Phase inversion of particle-stabilized materials from foams to dry water
Phase inversion of particle-stabilized materials from foams to dry water
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DOI：
10.1038/nmat1757
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发表时间：
2006-11-01
期刊：
影响因子：
41.2
通讯作者：
Murakami, Ryo
中科院分区：
文献类型：
--
作者：
Binks, Bernard P.;Murakami, Ryo
附着在液体表面的小颗粒出现在许多产品和过程中，包括原油乳液和食品泡沫以及浮选，人们对研究它们的行为重新产生了兴趣。具有适当润湿性的胶体颗粒强烈吸附在液-液和液-汽界面(1)上，并且可以分别作为乳液(2)和泡沫(3)的唯一稳定剂。新材料，包括胶体体(4)、各向异性颗粒(5)和多孔固体(6)，都是通过在这些界面上组装颗粒来制备的。颗粒稳定乳液从水包油到油包水的相转化可以通过改变颗粒疏水性（过渡性）7 或通过改变油/水比（灾难性）(8) 来实现。在这里，我们描述了颗粒稳定的空气-水系统的相转化，从水包空气泡沫到空气包水粉末，反之亦然。这种反转可以通过恒定空气/水比下二氧化硅颗粒疏水性的逐渐变化或通过改变固定颗粒润湿性下的空气/水比来驱动，并且在由表面活性剂稳定的相应系统中尚未观察到。这项工作的简单之处在于，这种新颖的反演是在单个系统中实现的。所得材料中封装有空气或水，在食品、制药和化妆品行业具有潜在的应用前景。
Small particles attached to liquid surfaces arise in many products and processes, including crude-oil emulsions and food foams and in flotation, and there is a revival of interest in studying their behaviour. Colloidal particles of suitable wettability adsorb strongly to liquid-liquid and liquid vapour interfaces(1), and can be sole stabilizers of emulsions(2) and foams(3), respectively. New materials, including colloidosomes(4), anisotropic particles(5) and porous solids(6), have been prepared by assembling particles at such interfaces. Phase inversion of particle-stabilized emulsions from oil in water to water in oil can be achieved either by variation of the particle hydrophobicity ( transitional) 7 or by variation of the oil/water ratio ( catastrophic)(8). Here we describe the phase inversion of particle-stabilized air-water systems, from air-in-water foams to water-in-air powders and vice versa. This inversion can be driven either by a progressive change in silica-particle hydrophobicity at constant air/water ratio or by changing the air/water ratio at fixed particle wettability, and has not been observed in the corresponding systems stabilized by surfactants. The simplicity of the work is that this novel inversion is achieved in a single system. The resultant materials in which either air or water become encapsulated have potential applications in the food, pharmaceutical and cosmetics industries.