中文摘要：

用量子化学中的密度泛函理论,在B3LYP/6-31＋G＊水平上,对十二烷基磺基甜菜碱分子进行了结构优化,在分子水平上研究了两性表面活性剂与阳离子（Ca2＋）、阴离子（Cl-）之间的相互作用.计算结果表明：两性表面活性剂的负电荷中心采用2∶1型,即极性头中两个氧原子与阳离子发生稳定结合;而正电荷中心采用侧方,即N原子的两个亚甲基和一个甲基与阴离子发生稳定结合.由于桥联亚甲基和α-亚甲基均带有一定数量的电荷,因此两性表面活性剂中正负电荷中心需要根据亚甲基上电荷多少进行划分.计算也发现,表面活性剂尾链带有部分弱电荷,使胶束内核带有了部分极性,利于表面活性剂在溶液中的聚集,此种极性介于烷烃油相和水相的极性之间.

英文摘要：

The structure of zwitterionic surfactant sulfobetaine,i.e.N-dodecyl-N,N-dimethyl-3-ammonio1-propanesulfonate,was optimized using density functional theory（DFT） at the B3LYP/6-31＋g（d） level and the interactions between the surfactant and Ca2＋ or Cl-ions were studied at the molecular level.The results showed that： i） a 2∶1 type pair between zwitterionic negative center（SO3-） and Ca2＋ was formed,in which two oxygen atoms of the polar group（SO3-） in the surfactant bound with one Ca2＋ ion;ii） the positive center（—N＋（CH3）2—） bound with one Cl-through two methyl groups and one methylene which connect to N atom.Since there are some weak charges on the methylene nearest to the polar groups,the negative and positive centers in the polar group of surfactant should be re-divided.The calculation also showed that the tail chain has a weak charge resulting in the core of the micelle having polarity.This core polarity of the micelle is somewhere between the oil phase polarity and the water phase polarity,which fa-vors surfactant aggregation in solution.