表面活性剂稳定乳液和皮克林乳液之间有区别吗？,Soft Matter

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表面活性剂稳定乳液和皮克林乳液之间有区别吗？
Soft Matter ( IF 2.9 ) Pub Date : 2023-02-13 , DOI: 10.1039/d2sm01375d
Riande I Dekker _{1,

2} , Santiago F Velandia _{1,

3} , Heleen V M Kibbelaar ₁ , Azeza Morcy ₁ , Véronique Sadtler ₃ , Thibault Roques-Carmes ₃ , Jan Groenewold ₂ , Willem K Kegel ₂ , Krassimir P Velikov _{1,

4} , Daniel Bonn ₁

Affiliation

哪些可测量的物理特性可以让人们区分表面活性剂稳定乳液和皮克林乳液？尽管表面活性剂通过降低油/水界面张力来影响油/水界面，但假设颗粒对界面张力影响很小。在这里，我们对三种不同的系统进行界面张力 (IFT) 测量：(1) 大豆油和水与乙基纤维素纳米颗粒 (ECNP)，(2) 硅油和水与球状蛋白牛血清白蛋白 (BSA)，和 (3 ) 十二烷基硫酸钠 (SDS) 溶液和空气。前两个系统包含颗粒，而第三个系统包含表面活性剂分子。我们观察到随着所有三个系统中颗粒/分子浓度的增加，界面张力显着降低。我们使用 Gibbs 吸附等温线和表面的 Langmuir 状态方程分析表面张力数据，导致基于粒子的系统具有惊人的高吸附密度。它们的行为似乎非常像表面活性剂系统：张力的降低是由于界面处存在许多粒子，每个粒子的吸附能为几k _B T。动态界面张力测量表明系统处于平衡状态，并且基于颗粒的系统的吸附特征时间尺度比表面活性剂长得多，这与它们的尺寸差异一致。此外，与表面活性剂稳定的乳液相比，基于颗粒的乳液显示出对聚结的稳定性较低。这使我们得出结论，我们无法明确区分表面活性剂稳定乳液和皮克林乳液。

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Is there a difference between surfactant-stabilised and Pickering emulsions?

What measurable physical properties allow one to distinguish surfactant-stabilised from Pickering emulsions? Whereas surfactants influence oil/water interfaces by lowering the oil/water interfacial tension, particles are assumed to have little effect on the interfacial tension. Here we perform interfacial tension (IFT) measurements on three different systems: (1) soybean oil and water with ethyl cellulose nanoparticles (ECNPs), (2) silicone oil and water with the globular protein bovine serum albumin (BSA), and (3) sodium dodecyl sulfate (SDS) solutions and air. The first two systems contain particles, while the third system contains surfactant molecules. We observe a significant decrease in interfacial tension with increasing particle/molecule concentration in all three systems. We analyse the surface tension data using the Gibbs adsorption isotherm and the Langmuir equation of state for the surface, resulting in surprisingly high adsorption densities for the particle-based systems. These seem to behave very much like the surfactant system: the decrease in tension is due to the presence of many particles at the interface, each with an adsorption energy of a few k_BT. Dynamic interfacial tension measurements show that the systems are in equilibrium, and that the characteristic time scale for adsorption is much longer for particle-based systems than for surfactants, in line with their size difference. In addition, the particle-based emulsion is shown to be less stable against coalescence than the surfactant-stabilised emulsion. This leaves us with the conclusion that we are not able to make a clear distinction between the surfactant-stabilised and Pickering emulsions.

更新日期：2023-02-13

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