Salt-induced stability and modified interfacial energetics in self-faceting emulsion droplets
Salt-induced stability and modified interfacial energetics in self-faceting emulsion droplets
复制标题
自面乳液液滴中盐诱导的稳定性和改进的界面能量学
DOI：
10.1016/j.jcis.2022.03.146
复制
发表时间：
2022
影响因子：
9.9
通讯作者：
Sloutskin, Eli
中科院分区：
文献类型：
--
作者：
Nanikashvili, Pilkhaz M.;Butenko, Alexander V.;Deutsch, Moshe;Lee, Daeyeon;Sloutskin, Eli
假设水悬浮的、表面稳定的液体油滴的违反直觉的温度控制的自刻面为智能液体的工程设计提供了新的机会，智能液体的性质可以通过外部刺激来控制。然而，由于表面活性剂沉淀，许多表现出自刻面现象的乳液具有有限的稳定性。通过改变添加盐的浓度来控制电荷屏蔽，可以提高乳液的稳定性，并调节其液滴间的静电斥力。此外，在许多技术相关的情况下，盐可能已经存在于乳液的水相中。然而，盐对自我刻面效应的影响从未被探索过。我们假设，自刻面转变的温度，和对表面活性剂沉淀的稳定性，离子表面活性剂稳定的乳液显着修改由salt introducing.ExperimentsWe探讨了温度依赖性的影响，NaCl和CsCl盐浓度对乳液的相图，采用光学显微镜的乳液液滴形状和界面张力测量，两者都敏感的界面相变。FindingsA盐浓度依赖的增加，在自刻面转变温度被发现，其机制阐明。我们的研究结果允许显着提高乳液的稳定性，并提供必要的物理理解，为未来的研究进展和应用的自刻面现象在含盐乳液。
HypothesisThe counterintuitive temperature-controlled self-faceting of water-suspended, surfactant-stabilized, liquid oil droplets provides new opportunities in engineering of smart liquids, the properties of which are controllable by external stimuli. However, many emulsions exhibiting self-faceting phenomena have limited stability due to surfactant precipitation. The emulsions’ stability may be enhanced, and their inter-droplet electrostatic repulsion tuned, through controlled charge screening driven by varying-concentration added salts. Moreover, in many technologically-relevant situations, salts may already exist in the emulsion’s aqueous phase. Yet, salts’ impact on self-faceting effects has never been explored. We hypothesize that the self-faceting transitions’ temperatures, and stability against surfactant precipitation, of ionic-surfactants-stabilized emulsions are significantly modified by salt introduction.ExperimentsWe explore the temperature-dependent impact of NaCl and CsCl salt concentration on the emulsions’ phase diagrams, employing optical microscopy of emulsion droplet shapes and interfacial tension measurements, both sensitive to interfacial phase transitions.FindingsA salt concentration dependent increase in the self-faceting transition temperatures is found, and its mechanism elucidated. Our findings allow for a significant enhancement of the emulsions’ stability, and provide the physical understanding necessary for future progress in research and applications of self-faceting phenomena in salt-containing emulsions.