An NMR Study on Two Mixed Micelles Formed by Nonionic Surfactants

Abstract

NMR techniques were used to study the relative arrangement and interaction sites in mixed micelles formed in NP-10/Tween40 and NP-10/C10E6 aqueous solutions. The results of two-dimensional NOESY experiments and relaxation time measurements showed that the interaction site of these two pairs of mixed surfactants were similar, but the intermolecular interaction between NP-10 and Tween40 was stronger than that between NP-10 and C10E6. T2 measurements demonstrated that inter-heteromolecular interactions decreased when the molar concentrations of Tween40 and C10E6 were larger than 2 and 4 folds of that of NP-10, respectively. Under such circumstances, the inter-homomolecular interactions began to play a key role, indicative of the ideal mixture molar ratio and the change of synergistic effect in the complex systems. T2/T1 ratio measurements indicated that molecular chain movement in the NP-10/Tween40 mixture was more limited than that in the NP-10/C10E6 mixture. The above conclusions were verified by spatial distance measurements.

Keywords

• NMR
• Tween40
• C10E6
• NP-10
• mixed micelles
• interaction
• dynamic change