Guan Xin, Ngai To
Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
Langmuir. 2021 Mar 2;37(8):2843-2854. doi: 10.1021/acs.langmuir.0c03658. Epub 2021 Feb 17.
Synergistic stabilization of Pickering emulsions by a mixture of surfactants and colloidal particles has received increasing interest in recent years but only a few of them can produce high internal phase double emulsions (HIPDEs) with good stability. In this study, we present a feasible and common method of preparing Pickering high internal phase emulsions (HIPEs) with tunable inner morphology costabilized by a biosurfactant lecithin and silica nanoparticles. We investigate the influence of the pH value on the interfacial behavior of lecithin and elucidate the synergistic mechanism between lecithin and silica nanoparticles in different conditions in the stability of as-prepared emulsions. Specifically, water-in-oil (W/O) Pickering HIPEs can be successfully stabilized by lecithin and hydrophobic silica nanoparticles in a wide pH range (pH 1-10), while catastrophic phase inversion occurred at high pH values (pH ≥ 11). Interestingly, stable water-in-oil-in-water (W/O/W) high internal phase double emulsions (HIPDEs) can also be prepared via a two-step method by the cooperation of lecithin and silica nanoparticles. Moreover, functional interconnected porous monoliths and microspheres are facilely fabricated by emulsion templates and their potential applications are explored.
近年来，表面活性剂和胶体颗粒混合物对皮克林乳液的协同稳定作用越来越受到关注，但其中只有少数能够制备出具有良好稳定性的高内相双乳液（HIPDEs）。在本研究中，我们提出了一种可行且通用的方法，用于制备由生物表面活性剂卵磷脂和二氧化硅纳米颗粒协同稳定、内部形态可调的皮克林高内相乳液（HIPEs）。我们研究了pH值对卵磷脂界面行为的影响，并阐明了在不同条件下卵磷脂与二氧化硅纳米颗粒在制备的乳液稳定性方面的协同机制。具体而言，油包水（W/O）型皮克林HIPEs能够在较宽的pH范围（pH 1 - 10）内通过卵磷脂和疏水性二氧化硅纳米颗粒成功稳定，而在高pH值（pH≥11）时会发生灾难性的相转变。有趣的是，通过卵磷脂和二氧化硅纳米颗粒的协同作用，还可以通过两步法制备出稳定的水包油包水（W/O/W）型高内相双乳液（HIPDEs）。此外，利用乳液模板可轻松制备功能性互连多孔整体材料和微球，并探索了它们的潜在应用。
