物理化学学报 >> 2010, Vol. 26 >> Issue (03): 727-734.doi: 10.3866/PKU.WHXB20100309

量子化学及计算化学 上一篇    下一篇

烷基芳基磺酸盐的分子动力学模拟与自由能微扰计算

丁伟, 刘国宇, 于涛, 曲广淼, 程杰成, 吴军政   

  1. 大庆石油学院化学化工学院, 黑龙江 大庆 163318; 大庆油田有限责任公司科技发展部, 黑龙江 大庆 163453
  • 收稿日期:2009-09-28 修回日期:2009-12-30 发布日期:2010-03-03
  • 通讯作者: 丁伟 E-mail:dingwei40@126.com

Molecular Dynamics Simulations and Free Energy Perturbation Calculations of Alkyl Aryl Sulfonate

DING Wei, LIU Guo-Yu, YU Tao, QU Guang-Miao, CHENG Jie-Cheng, WU Jun-Zheng   

  1. College of Chemistry and Chemical Engineening, Daqing Petroleum Institute, Daqing 163318, Heilongjiang Province, P. R. China; Development Department of Science and Technology, Daqing Oil field Corp. Ltd., Daqing 163453, Heilongjiang Province, P. R. China
  • Received:2009-09-28 Revised:2009-12-30 Published:2010-03-03
  • Contact: DING Wei E-mail:dingwei40@126.com

摘要:

为研究不同结构的表面活性剂分子在溶液中胶束化能力的差异, 采用分子动力学方法模拟三种烷基芳基磺酸盐在真空和水溶液环境下的结构与相互作用. 利用自由能微扰(FEP)方法计算了水合自由能, 发现与用传统热力学表面张力法测定自制的烷基芳基磺酸盐结果一致. 研究表明: 烷基芳基磺酸盐在水溶液中的胶束化过程是自发进行的, 随着分子结构中芳环向长烷基链中间位置移动, 胶束化能力和胶束稳定性均下降; 疏水基周围水分子的“冰山结构”会影响胶束的稳定性, 而水分子中氢键的生存周期是反映冰山结构变化的重要指标; 同时, 亲水基与水分子间形成氢键的数目会增强或减弱分子脱离胶束体的趋势, 从而影响胶束结构的稳定性.

关键词: 分子动力学模拟, 烷基芳基磺酸盐, 胶束化, 水合自由能

Abstract:

To investigate the influence of surfactant molecular structure on micellization in solution, we used molecular dynamics to simulate the molecular structure and interaction of three alkyl aryl sulfonates in vacuum and in solution. The solvation free energy was calculated from the free energy perturbation (FEP) method and the obtained result was consistent with that obtained using the surface tension method. Research has shown that the micellization of alkyl aryl sulfonates in an aqueous solution is a spontaneous process as the aromatic ring shifts from the edge to the center of long carbonic chains, which results in a decrease in the ability of micelles to form and a decrease in their stability. Changes in the “iceberg structure”around the hydrophobic groups and the water molecules may affect the stability of the micelles and we studied the “iceberg structure”by considering the lifetime of the hydrogen bonds. Additionally, we find that the number of hydrogen bonds between the hydrophilic groups of the alkyl aryl sulfonates and the water molecules can affect the decomposition and stability of the micelles.

Key words: Molecular dynamics simulation, Alkyl aryl sulfonates, Micelle, Solvation free energy

MSC2000: 

  • O641