分子内扭转电荷转移探针DMABN测定表面活性剂水溶液的临界胶团浓度

以对二甲氨基苯甲腈(DMABN)为探针, 测定它在表面活性剂(C12TABr、SDS、C12E23、C12-3-12·2Br)水溶液中的第二重荧光强度(Ia)和对应的特征波长(λa)对表面活性剂浓度(c)曲线, 由Ia-c 曲线的转折点或λa-c曲线对应的一阶导数极小点可以获得临界胶团浓度(cmc). 由于C12-3-C12·2Br在水溶液中强烈聚集, 利用λa-c曲线还可以获得其胶团结构松散度的信息.

Determination of the Critical Micelle Concentration of Surfactant in Aqueous Solution by Twisted Intramolecular Charge Transfer Probe DMABN

With p-N,N-dimethylaminobenzonitrile (DMABN) as a probe, the variations of the intensity of its second fluorescence emission (Ia) and the corresponding characteristic wavelength (λa) with the surfactant concentration (c), here the examined surfactants (C12TABr, SDS, C12E23, and C12-3-C12·2Br), were measured by Hitachi F4500 fluorescence spectrophotometer. The results showed that both the break point on the Ia-c curve and the minimum of the derivative variation corresponding to the λa-c curve agreed very well with the critical micelle concentration (cmc) of the surfactant in aqueous solution as measured by surface tension technique. Due to strong aggregation of C12-3-C12·2Br in aqueous solution, the information about loose micellar structure could be obtained by its λa-c curve.