Haider Olivia M, Walker Lynn M
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
Langmuir. 2025 Aug 19;41(32):21415-21424. doi: 10.1021/acs.langmuir.5c01946. Epub 2025 Aug 7.
Fluid/fluid interfaces stabilized with strongly adsorbed solid nanoparticles are implemented in industries including cosmetics, pharmaceuticals, and food science. Solid particles at the interface result in complex interfacial mechanics, which are highly dependent on interfacial particle behavior and bulk properties of both fluid phases. Many interfacial studies have been conducted characterizing the effects of the aqueous fluid properties such as particle chemistry, pH, temperature, salinity, and the impact of surfactant and other additives on interfacial mechanics and adsorption behavior. However, the role of the hydrophobic phase on interfacial stability, as well as the adsorption and organization of interfacial material, is less understood. In this work, mechanical properties of particle-laden interfaces are characterized at oil/water and air/water interfaces to determine the impact of the hydrophobic fluid on particle jamming at the fluid/fluid interface. A model aqueous phase containing CTAB-SiO (cationic surfactant-anionic nanoparticle) complexes is used to deliver particles to air/water, dodecane/water, and silicone oil/water interfaces using a fixed adsorption protocol. Adsorption dynamics and interfacial rheology are measured on microscale using a microtensiometer platform. Results show that under the same aqueous conditions, the hydrophobic phase impacts the effective areal coverage of particles at the interface. When subjected to nonlinear compression cycles, interfacial jamming is impacted by particle wettability and electrostatic interactions between adsorbed particles. These findings suggest that the nonpolar phase has a significant impact on the lateral interactions between particles at the interface. This work highlights how changes to the hydrophobic fluid introduce additional complexities to the interfacial properties and further the understanding of solid particle interactions at different fluid interfaces for controlled emulsion design.
由牢固吸附的固体纳米颗粒稳定的流体/流体界面应用于化妆品、制药和食品科学等行业。界面处的固体颗粒会导致复杂的界面力学，这高度依赖于界面颗粒行为和两相流体的本体性质。已经进行了许多界面研究，以表征水性流体性质（如颗粒化学性质、pH值、温度、盐度）以及表面活性剂和其他添加剂对界面力学和吸附行为的影响。然而，疏水相对界面稳定性以及界面材料的吸附和组织的作用却鲜为人知。在这项工作中，通过表征油/水和空气/水界面处含颗粒界面的力学性能，来确定疏水流体对流体/流体界面处颗粒堵塞的影响。使用含有CTAB-SiO（阳离子表面活性剂-阴离子纳米颗粒）络合物的模型水相，通过固定吸附方案将颗粒输送到空气/水、十二烷/水和硅油/水界面。使用微张力计平台在微观尺度上测量吸附动力学和界面流变学。结果表明，在相同的水性条件下，疏水相影响界面处颗粒的有效面积覆盖率。当受到非线性压缩循环时，界面堵塞会受到颗粒润湿性和吸附颗粒之间静电相互作用的影响。这些发现表明，非极性相对界面处颗粒之间的横向相互作用有重大影响。这项工作突出了疏水流体的变化如何给界面性质带来额外的复杂性，并进一步加深了对不同流体界面处固体颗粒相互作用的理解，以用于可控乳液设计。
