School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China.
Lab Chip. 2013 Oct 21;13(20):4047-52. doi: 10.1039/c3lc50638j. Epub 2013 Aug 15.
Multiple emulsions, which are widely applied in a myriad of fields because of their unique ability to encapsulate and protect active ingredients, are typically produced by sequential drop-formations and drop-encapsulations using shear-induced emulsification. Here we report a qualitatively novel method of creating highly controlled multiple emulsions from lower-order emulsions. By carefully controlling the interfacial energies, we adjust the spreading coefficients between different phases to cause drops of one fluid to completely engulf other drops of immiscible fluids; as a result multiple emulsions are directly formed by simply putting preformed lower-order emulsion drops together. Our approach has highly controllable flexibility. We demonstrate this in preparation of both double and triple emulsions with a controlled number of inner drops and precisely adjusted shell thicknesses including ultra-thin shells. Moreover, this controllable drop-engulfing-drop approach has a high potential in further investigations and applications of microfluidics. Importantly, this innovative approach opens a window to exploit new phenomena occurring in fluids at the microscale level, which is of great significance for developing novel microfluidics.
多重乳状液由于其独特的封装和保护活性成分的能力而被广泛应用于众多领域，通常通过顺序的滴形成和使用剪切诱导乳化的滴包封来生产。在这里，我们报道了一种从低阶乳状液中创造高度可控的多重乳状液的定性新方法。通过仔细控制界面能，我们调整不同相之间的铺展系数，使一种流体的液滴完全包裹另一种不混溶流体的液滴；结果，只需将预先形成的低阶乳状液滴放在一起，就可以直接形成多重乳状液。我们的方法具有高度可控的灵活性。我们通过用受控数量的内相液滴和精确调整的壳厚度（包括超薄壳）来制备双乳液和三乳液来证明这一点。此外，这种可控的包裹液滴的方法在微流控的进一步研究和应用中具有很高的潜力。重要的是，这种创新的方法为探索微尺度下流体中发生的新现象开辟了一扇窗口，这对于开发新型微流控技术具有重要意义。
