不同结构头基对阴/非离子表面活性剂混合体系胶团化行为的影响

Effect of Different Head Group Structures on Micellization Behavior of Anionic/Nonionic Surfactant Systems

摘要:

通过表面张力法和荧光探针法研究了含有不同反离子的阴离子表面活性剂十二烷基硫酸钠(NaDS)、十二烷基硫酸镁(Mg(DS)2)分别与头基结构不同的非离子表面活性剂n-十二烷基-β-D-麦芽糖苷(DDM)、十二烷基聚四氧乙烯醚(Brij30)组成的二元混合体系的协同作用以及胶束性质。结果表明，各混合体系均存在较强的协同效应，且协同效应强弱顺序为：Mg(DS)2/DDM＜NaDS/DDM＜Mg(DS)2/Brij30＜NaDS/Brij30。Mg(DS)2与非离子之间的吸引作用较NaDS的弱，Mg2+使MDS偏离标准值程度小于Na+。利用Maeda模型得到的相互作用结果与Rubingh理论所得结果一致。此外，相对于具有刚性头基结构的DDM，具有易弯曲柔性头基结构的Brij30更能促进混合胶束形成，反离子对混合体系的胶束聚集数和微极性影响较小。

Abstract:

The micellization behavior of binary surfactant mixtures containing anionic surfactants with different counter ions viz. sodium dodecyl sulphate (NaDS)and magnesium dodecyl sulphate (Mg(DS)2) and nonionic surfactants with different head group structures viz. n-dodecyl-β-D-maltoside (DDM) and dodecyl tetraethylene glycol ether (Brij30) in aqueous solution were investigated respectively by surface tension and fluorescence probe methods. The results indicated that strong synergistic effect exist between the two components of micelles of all the mixed surfactant systems. The magnitude of synergistic effect followed the order Mg(DS)2/DDM＜NaDS/DDM＜Mg(DS)2/Brij30＜NaDS/Brij30. Mg(DS)2 had less interaction with nonionic surfactants in comparison to NaDS. Mg2+ leaded to MDS in mixed micelle was less far away from the standard state compare with Na+ 。The results of the interaction between surfactants and the contribution of free energy by Maeda’s model were consistent with that of Rubingh’s theory. Moreover, nonionic surfactant with the flexible head group encourages the formation of the mixed micelle and counter ions have little great impact on the aggregation and micropolarity of mixed surfactant systems.