Effects of Added Silica Nanoparticles on the Nematic Liquid Crystal Phase Formation in Beidellite Suspensions

In this article, we present a study of the liquid crystal phase behavior of mixed suspensions of the natural smectite clay mineral beidellite and nonadsorbing colloidal silica particles. While virtually all smectite clays dispersed in water form gels at very low concentrations, beidellite displays a...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2014-05, Vol.118 (18), p.4913-4919
Main Authors: Landman, Jasper, Paineau, Erwan, Davidson, Patrick, Bihannic, Isabelle, Michot, Laurent J, Philippe, Adrian-Marie, Petukhov, Andrei V, Lekkerkerker, Henk N. W
Format: Article
Language:English
Subjects:
Continental interfaces, environment
Formations
Liquid crystals
Nanospheres
Nematic
Phase separation
Phase transformations
Sciences of the Universe
Silicon dioxide
Smectites
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Summary:In this article, we present a study of the liquid crystal phase behavior of mixed suspensions of the natural smectite clay mineral beidellite and nonadsorbing colloidal silica particles. While virtually all smectite clays dispersed in water form gels at very low concentrations, beidellite displays a first order isotropic–nematic phase transition before gel formation ( J. Phys. Chem. B, 2009, 113, 15858−15869 ). The addition of silica nanospheres shifts the concentrations of the coexisting isotropic and nematic phases to slightly higher values while at the same time markedly accelerating the phase separation process. Furthermore, beidellite suspensions at volume fractions above the isotropic–nematic phase separation, trapped in a kinetically arrested gel state, liquefy on the addition of silica nanospheres and proceed to isotropic–nematic phase separation. Using small-angle X-ray scattering (SAXS), we probe the structural changes caused by the addition of the silica nanospheres, and we relate the modification of the phase transition kinetics to the change of the rheological properties.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp500036v