低碳醇对季铵盐二聚表面活性剂C12-2-C12·2Br胶团化行为的影响

随着丙、丁、戊、已醇的加入,与季铵盐二聚表面活性剂C_(12)-2-C_(12)· 2Br组成了混合胶团,醇分子以烷烃链插入胶团中,羟基则位于胶团栅栏层处。这 减弱了表面活性剂离子头基间的静电排斥力,使临界胶团浓度(cmc)降低,同时使 胶团表面反离子解离度增大。随着醇分子的烷烃链增长,这种影响更为显著。

Effects of Alcohol on the Micellization of Quaternary-ammonium Dimeric Surfactant C12-2-C12@ 2Br in Aqueous Solution

The effects of n-propanol, n-butanol, n-pentanol and n-hexanol on the micellization of quaternary-ammonium dimeric surfactant C_(12)-2- C_(12)·2Br have been investigated using conductivity and steady fluorescence measurements. The results show that the surfactant and the alcohols form mixed micelles with addition of alcohols. In the mixed micelles, the alkyl chains of the alcohol molecules penetrate into the micelle interior and the hydroxyl groups lie in the palisade layer of the micelles, which weaken the electrostatic repulsion between the ionic head groups of the surfactants and result in a decrease of cmc and an increase of the ionization degree of the micelle. The effects become more striking with increasing the alkyl chain length of the alcohol molecules.