Non-coalescence of oppositely charged droplets in pH-sensitive emulsions
Non-coalescence of oppositely charged droplets in pH-sensitive emulsions
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DOI：
10.1073/pnas.1019196109
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发表时间：
2012-01-10
影响因子：
11.1
通讯作者：
Richtering, Walter
中科院分区：
文献类型：
--
作者：
Liu, Tingting;Seiffert, Sebastian;Richtering, Walter
同电荷稳定乳剂，相反电荷破坏乳剂。这是许多工业和实际过程的基本原则。使用微米大小的ph敏感聚合物水凝胶颗粒作为乳液稳定剂，我们制备了由相反电荷的液滴组成的乳液，这些液滴不会聚结。在散装乳化和微流体装置中，我们观察到带相反电荷的液滴不聚并，其中带相反电荷的液滴被迫在通道结内碰撞。结果表明，液滴之间的静电相互作用不能决定其稳定性，并揭示了软微凝胶颗粒稳定乳状液的独特的ph依赖特性。通过中和微凝胶可使非聚结转变为聚结，并可按需破乳。微凝胶稳定乳液的这种不寻常的特性为这些系统的未来应用提供了迷人的机会。
Like charges stabilize emulsions, whereas opposite charges break emulsions. This is the fundamental principle for many industrial and practical processes. Using micrometer-sized pH-sensitive polymeric hydrogel particles as emulsion stabilizers, we prepare emulsions that consist of oppositely charged droplets, which do not coalesce. We observe noncoalescence of oppositely charged droplets in bulk emulsification as well as in microfluidic devices, where oppositely charged droplets are forced to collide within channel junctions. The results demonstrate that electrostatic interactions between droplets do not determine their stability and reveal the unique pH-dependent properties of emulsions stabilized by soft microgel particles. The noncoalescence can be switched to coalescence by neutralizing the microgels, and the emulsion can be broken on demand. This unusual feature of the microgel-stabilized emulsions offers fascinating opportunities for future applications of these systems.