Abstract: Aggregation numbers of micelle of citric triester of tridodecyl triammonium (CTTTA) were determined by steady-state fluorescence probe method in which pyrene was used as fluorescence probe and cetylpyridinium chloride (CPC) as quencher. Satisfactory results were obtained when the solution of surfactant was prepared with saturated aqueous solution of pyrene and the concentrations of CPC were selected in 0.1~0.3 mmol·L-1. The experimental results show that the aggregation number (N) increases linearly with the increase of CTTTA concentra-tion in the range of 6~10 times of cmc and critical micellar aggregation number Nm can be extrapolated from N－c curve. Critical micelle concentration (cmc) was investigated by steady-state fluorescence probe and compared with surface tentsion method.

Key words: Quaternary trimeric surfactant, Fluorescence probe, Aggregation number of micelle