双子表面活性剂的结构与性质间关系的研究

Studies on the correlation between structure and properties of surfactant

采用量子化学和分子力学方法优化了双子表面活性剂阳离子的几何构型 ,得到了轨道能级、生成焓和弯曲能等数据。计算结果表明 :随着联结基团长度 (s)增大 ,最高占据分子轨道能级 (EHOMO)和最低空轨道能级 (ELUMO)依次升高 ,且两者能级差 (△E)也依次增大。用量子化学方法计算的与按键焓加和规则计算的这些阳离子的生成焓之差随联结基团长度增大而迅速增大。分析发现 ,这些现象与极性头两个氮原子之间C -C键的平均键长 ( RC -C)有关 ,经拟合 ,相关系数为 0 945。同时还讨论了弯曲能与形成胶束的标准自由能变化 (△Gmin)之间的关系。

The orbital energies,Δ fH m ? and bend energies of the molecules [C 12 H 25 N(CH 3) 2(CH 2) sN(CH 3) 2C 12 H 25 ] 2+ (GM 2+ )(s=2～12)were obtained.The calculated results show that:as the S increases,E HOMO and E LUMO increase,and ΔE(E LUMO -E HOMO )increase,too.It is found that the difference Δ(Δ fH m ?)of Δ fH m ?(AM1)for GM 2+ calculated by AM1 and Δ fH m ?(SUM)the sum of bond energies methods increases speedily when s increases,which relates to the average bond length C-C of the C-C bonds between two N + of the polar head group of GM 2+ .The correlation coefficient of the Δ(Δ fH m ?)and the C-C is 0 945.The relation between the bend energy and the ΔG mic formed micelle are discussed.