Changes in polarity and aggregation number upon clouding of a nonionic detergent: Effect of ionic surfactants and sodium chloride

The dehydration and aggregation behavior of Triton X-114 with increasing temperature were studied by using pyrene as fluorescent probe and N,N-dibutylaniline as a quencher. The effect of added NaCl, SDS, and CTAB in a 0.01 M TX-114 solution was investigated. Polarity studies indicated a gradual dehydration of the micelles with a rapid change at the cloud point. The presence of added electrolyte suppressed the dehydration process. The distribution of the fluorophore and the quencher among the micellar compartments resulted in both negative and positive deviations from the linear Stern-Volmer plot. The calculated aggregation numbers (N) indicated continuous micellar growth up to the cloud point, where micellar coalescence produced a sharp rise of N beyond the experimental limits.