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从微观机理上研究表面活性剂对微乳胶粒形成的影响有利于推动微乳状液在各个领域的应用研究.本文采用分子动力学模拟方法研究了微乳胶粒的形成过程及表面活性剂对微乳胶粒形成的影响.正十二烷(C12H26)和十二烷基硫酸钠(SDS)作为油分子和表面活性剂分子的模型,Martini粗粒化(coarse-grained,CG)力场描述分子间和分子内的相互作用,对含有不同浓度的正十二烷和表面活性剂的12个模型分别进行了100 ns的分子动力学模拟.模拟结果显示,不含表面活性剂的体系迅速发生水油相分离,且分离过程伴随着势能的明显下降;含有表面活性剂的体系中,在相同时间内通过模拟得到了稳定的、表面活性剂分子包裹油分子的胶粒.对不同温度下模拟得到的数据分析发现,胶粒形成初期的动力学特征可以近似地表达为二级反应,聚集活化能为14.6 kJ/mol.
The study of the effect of surfactant on the formation of micro-emulsion particles from the micro-mechanism is conducive to promoting the application of micro-emulsion in various fields.In this paper, the molecular dynamics simulation method was used to study the formation of micro-emulsion particles and the effect of surfactant on the micro-emulsion (C12H26) and sodium dodecyl sulfate (SDS) as models of oil molecules and surfactant molecules, Martini’s coarse-grained (CG) force field describes the intermolecular and Molecular interactions, 12 models with different concentrations of n-dodecane and surfactant were respectively subjected to 100 ns molecular dynamics simulations. The simulation results show that the surfactant-free system rapidly undergoes water-oil phase Separation, and the separation process accompanied by a significant decline in potential energy; surfactant containing system at the same time by simulation obtained a stable, surfactant molecules encapsulated oil molecule particles. Simulated data at different temperatures It was found that the kinetic characteristics of the initial micelle formation can be expressed as a second order reaction with an activation energy of 14.6 kJ / mol.