Influence of surfactant structure on the double inversion of emulsions in the presence of nanoparticles

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• 作者：Bernard P. Binks ; Jhonny A. Rodrigues
• 关键词：Emulsion inversion ; Surfactant ; Nanoparticle ; Solid-stabilised emulsion ; Double inversion
• 刊名：Colloids and Surfaces A: Physicochemical and Engineering Aspects
• 出版年：2009
• 出版时间：5 August 2009
• 年：2009
• 卷：345
• 期：1-3
• 页码：195-201
• 全文大小：1693 K

文摘

The double inversion of emulsions from oil-in-water (o/w) to water-in-oil (w/o) and back to o/w is a novel approach developed using oppositely charged mixtures of solid particles and surfactant molecules [B.P. Binks, J.A. Rodrigues, Angew. Chem. Int. Ed. 46 (2007) 5389]. This work extends these preliminary results reported for the cationic surfactant di-decyldimethylammonium bromide (di-C₁₀DMAB), by studying the influence of surfactant chain length for symmetrical cationic surfactants. Two double-chain surfactants with hydrocarbon chain lengths of 8 or 12 are used here to stabilise emulsions with dodecane in the presence of silica nanoparticles (Ludox HS-30). Double inversion of emulsions is also possible with these surfactants. However, multiple emulsions of both types are observed when the most hydrophobic surfactant di-C₁₂DMAB is used, occurring near the boundaries of the first and second inversion, respectively. A phase diagram is introduced, in which the double inversion of emulsions occurs at various particle-to-surfactant ratios, in particular at low concentrations of silica particles between 0.1 and 4 wt. % .