非离子表面活性剂在气液界面的分子动力学模拟

• 作 者: 李晓锋 李应成 吴智勇 谢在库 范康年
• 机 构: 中石化上海石油化工研究院,上海,201208;复旦大学化学系,上海,200433
• 出 处: 化学学报
• 发表日期: 2011年19期
• 关键词: nonionic surfactant air/water interface molecular dynamics interfacial tension

采用分子动力学方法研究了十二烷基醇聚氧乙烯醚系列非离子表面活性剂单分子层在气液界面的微观结构,并通过表面张力的计算考察了表面活性剂分子结构与性能的关系.研究结果表明,随着表面活性剂分子乙氧基基团个数的增加,模拟所得的表面张力的变化趋势与实验一致,所有分子的计算误差在5 mN·m-1以内.同时,随着乙氧基基团数目的增加,所计算的表面活性剂分子亲水端的厚度逐渐增大,而憎水端的厚度则在乙氧基基团等于6时呈现最大值,这也与中子反射实验相吻合.另外,研究发现,与憎水端相比,表面活性剂的亲水端具有更大的倾斜角,即更倾向于与气液界面平行排列.“,”Molecular dynamics simulations have been carried out to study the microscopic properties of monolayer of monododecyl ethers of poly-oxyethylene glycol absorbed at the air/water interface.The struc-ture-behavior relationship was investigated through the calculation of the interfacial tension.The calculated interfacial tensions with the number of ethylene oxide groups agree well with the experimental data with the error within 5 mNom-1.The thickness of the hydrophilic parts increased as the increasing of ethylene oxide groups while there was the maximum thickness of hydrophobic parts with six ethylene oxide groups,which are also in good agreement with the neutron reflection experiments.It is also found that the hydrophilic parts are more tilted toward the plane of the interface compared to the hydrophobic parts.