The change in the properties of sodium dodecyl sulfate micelles upon addition of isomeric and unsaturated short-chain alcohols probed by photophysical methods

The properties of sodium dodecyl sulfate micelles (SDS) in the presence of I-propanol, 2-propanol, and 2-propen-1-ol (allyl alcohol) were investigated using electrical conductivity and fluorescence quenching methods. The constants of association of the alcohols to SDS micelles, obtained experimentally and calculated from linear solvation energy relationship analysis, are in the range 1-2 M-1, indicating that these additives behave not only as cosolvents but also as micellar surface active solutes. Larger molecular volume and lower basicity of the alcohol favor partitioning to the micelle. The formation of smaller micelles upon addition of the alcohols is accompanied by an enhancement of solute intermicellar migration and intramicellar quenching rate constants. In particular, the micelle fragmentation-coagulation process of the SDS (0.04 M)/allyl alcohol (1.5 M) system occurs in the time range of 1.5 mus, as indicated by the intermicellar exchange rate constant of the N-dodecylpyridinium ion. (C) 2001 Academic Press.