Biosurfactants show synergic effects with synthesized surfactant in reducing hydrophobic/hydrophilic interfacial tension, while the understanding of the synergistic mechanism is limited. In the present work, mixed monolayers of surfactin and branched alkylbenzene sulfonate at the n-decane/water interface were studied using atomistic molecular dynamics simulations, and the presence of surfactin affecting the microstructure and dynamic properties of the mixed monolayer was evaluated at molecular level. The density distributions of the surfactants along the direction normal to the interface, radial distribution functions of the surfactant head groups, hydrophobic contacts between surfactants, translational activities of both surfactants and counterions, and the dynamics of the hydrogen bonds formed between surfactant and water were calculated. The results suggested that the structure of the mixed monolayers was more compact than that of the individual system of alkylbenzene sulfonate and the interfacial tension was more efficiently reduced, and the translational activities of both surfactants within the mixed monolayers were much lower. The results implied that biosurfactant surfactin and alkylbenzene sulfonate mixed well at the n-decane/water interface, though they were both anionic surfactants.

中文翻译：

---

阴离子生物表面活性剂Surfactin与化学合成的阴离子表面活性剂烷基苯磺酸盐在正癸烷/水界面的混合

生物表面活性剂在降低疏水性/亲水性界面张力方面显示出与合成表面活性剂的协同作用，而对协同作用机理的理解是有限的。在目前的工作中，表面活性素和支链烷基苯磺酸盐的混合单层在n使用原子分子动力学模拟研究了癸烷/水的界面，并在分子水平上评价了表面活性素是否影响混合单层的微观结构和动力学性质。计算表面活性剂沿垂直于界面方向的密度分布，表面活性剂头基团的径向分布函数，表面活性剂之间的疏水接触，表面活性剂和抗衡离子的平移活性以及表面活性剂与水之间形成的氢键的动力学。结果表明，混合的单层结构比烷基苯磺酸盐的单个体系更致密，界面张力更有效地降低，并且两种表面活性剂在混合单层中的翻译活性要低得多。结果表明，生物表面活性剂表面活性剂和烷基苯磺酸盐在室温下混合良好。正癸烷/水界面，尽管它们都是阴离子表面活性剂。