Time-resolved fluorescence quenching studies of sodium lauryl ether sulfate micelles

Journal of the Brazilian Chemical Society

Leidi C. Friedrich²  Volnir O. Silva²  Paulo F. Moreira Jr¹  Celize M. Tcacenco¹  Frank H. Quina² 

[1] ,Universidade de São Paulo Instituto de Química São Paulo SP ,Brazil

关键词: time-resolved fluorescence;    micelles;    detergents;    aggregation number;   

DOI  :  10.5935/0103-5053.20130031

来源: SciELO

【 摘 要 】

Aggregation numbers (N Ag) of micelles of the commercial anionic detergent sodium lauryl ether sulfate (SLES), with an average of two ethylene oxide subunits, were determined at 30 and 40º C by the time-resolved fluorescence quenching method with pyrene as the fluorescent probe and the N-hexadecylpyridinium ion as the quencher. The added-salt dependent growth of SLES micelles (γ = 0.11-0.15, where γ is the slope of a plot of log aggregation number vs. log [Yaq] and [Yaq] is the sodium counterion concentration free in the intermicellar aqueous phase) is found to be significantly lower than that of sodium alkyl sulfate micelles (γ ca. 0.25), a difference attributed to the larger headgroup size of SLES. The I1/I3 vibronic intensity ratio and the rate constant for intramicellar quenching of pyrene show that the pyrene solubilization microenvironment and the intramicellar microviscosity are insensitive to micelle size or the presence of added salt.

【 授权许可】

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