Fluorescence Study of Aggregation Behaviour of Cationic Surfactant Carbethopendecinium Bromide and its Comparison with Cetyltrimethylammonium Bromide

The aggregation behaviour of the cationic surfactant carbethopendecinium bromide (Septonex) and cetyltrimethylammonium bromide (CTAB) in aqueous solution was investigated by steady-state and time-resolved fluorescence experiments. Values of critical micelle concentration were obtained from the pyrene emission polarity index. The micellar aggregation numbers for four different concentrations of both surfactants were determined by steady-state and time-resolved fluorescence quenching methods, using pyrene as a probe and cetylpyridinium chloride as a quencher. The results obtained for Septonex were compared with the aggregation parameters of CTAB. Generally, Septonex micelles were formed by a smaller number of surfactant monomers than in the case of CTAB and the critical micelle concentration of Septonex is lower than that of CTAB. Also, the concentration dependence of the micelle aggregation number was found.