Zhu Yue, Chen Tingting, Cui Zhenggang
School of Chemistry and Chemical Engineering, Nantong University, Nantong, China.
The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, China.
Front Chem. 2022 Aug 19;10:950932. doi: 10.3389/fchem.2022.950932. eCollection 2022.
Multiple emulsions are widely used in pharmaceuticals, foods, and cosmetics. However, those stabilized by surfactants with different HLB values are generally unstable due to the diffusion of the surfactants between inner and outer interfaces. Here, we report that multiple W/O/W emulsions can be prepared by using the same particles in combination with a surfactant of different concentrations. The less surface-active raw CaCO nanoparticles can be hydrophobized to surface-active by adsorption of the anionic surfactant SDS, and the wettability of the particles can be controlled to be suitable for stabilizing both O/W and W/O Pickering emulsions by adjusting the surfactant concentration. With toluene as oil phase, the CaCO particles at 1.0 wt% tend to stabilize a W/O emulsion in the presence of 3 mm SDS in an aqueous solution, which can then be further dispersed in an aqueous phase with 1.0 wt% CaCO and SDS below 1 mm to form a W/O/W multiple emulsion. The effects of the ratio of W/O emulsion to the outer water phase and the preparation methods on stabilization of multiple emulsions were examined. With a ratio smaller than 3:1 and by gentle magnetic stirring, the multiple emulsions obtained can stay stable for at least a month without coalescence. This simple method not only ensures stabilization of multiple emulsions but also avoids complicated synthesis of colloid particles with different wettability.
多重乳液广泛应用于制药、食品和化妆品领域。然而，那些由具有不同亲水亲油平衡（HLB）值的表面活性剂稳定的多重乳液，由于表面活性剂在内外界面之间的扩散，通常是不稳定的。在此，我们报告了通过使用相同的颗粒与不同浓度的表面活性剂相结合，可以制备多重水包油包水（W/O/W）乳液。表面活性较低的未处理碳酸钙（CaCO）纳米颗粒可以通过吸附阴离子表面活性剂十二烷基硫酸钠（SDS）而被疏水化，从而具有表面活性，并且通过调节表面活性剂浓度，可以将颗粒的润湿性控制在适合同时稳定水包油（O/W）和油包水（W/O）皮克林乳液的范围内。以甲苯为油相，在水溶液中存在3 mM SDS的情况下，1.0 wt%的CaCO颗粒倾向于稳定W/O乳液，然后可以将其进一步分散在含有1.0 wt% CaCO且SDS浓度低于1 mM的水相中，以形成W/O/W多重乳液。研究了W/O乳液与外部水相的比例以及制备方法对多重乳液稳定性的影响。当比例小于3:1并通过温和的磁力搅拌时，得到的多重乳液可以保持稳定至少一个月而不发生聚结。这种简单的方法不仅确保了多重乳液的稳定性，还避免了合成具有不同润湿性的胶体颗粒的复杂过程。
