Binks Bernard P, Tyowua Andrew T
Department of Chemistry, University of Hull , Hull HU6 7RX, U.K.
Langmuir. 2016 Apr 5;32(13):3110-5. doi: 10.1021/acs.langmuir.6b00140. Epub 2016 Mar 22.
The preparation of powdered water-in-oil (w/o) emulsions by gentle aeration of w/o emulsions stabilized by hydrophobic fumed silica particles in the presence of oleophobic fluorinated clay particles is reported for an alkane and a triglyceride oil. The resultant powders consist of water drops dispersed in oil globules themselves dispersed in air (w/o/a). They contain ∼80 wt % of the precursor w/o emulsion and were stable to phase separation for over 1 year but release oil and water when sheared on a substrate. Above a certain ratio of w/o emulsion:fluorinated clay particles, the powdered emulsions partially invert to an emulsion paste, composed of air bubbles and water droplets dispersed in oil. The tap density and angle of repose of the powdered emulsions were measured and compared with those of the corresponding powdered oils making up the continuous phase of the precursor emulsions. The contact angles of water droplets under oil on glass slides spin coated with silica particles and oil drops and w/o emulsion droplets in air on compressed disks of fluorinated clay particles are consistent with the stabilization of w/o emulsions and powdered emulsions, respectively.
本文报道了在疏油性氟化粘土颗粒存在的情况下，通过对由疏水性气相二氧化硅颗粒稳定的油包水（w/o）乳液进行温和曝气，制备烷烃和甘油三酯油的粉状油包水乳液。所得粉末由分散在油滴中的水滴组成，而油滴又分散在空气中（w/o/a）。它们含有约80 wt%的前体w/o乳液，并且在一年多的时间内对相分离稳定，但在底物上剪切时会释放出油和水。当w/o乳液与氟化粘土颗粒的比例超过一定值时，粉状乳液会部分转化为乳液糊，该乳液糊由分散在油中的气泡和水滴组成。测量了粉状乳液的振实密度和休止角，并与构成前体乳液连续相的相应粉状油的振实密度和休止角进行了比较。水滴在涂有二氧化硅颗粒的玻璃载玻片上油下的接触角以及油滴和w/o乳液滴在氟化粘土颗粒压缩盘上空气中的接触角分别与w/o乳液和粉状乳液的稳定性一致。
