稳态荧光探针法测定临界胶束聚集数

Determination of Critical Micellar Aggregation Numbers by Steady-state Fluorescence Probe Method

以芘为荧光探针、二苯甲酮为猝灭剂，用稳态荧光探针法测定了 SDS和 AS的胶束聚集数 (Nm).以芘的饱和水溶液为溶剂配制表面活性剂溶液，二苯甲酮的适宜浓度取小于 1.00 mmol· L－ 1时，可以获得满意的实验结果 .当表面活性剂溶液浓度为 5～ 9倍 cmc时， Nm随表面活性剂浓度增大而线性增大，而随温度的变化略有波动 .cSAA=cmc时， Nm值为一本征值，定义为临界胶束聚集数 [Nm].[Nm]值可从 Nm－ cSAA实验曲线外延得到 .25℃时 SDS的临界胶束聚集数 [Nm]为 57； 40℃时 SDS的 [Nm]为 49， AS的 [Nm]为 55.

Aggregation numbers of micelle (N-m) of SDS and AS were determined by steady-state fluorescence probe method in which pyrene was used as fluorescence probe and benzophenone as quencher. Satisfactory results were obtained as shown in Fig. 1 similar to2 when the solution of surfactant was prepared with a saturated aqueous solution of pyrene and the optimum concentration of benzophenone was selected in 0 similar to1.00 mmol L-1. The experimental results in Fig. 3 similar to5 and Table 4 show that when concentration of surfactant is in 5 similar to9 times of cmc, N-m increases linearly with the increase of concentration and fluctuats slightly with the increment of temperature. It is indicated that N-m is an eigenvalue at c = cmc, which has been defined here from as the critical micellar aggregation number [N-m].[N-m] can be extrapolated from N(m)similar toc(SAA) experimental curves, as shown in Table 3 for SDS 57 (25 degreesC) and 49 (40 degreesC) and for AS 55 (40 degreesC), respectively.