Silva Gonçalo M C, Morgado Pedro, Filipe Eduardo J M
Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Departamento de Engenharia Química, Universidade de Lisboa, 1049-001 Lisbon, Portugal.
Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Departamento de Engenharia Química, Universidade de Lisboa, 1049-001 Lisbon, Portugal.
J Colloid Interface Sci. 2024 Jan 15;654(Pt B):906-914. doi: 10.1016/j.jcis.2023.10.100. Epub 2023 Oct 20.
Aqueous solutions of mixtures of hydrogenated and perfluorinated ionic surfactants are known to display anomalous aggregation behavior due to the mutual phobicity between hydrogenated and perfluorinated chains. Despite all efforts, different experimental limitations prevented so far a definite interpretation of the existing experimental results: both intermicellar and intramicellar segregation remain acceptable possibilities.
The potential for segregation of mixtures of fluorinated and hydrogenated ionic surfactants in water was assessed using atomistic molecular dynamics simulations. Aqueous mixtures of hydrogenated and perfluorinated ionic surfactants were studied: mixtures of anionic surfactants (sodium dodecylsulfate (SDS) + sodium perfluoro-octanoate (SPFO)) and catanionic surfactants (decyltrimethylammonium bromide (DeTAB) + SPFO) were simulated.
The mixture of anionic surfactants, SDS + SPFO, exhibits clear intramicellar segregation between fluorinated and hydrogenated chains, displaying hydrogenous-rich and fluorous-rich regions. Compartmentalized micelles are thus clearly formed. The simulation results also suggest the possibility of intermicellar segregation. Conversely, catanionic mixtures of DeTAB and SPFO in water solution assemble into a large oblate structure, containing all available molecules in the simulation box, resembling a double layer membrane or a vesicle wall. In this case mixing between fluorinated and hydrogenated surfactants is dictated by charge alternation.
氢化离子表面活性剂和全氟离子表面活性剂混合物的水溶液因氢化链和全氟链之间的相互疏水性而呈现异常聚集行为。尽管付出了诸多努力，但不同的实验局限性迄今阻碍了对现有实验结果的明确解释：胶束间和胶束内的分离仍是可行的可能性。
使用原子分子动力学模拟评估含氟和氢化离子表面活性剂在水中混合物的分离可能性。研究了氢化离子表面活性剂和全氟离子表面活性剂的水性混合物：模拟了阴离子表面活性剂（十二烷基硫酸钠（SDS）+全氟辛酸钠（SPFO））和阴阳离子表面活性剂（癸基三甲基溴化铵（DeTAB）+SPFO）的混合物。
阴离子表面活性剂混合物SDS+SPFO在含氟链和氢化链之间表现出明显的胶束内分离，呈现富氢区和富氟区。因此清晰地形成了分隔的胶束。模拟结果还表明了胶束间分离的可能性。相反，水溶液中DeTAB和SPFO的阴阳离子混合物组装成一个大的扁球形结构，包含模拟盒中的所有可用分子，类似于双层膜或囊泡壁。在这种情况下，含氟和氢化表面活性剂之间的混合由电荷交替决定。
