Matsubara Hiroki, Tokiwa Yuhei, Masunaga Akihiro, Sakamoto Hiromu, Shishida Kazuki, Ohshima Kouki, Prause Albert, Gradzielski Michael
Graduate School of Advanced Science and Engineering, Hiroshima University, Kagamiyama 1-3-1, Higashi, Hiroshima 739-8526, Japan; Department of Chemistry, Faculty of Science, Kyushu University, Motooka 744, Nishi-Ku, 819-0395 Fukuoka, Japan.
Department of Chemistry, Faculty of Science, Kyushu University, Motooka 744, Nishi-Ku, 819-0395 Fukuoka, Japan.
Adv Colloid Interface Sci. 2024 Dec;334:103309. doi: 10.1016/j.cis.2024.103309. Epub 2024 Oct 9.
When n-alkanes or n-alcohols coexist with surfactants that have similar chain lengths, they can form mixed surface-frozen films at the oil-water interface. In this review, we first explain the basic characteristics of this surface freezing transition mainly from a thermodynamic viewpoint. Then, we discussed the effect of surface freezing of a cationic surfactant (cetyltrimethylammonium chloride: CTAC) with tetradecane, hexadecane, or hexadecanol on the kinetic stability of the oil-in-water (O/W) emulsions. We show that the surface frozen film not only increases the kinetic stability of the O/W emulsions but also stably encapsulates coexisting organic molecules in the oil core. Finally, we will introduce one of our recent works in which we observed that the exchange between silica nanoparticles and CTAC molecules occurs at the surface of Pickering emulsions when the oil-water interfacial tension is lowered by the surface freezing. The resulting detachment of silica particles from the oil-water interface broke the Pickering emulsion. The advantages of controlling the stability of O/W emulsions via the use of surface-frozen film are discussed in comparison with normal surfactant emulsifiers in the conclusion part of the review.
当正构烷烃或正构醇与具有相似链长的表面活性剂共存时，它们可在油水界面形成混合表面冻结膜。在本综述中，我们首先主要从热力学角度解释这种表面冻结转变的基本特征。然后，我们讨论了阳离子表面活性剂（十六烷基三甲基氯化铵：CTAC）与十四烷、十六烷或十六醇的表面冻结对水包油（O/W）乳液动力学稳定性的影响。我们表明，表面冻结膜不仅提高了O/W乳液的动力学稳定性，还能将共存的有机分子稳定地包裹在油核中。最后，我们将介绍我们最近的一项工作，即当通过表面冻结降低油水界面张力时，我们观察到在Pickering乳液表面发生了二氧化硅纳米颗粒与CTAC分子之间的交换。由此导致的二氧化硅颗粒从油水界面的脱离破坏了Pickering乳液。在综述的结论部分，我们将通过与普通表面活性剂乳化剂的比较，讨论利用表面冻结膜控制O/W乳液稳定性的优势。
