La Mesa Camillo, Risuleo Gianfranco
Department of Chemistry, Sapienza University of Rome, Rome, Italy.
Department of Biology and Biotechnologies Charles Darwin, Sapienza University of Rome, Rome, Italy.
Front Chem. 2021 Dec 14;9:790873. doi: 10.3389/fchem.2021.790873. eCollection 2021.
The surface activity of surfactant mixtures is critically analyzed. Cat-anionic systems, in which two ionic species are mixed in non-stoichiometric ratios, are considered. With respect to the solution behavior, where a substantial decrease of is met compared to the pure components, a moderate effect on surface tension, γ, occurs. Compared to the pure species, the decrease of surface tension for such mixtures is not significant, and no clear dependence on the mole fraction anionic/cationic is met. The surface tension is grossly constant in the whole concentration range. Conversely, the interaction parameter for surfaces, (calculated by the regular solution theory), is more negative than that for micelle formation, . This fact suggests that the desolvation of polar heads of the two species at interfaces is largely different. Very presumably, the underlying rationale finds origin in the sizes and solvation of both polar head groups.
对表面活性剂混合物的表面活性进行了严格分析。考虑了阳离子 - 阴离子体系，其中两种离子物种以非化学计量比混合。关于溶液行为，与纯组分相比，溶液行为出现显著下降，对表面张力γ产生适度影响。与纯物质相比，此类混合物的表面张力下降并不显著，且未发现表面张力与阴离子/阳离子摩尔分数有明显相关性。在整个浓度范围内，表面张力基本保持恒定。相反，表面相互作用参数（由正规溶液理论计算得出）比胶束形成的相互作用参数更负。这一事实表明，两种物种极性头在界面处的去溶剂化情况有很大差异。很可能，其根本原因源于两个极性头基团的大小和溶剂化作用。
