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Issue 42, 2012
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Deformable particles with anisotropic interactions: unusual field-induced structural transitions in ultrasoft ionic microgel colloids

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Abstract

Ionic microgels are intriguing soft and deformable colloids with an effective pair potential that crosses over from Yukawa-like at large distances to a much softer repulsive interaction at short distances. Here we report the effect of adding an anisotropic dipolar contribution to colloids with such “ultra-soft” interactions. We use an alternating electric field to induce a tunable dipolar contribution, and study the resulting particle self-assembly and phase transitions in situ with confocal laser scanning microscopy. We find significant field-induced structural transitions at low as well as at very high effective volume fractions. At ϕeff = 0.1 we observe a transition from an isotropic to a string fluid. At ϕeff = 0.85, there is a reversible transition from an amorphous to a dipolar crystalline state, followed by the onset of a gas–(string) solid coexistence. At ϕeff = 1.6 and 2.0, i.e. far above close packing, evidence for a field-induced arrested phase separation is found.

Graphical abstract: Deformable particles with anisotropic interactions: unusual field-induced structural transitions in ultrasoft ionic microgel colloids

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Publication details

The article was received on 26 Jul 2012, accepted on 27 Aug 2012 and first published on 12 Sep 2012


Article type: Communication
DOI: 10.1039/C2SM26729B
Citation: Soft Matter, 2012,8, 10819-10822
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    Deformable particles with anisotropic interactions: unusual field-induced structural transitions in ultrasoft ionic microgel colloids

    P. S. Mohanty, A. Yethiraj and P. Schurtenberger, Soft Matter, 2012, 8, 10819
    DOI: 10.1039/C2SM26729B

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