Molecular simulations of adsorption self-assembly of SDS surfactants on nano-sized multilayer graphenes

doi:10.11949/j.issn.0438-1157.20150050

Abstract

Abstract:

Molecular dynamics simulations were carried out to study the structure and morphology of SDS adsorbed on nano-sized graphene surfaces in pure water and electrolyte solution. The effects of the layer numbers of the graphene on the adsorption self-assembly structure and the buoyant density of the SDS/graphene assemblies were explored. The simulation results show that the aggregate morphology was highly dependent on the layer number of the graphene in both solutions. The stretching of surfactants to solution was enhanced with increasing layer number, leading to expansion of the self-assembly structure. In the presence of electrolyte in the solution, the surfactant micelles of SDS were transformed from the rough multi-layer to hemi-cylinder structure. In the meantime, the buoyant densities of the SDS/graphene assemblies were found to increase linearly with increasing layer number of the graphene. This behavior provided a direct theoretical basis for graphene dispersion with controlled thickness using the density gradient ultracentrifugation in the surfactant aqueous solution.

Key words: graphenes, surfactants, adsorption self-assembly, dispersion, molecular simulation

摘要：

采用分子动力学模拟分别研究了纯水和电解质溶液中SDS表面活性剂在纳米尺度石墨烯表面的自组装结构,考察了不同石墨烯层数对自组装吸附形态和SDS/石墨烯复合物悬浮密度的影响。模拟结果揭示了上述两种溶剂介质中,SDS的表面自组装结构形态与石墨烯的结构层数有关,增加石墨烯的层数能够加大吸附表面活性剂向溶液中的伸展程度,使表面活性剂自组装结构膨胀。此外电解质存在能够导致SDS表面活性剂在石墨烯表面吸附形态由多层结构向半圆胶束转化。模拟计算进一步发现SDS/石墨烯超分子复合物的悬浮密度随石墨烯层数的增加呈近似线性增加。

关键词: 石墨烯, 表面活性剂, 吸附自组装, 分散, 分子模拟

CLC Number:

TQ015

LIU Shuyan, CHEN Qi, WU Bin, YANG Xiaoning. Molecular simulations of adsorption self-assembly of SDS surfactants on nano-sized multilayer graphenes[J]. CIESC Journal, 2015, 66(7): 2709-2717.

刘淑延, 陈琦, 吴彬, 杨晓宁. SDS表面活性剂在纳米尺度多层石墨烯的吸附自组装分子模拟[J]. 化工学报, 2015, 66(7): 2709-2717.

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