

Journal Article

PreJuSER-111854

Structure and Dynamics of Loosely Cross-Linked Ionic Microgel Dispersions in the Fluid Regime

Holmqvist, P.FZJ* ; Mohanty, P. S. ; Nägele, G.FZJ* ; Schurtenberger, P. ; Heinen, M.

2012
APS College Park, Md.

Physical review letters 109, 048302 (2012) [10.1103/PhysRevLett.109.048302]

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Please use a persistent id in citations: http://hdl.handle.net/2128/7804 doi:10.1103/PhysRevLett.109.048302

Abstract: We report a comprehensive experimental-theoretical study of the temperature-and concentration-dependent swelling behavior of weakly cross-linked PNiPAm ionic microgel particles in the deionized fluid phase. The particles swell reversibly when the dispersion is cooled from the collapsed state to lower temperatures. While the collapsed state shows no dependence on the microgel number density, the swelling at lower T is more pronounced at lower concentrations. The static pair correlations and short-time diffusion functions, and the concentration and temperature dependence of the microgel radius and effective charge, are studied using static and dynamic light scattering in combination with state-of-the-art analytical theoretical schemes based on a Yukawa-type effective pair potential and a core-shell model. We show that only such a combined, simultaneous fit of static and dynamic scattering functions allows for an unambiguous determination of the microgel radius and effective charge.

Keyword(s): J

Classification:

Physics, Multidisciplinary

Note: We thank Simon Rogers (Research Centre Julich) for carefully proofreading the letter. P. S. M. and P. S. acknowledge financial support from the Swiss National Science Foundation. G. N. and M. H. acknowledge support from the Deutsche Forschungsgemeinschaft (project B2 in SFB-TR6).

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