直链型非离子表面活性剂在油水界面吸附的动态Monte Carlo模拟

用动态Monte Carlo方法模拟了对称性和非对称性直链非离子表面活性剂在油水界面的吸附过程，得到了关于系统达到平衡所需要的时间、界面上吸附的表面活性剂分子数、界面层厚度、系统链节密度分布、油水界面张力等动态和静态信息，讨论了表面活性剂分子的结构和浓度对它们的影响;系统达到平衡所需要的时间与表面活性剂分子的结构和浓度有关，表面活性剂分子结构一定时，系统处于临界胶束浓度（CMC）以下时，平衡时间随浓度增加而增加;表面活性剂分子数目一定，平衡时间与表面活性剂的链长和结构有关;达到平衡以后，系统的链节密度分布关于油水分界面的对称性与表面活性剂分子的对称性有关;直链型非离子表面活性剂的表面活性主要由其结构决定，对于对称性的非离子表面活性剂，链越长表面活性越高，而对于非对称非离子表面活性剂，其对称性越高，表面活性越高;在链长一定的情况下，油水界面张力随着表面活性剂分子浓度的增加而增加，在达到一个稳定值后，不再随着浓度改变而改变.

Dynamic lattice Monte Carlo simulation of adsorption of nonionic-surfactants on oil-water interface

Dynamic lattice Monte Carlo simulation was used to study the adsorption of symmetric and unsymmetric nonionic-surfactants at the water-oil interface.The time needed to reach equilibrium,the numbers of the surfactant on the interface, the thickness of the interface between water and oil phases, the density distribution of segments A and B in the system and the interfacial tension,both static and dynamic were obtained and the effect of the structure and concentration of the nonionic-surfactants on these properties was studied too.The time needed for the system to reach equilibrium was related to the structure and concentration of the nonionic-surfactant.For the nonionic-surfactant with the same structure,the time increased when concentration of the surfactant increased under the situation that the concentration was below CMC.The time was determined by the length and structure of the chain when the number concentration was same.The symmetry of the density distribution curve of segments A and B was related to the composition of the nonionic-surfactant.The surface activity of nonionic-surfactant was decided by its structure mainly.For symmetric nonionic-surfactant, it was more active as its length increases.For unsymmetrical one, it was determined by the structure; The interfacial tension decreased as the concentration of the nonionic-surfactant increased and would not change when it reached a stable value when the length of the nonionic-surfactant is same.