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Issue 24, 2000
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Pickering emulsions stabilised by Laponite clay particles

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Abstract

The type and stability of Pickering emulsions stabilised by disc-like Laponite RD clay particles are described. By establishing the phase diagram of aqueous dispersions as a function of clay and salt (NaCl) concentration, we deduce that toluene-in-water (o/w) emulsions, stable to creaming and coalescence for at least 6 months, are only formed under conditions where the colloidal particles are flocculated. The initial average drop diameter is independent of clay concentration but depends markedly on oil volume fraction, ranging from 10 to 28 μm. Changes in the drop size distributions with time are shown to be due to Ostwald ripening, which, due to the irreversible nature of particle adsorption at oil/water interfaces, is rapid at first and ceases completely at long times. It is suggested that ripening is arrested when the Laplace pressure inside drops of different sizes becomes equal. For optimum conditions, emulsions prepared using a variety of oils including non-polar alkanes and polar alcohols are always o/w even at high oil phase volume fraction, reflecting the hydrophilic nature of this synthetic clay in oil–water systems.

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Publication details

The article was received on 31 Aug 2000, accepted on 25 Oct 2000 and first published on 24 Nov 2000


Article type: Paper
DOI: 10.1039/B007098J
Phys. Chem. Chem. Phys., 2000,2, 5640-5646

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    Pickering emulsions stabilised by Laponite clay particles

    N. P. Ashby and B. P. Binks, Phys. Chem. Chem. Phys., 2000, 2, 5640
    DOI: 10.1039/B007098J

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