Abstract: The dependence of the size and composition of sodium dodecyl sulfonate(AS) micclls on n-pentanol,n-hexanol and n-heptanol has been investigated using the steady-state fluorescence quenching technique. The results show that with the increase of alcohol concentration ([A]) at certain concentration of AS, the average aggregation number (N₁) of the mixed alcohol-AS micells decreases to a minimum and then increases with[A], but their average molecular number (N_A) increases steadily with [A].The hydrophobic radius of the spherical mixed pentanol-AS, hexanol-AS micells (R_m) has a minimum value on the plot of R_m versus X_A^m. The longer the alcohol chain the more pronounced this effect.

Key words: alcohol-sodium dodecyl sulfonate micell, hydrophobic radius, fluorescence quenching technique