分子内电荷转移荧光探针法测定表面活性剂的临界胶束浓度

研究了分子内电荷转移荧光体4-二甲氨基查尔酮(DMAC)在表面活性剂水溶液中的荧光光谱。观察到随表面活性剂浓度增大,DMAC 的荧光光谱先红移然后蓝移,而荧光强度呈“S”型变化并于光谱位移方向转折处突跃。突跃处对应的表面活性剂浓度即为其临界胶束浓度(cmc)。结果表明由该法测定的 cmc 与已报道值符合,说明方法的可行性与准确性。用该法测定表面活性剂/β-环糊精混合体系的 cmc,表明β-环糊精的存在诱导了胶束的形成。

Determination of Critical Micelle Concentration of Surfactant by Using An Intramolecular—Charge—Transfer Fluorescence Probe

The fluorescence spectra of 4-dimethylaminochalcone(DMAC),an intramolecular- charge-transfer fluorescence probe,are examined as a function of surfactant concentration in aqueous solution.It is observed that the fluorescence spectrum shifts to red,at first,and then to blue with increasing surfactant concentration and a break aqqears in the curve of fluorescence in- tensity with surfactant concentration at the point where the spectral shifting direction turns over.The critical micelle concentration(cmc)of the surfactant is obtained from this break point in a good agreement with the reported value.The measurement of the cmc's in the CTAB/β-cy- clodextrin systems has indicated the β-CD induced micellarization of CTAB in aqueous solution, which is in agreement with the reported conclusion.