Magnetic Colloidal Particles as Probes for the Determination of the Structure of Laponite Suspensions

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• 作者：Fabrice Cousin ; Valé ; rie Cabuil ; and Pierre Levitz
• 刊名：Langmuir
• 出版年：2002
• 出版时间：March 5, 2002
• 年：2002
• 卷：18
• 期：5
• 页码：1466 - 1473
• 全文大小：108K
• 年卷期：v.18,no.5(March 5, 2002)
• ISSN：1520-5827

文摘

A new way to probe the microscopic structure of suspensions of discotic particles of Laponite is reported.Magnetic spherical colloidal particles of maghemite are incorporated into the Laponite suspensions tostudy their spatial repartition and their microrheological behavior. Chemicals conditions are found for thesynthesis of stable mixtures. The determination of the equation of state of the obtained mixtures by osmoticmeasurements shows that the inclusion of the probes does not modify the structure of Laponite suspensionswhich exhibit a fluid-solid transition at a given volume fraction. The transition is related to the appearanceof a pseudoplateau in the equation of state of the system. SANS and microrheological measurements showthat the probes are homogeneously dispersed in the mixture out ofthe pseudoplateau and that there isa microscopic phase separation between Laponite particles and maghemite probes in the region of thepseudoplateau of the equation of state. This microscopic phase separation is consistent with the descriptionof Laponite suspensions as microscopically segregated in the region of the pseudoplateau.