Mixed Micelles of Triton X-100 and Cetyl Trimethylammonium Bromide in Aqueous Solution Studied by ¹H NMR

Abstract

1H NMR chemical shift, spin−lattice relaxation time, spin−spin relaxation time, and two-dimensional nuclear Overhauser enhancement (2D NOESY) measurements show that Triton X-100 (TX-100) molecules coaggregate with cetyl trimethylammonium bromide (CTAB) molecules in aqueous solutions. The concentration of TX-100 in the mixed solutions of this study is 3 mM, with varying molar ratios of CTAB/TX-100 (C/T) ranging from 0.5 to 2.9. The results give information about the structure of the mixed micelles. The α-methylene group of CTAB is in the near vicinity of the phenoxy ring of TX-100. The trimethyl group attached to the polar head of CTAB locates between the first oxyethylene group next to the phenoxy ring of TX-100, and the end methyl group of CTAB is close to those of TX-100. The closely packed (coiled) hydrophilic polyoxyethylene chains in the exterior part of the mixed micelles gradually extend with an increase in C/T in the mixed solution. CTAB and TX-100 molecules are uniformly mixed in the micelles in each mixed solution.

The effect of water on the microstructure and properties of benzene/[bmim][AOT]/[bmim][BF4] microemulsions

“…The microstructure and structural changes of the IL-based microemulsion can be outlined by 2D NMR to a certain extent although it is difficult to determine the precise interproton distances between each individual proton from the cross-peak intensities of the ROESY spectrum. 59 The variations of ROESY spectra of the [bmim] [BF 4 ]-in-benzene microemulsion with water content are shown in Fig. 10.…”

Mixed Micelles of Polyethylene Glycol (23) Lauryl Ether with Ionic Surfactants Studied by Proton 1D and 2D NMR

“…Thus, compared with the CTAB/TX-100 system, we can find a marked difference in conformational change of the hydrophilic poly oxyethylene chain in the coaggregation of CTAB with the nonionic surfactants of different hydrophilic chain lengths. The effect of steric hindrance exerted by the trimethyl groups of CTAB can cause the relatively shorter hydrophilic poly oxyethylene chains (8-9 oxyethylene units) to extend in the mixed micelle with the increase in CTAB content, as in the case of the CTAB/TX-100 system (17), whereas the conformation of the long poly oxyethylene chains (23 oxyethylene units) remain coiled, but looser in the mixed micelles with the increase of C/B, as in the case of the CTAB/Brij-35 mixed system.…”

“…The structure and dynamic properties of their self-aggregated micelles have been thoroughly studied by various methods, including 1 H NMR measurements (11)(12)(13)(14)(15)(16). By the use of the 1D and 2D NMR techniques we have recently shown (17) that the α-methylene group of CTAB is located in the near vicinity of the phenoxy ring of the nonionic surfactant, Triton X-100 (TX-100), in their mixed micelles, and the end methyl group of CTAB is close to those of TX-100. Furthermore, the closely packed (coiled) hydrophilic polyethylene chains in the exterior part of the mixed micelles gradually extend with an increase in the CTAB component in the mixed solution, whereas the mixing of TX-100 with the anionic surfactant, SDS, does not show this effect (18).…”

1H NMR Study of Mixed Micellization of Sodium Dodecyl Sulfate and Triton X-100

“…These facts indicate that the hydrophilic chains of TX-100 molecules are coiled under these conditions, and the conformation of the hydrophilic polyoxyethylene chains of the SDS/TX-100 mixed micelles is very similar to that of the self-aggregated TX-100 micelles in an aqueous solution. In contrast to the case of the CTAB/TX-100 mixed system (20), the intensity of these cross peaks does not decrease with an increase in molar ratio (S/T). This implies that the conformations of the hydrophilic polyoxyethylene chains of TX-100 remained unchanged during the mixing of TX-100 with different amounts of SDS.…”

“…Only a few studies are relative to properties of TX-100 mixed micelles (10,14,19). Recently, we have found that cetyltrimethylammonium bromide (CTAB) and TX-100 molecules are uniformly arranged in the mixed micellar core with the polar head of CTAB situated between the first ethoxy groups next to the phenoxy rings of TX-100 (20). The interaction of sodium dodecyl sulfate (SDS)/TX-100 mixed micelles with polyelectrolytes, such as polydimethyldiallylammonium chloride (PDADMAC), has been extensively studied by numerous spectroscopic and hydrodynamic methods (21)(22)(23)(24).…”