Study on the Surface Properties and Aggregation Behavior of Quaternary Ammonium Surfactants with Amide Bonds.

A number of techniques, including conductivity, surface tension, dynamic light scattering, transmission electron microscopy, and H nuclear magnetic resonance (H NMR), Fourier transform infrared (FT-IR), and H-H 2D nuclear Overhauser effect spectroscopy (H-H 2D NOESY), have been used to investigate the effect of amide bonds on the interfacial and assembly properties of a cationic surfactant, -anilinoformylmethyl--cetyl-,-dimethyl ammonium chloride ( ), in aqueous solutions. The adsorption of has been found to be much better than that of the conventional cationic surfactant, benzyl cetyldimethylammonium chloride () at the air/water interface and in solution. The surface tension measurements show the presence of two critical aggregation concentrations (CAC and CAC) for . The presence of a strong intermolecular hydrogen bond of was confirmed by H NMR and FT-TR. The molecular interactions of were detected by H-H 2D NOESY. The results show that the rigid group (phenyl) of was partially overlapped with its alkyl chain in aqueous solution, and the possible aggregation behavior for was proposed. The effects of an inorganic salt (NaCl) and an organic salt (CHCOONa) to the aggregates of have been discussed.