Molecular Simulations of Adsorption of Surfactant Micelles on Partially and Fully Covered Iron Surfaces
Molecular Simulations of Adsorption of Surfactant Micelles on Partially and Fully Covered Iron Surfaces
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DOI：
10.1016/j.molliq.2023.121685
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发表时间：
2023-03
影响因子：
6
通讯作者：
Abolfazl Faeli Qadikolae;Sumit Sharma
中科院分区：
文献类型：
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作者：
Abolfazl Faeli Qadikolae;Sumit Sharma
表面活性剂-金属相互作用在诸如缓蚀和金属纳米颗粒合成等应用中非常重要，其中表面活性剂的添加通常超过其临界胶束浓度。在这些条件下，表面活性剂胶束与游离表面活性剂分子处于动态平衡状态。由于它们的扩散速度比胶束快，游离表面活性剂分子迅速吸附在金属-水界面上。因此，吸附表面活性剂胶束总是与某些吸附表面活性剂发生金属-水界面。我们通过原子模拟研究了季铵盐表面活性剂的胶束在部分或全部被表面活性剂分子吸附的铁-水界面上的吸附行为。我们发现，在部分覆盖的表面上，胶束倾向于吸附在裸露的金属片上。在完全覆盖的表面上，胶束吸附在已经被吸附的分子的顶部，并达到半球形形态。吸附自由能随表面活性剂对铁-水界面覆盖面积的增大而减小。
Surfactant – metal interactions are important in applications like corrosion inhibition and synthesis of metallic nanoparticles, wherein surfactants are often added above their critical micelle concentration. Under these conditions, surfactant micelles exist in dynamic equilibrium with free surfactant molecules. Due to their faster diffusion compared to the micelles, free surfactant molecules rapidly adsorb onto metal-water interfaces. Therefore, adsorbing surfactant micelles invariably encounter metal-water interfaces with some adsorbed surfactants. We have studied, via atomistic simulations, adsorption behavior of micelles of a quaternary ammonium-based surfactant at iron-water interfaces that are partially or fully covered with adsorbed surfactant molecules. We find that on a partially covered surface, a micelle prefers to adsorb on a bare metal patch. On a fully covered surface, the micelle adsorbs on top of already adsorbed molecules and attains a hemispherical morphology. The adsorption free energy decreases as the coverage of iron-water interface with surfactants increases.