新型甜菜碱型两性离子表面活性剂界面行为的分子动力学模拟

摘要

利用分子动力学模拟方法研究了新型系列甜菜碱型两性离子表面活性剂在辛烷-水体系的界面行为.结果表明,分子动力学模拟得到的该体系油-水界面张力值与实验值相符,可以定性比较不同分子结构的甜菜碱型表面活性剂降低油-水界面张力的能力；不同温度下烷烃-水-甜菜碱型表面活性剂体系的油-水界面张力变化不大,具有良好的耐温性；加入不同量NaCl时,该体系的油-水界面张力保持稳定,表明甜菜碱型表面活性剂具有良好的抗盐能力.在分子层面上探讨表面活性剂构效关系对油-水界面张力的影响,可为三次采油中驱油用表面活性剂的筛选提供理论依据.%The behavior of betaine zwitterionic surfactants in the interface of octane+water system was investigated by molecular dynamics simulation. The simulated oil-water interfacial tension value was consistent with the experimental value, which could be used to qualitatively compare the ability of oil-water interfacial tension reduction of betaine surfactants with different molecular structures. The oil-water interfacial tension of octane + water + betaine surfactant system changed little with the increase of temperature, meaning that the system hold good heat resistance. Meanwhile, the oil-water interfacial tension of octane+water + betaine surfactant system remained stable as different amount of NaCl added, indicating that the betaine surfactants had good salt tolerance. Researching the effect of the structure-activity relationship in surfactant on oil-water interfacial tension at the molecular level could provide the theoretical basis for surfactant screening in tertiary oil.