Surfactant & Colloid Group, Department of Chemistry, University of Hull, Hull HU6 7RX, United Kingdom.
Langmuir. 2012 Jan 10;28(1):339-49. doi: 10.1021/la204104m. Epub 2011 Dec 19.
We have investigated the formation, drop sizes, and stability of emulsions prepared by hand shaking in a closed vessel in which the emulsion is in contact with a single type of surface during its formation. The emulsions undergo catastrophic phase inversion from oil-in-water (o/w) to water-in-oil (w/o) as the oil volume fraction is increased. We find that the oil volume fraction required for catastrophic inversion exhibits a linear correlation with the oil-water-solid surface contact angle. W/o high internal phase emulsions (HIPEs) prepared in this way contain water drops of diameters in the range 10-100 μm; emulsion drop size depends on the surfactant concentration and method of preparation. W/o HIPEs with large water drops show water separation but w/o HIPEs with small water drops are stable with respect to water separation for more than 100 days. The destabilization of the w/o HIPEs can be triggered by either evaporation of the oil continuous phase or by contact the emulsion with a solid surface of the "wrong" wettability.
我们研究了在封闭容器中通过手动摇晃制备乳液的形成、液滴尺寸和稳定性，在形成过程中乳液与单一类型的表面接触。随着油相体积分数的增加，乳液经历了从水包油（o/w）到油包水（w/o）的灾难性相转变。我们发现，发生灾难性反转所需的油相体积分数与油水固表面接触角呈线性相关。以这种方式制备的 w/o 高内相乳液（HIPE）含有直径在 10-100 μm 范围内的水滴；乳液液滴尺寸取决于表面活性剂浓度和制备方法。具有大水滴的 w/o HIPE 会发生水分分离，但具有小水滴的 w/o HIPE 在超过 100 天的时间内稳定，不会发生水分分离。w/o HIPE 的失稳可以通过油连续相的蒸发或乳液与具有“错误”润湿性的固体表面接触来触发。
