中文摘要：

合成出具有不同头基尺寸的季铵盐Gemini表面活性剂C12（n）-4-C12（n）·2Br（n=1,2,3时分别对应甲基、乙基和丙基,即四亚甲基-α,ω-二（十二烷基二甲（乙、丙）基溴化铵））.以稀释法研究C12（n）-4-C12（n）·2Br在庚烷中形成的W/O微乳的组成和结构.结果表明,庚烷溶液中的部分己醇参与构成混合界面膜,从而改善了混合组分的分子几何形状,生成了稳定的W/O微乳.随着水含量W0增大,微乳的水核也随之增大,变小的界面曲率减小了混合膜对己醇量的需求.增大C12（n）-4-C12（n）·2Br头基尺寸,界面层中己醇与表面活性剂的摩尔比（a）先增大（n从1到2）然后再减小（n从2到3）.W0愈大,a在n从2到3时减小得愈明显.在W0=10和20时,微乳水核半径Rw随n增大而减小;但在W0=30时,当n从2到3,Rw反倒明显增大.这些结果表明,季铵头基相连的两个丙基其行为与相连两个甲基或两个乙基时不同,这两个丙基弯曲朝向庚烷,撑大了表面活性剂烷烃链区域的体积,致使混合界面膜上己醇分子的需求量减少,有助于形成较大尺寸的水核.

英文摘要：

Butanediyl-α,ω-bis-（dialkyldodecyl-ammonium bromides） （alkyl = methyl, ethyl, and propyl）, which referred to as C12（n）-4-C12（n）·2Br（n=1,2,3）, had been synthesized. The results studied by dilution method showed that a part of n-hexanol in n-heptane together with surfactant constructed a mixed film, which improved the molecular geometry of the mixed components and resulted in the formation of W/O microemulsion. The size of the water pool enlarged with increasing water content W0, which decreased the surface curvature of the water pool and therefore reduced the requirement for n-hexanol in the mixed film. With increasing the head-group size of C12（n）-4-C12（n）·2Br, i.e. n from 1 to 2, the mole ratio of n-hexanol at the film to surfactant a increased, and then decreased with further increasing n from 2 to 3. At W0=10 and 20, the radius of water pool Rw reduced with increasing n, but at W0=30, Rw increased considerably with increasing n from 2 to 3. These results indicated that the propyl groups linked with quaternary ammonium behaved differently from linked methyl or ethyl groups. The propyl groups may bend toward the bulk n-heptane. This unfurled the volume of the alkyl chain region of surfactant and thus decreased the requirement for n-hexanol in the film, which favored to form large water pool.