H-1 NMR study of mixed micellization of sodium dodecyl sulfate and Triton X-100

The two-dimensional nuclear Overhauser enhancement spectroscopy (2D NOESY), H-1 NMR chemical shift, and spin-lattice and spin-spin relaxation measurem ents of aqueous solution of various molar ratios of sodium dodecyl sulfate (SDS) to Triton X-100 (TX-100) from 0.27 to 8.0 give some detailed structur e of the mixed micelles formed. The appearance of cross peaks between the p rotons of SDS and those of TX-100 in the 2D NOESY map is direct evidence fo r the solubilization of the hydrocarbon chains of SDS inside the TX-100 mic elles that have nonextended hydrocarbon chains. The effect of the aromatic ring currents of TX-100 on the protons of the methylene groups, which are n earest to the polar head of SDS, indicates the near vicinity of these group s. The existence of the cross peaks between the hydrophilic protons and the remote hydrophobic protons of TX-100 suggests that the hydrophilic chains are not extended in the mixed micelles. 1H spin-lattice relaxation time (T- 1) and spin-spin relaxation time (T-2) measurements support the results obt ained by the 2D NOESY experiments. (C) 2001 Academic Press.