分子动力学模拟温度对CTAB/SA胶束结构的影响

Molecular Dynamics Simulation of the Effect of Temperature on the CTAB/SA Structure

采用分子动力学模拟研究了温度对于十六烷基溴化铵/水杨酸(CTAB/SA)酸性条件下聚集结构的影响.结果表明在高温和强酸条件下,CTAB/SA体系形成球形胶束.通过分析分子的均方根位移和径向分布函数等动力学性质,我们发现升高温度能够显著加剧分子运动.因此,CTA+和水杨酸分子之间的结合作用力减弱.特别是胶束周围的阴离子的扩散使得极性头基之间的互斥作用增强,因而在80℃和强酸条件下,胶束结构为球形胶束.模拟表明,分子动力学方法可以在分子水平上研究胶束体系,解释温度和酸碱度对于聚集性质影响的原因.

Molecular dynamics simulations were performed to study the effect of temperature on the aggregated structure for aqueous mixtures of a cationic surfactant （cetyltrimethylammonium bromide,CTAB） and salicylate acid （SA）,The spherical micelle was obtained at 80℃ and pH 0,which is in well agreement with the experimental researches,By analyzing the mean square displacement and radical distribution functions of the molecules in the micellar system,it can be concluded that higher temperature enhanced the molecular motion,The interactions between the surfactant and the salicylate molecules or Cl - ions weakened,Thus,the repulsion of the CTA ^＋ headgroups led to the breakage of the pre-assembled cylindrical micelle into spherical micelles,The simulations revealed an atomic-level insight into the mechanism of temperature induced shape transitions in the CTAB/SA systems,which was expected to provide useful information for the experimental researches,