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

摘要

A number of techniques, including conductivity, surface tension, dynamic light scattering, transmission electron microscopy, and ~(1)H nuclear magnetic resonance (~(1)H NMR), Fourier transform infrared (FT-IR), and ~(1)H–~(1)H 2D nuclear Overhauser effect spectroscopy (~(1)H–~(1)H 2D NOESY), have been used to investigate the effect of amide bonds on the interfacial and assembly properties of a cationic surfactant, N -anilinoformylmethyl-N -cetyl-N ,N -dimethyl ammonium chloride (AMC-C _(16 )), in aqueous solutions. The adsorption of AMC-C _(16 ) has been found to be much better than that of the conventional cationic surfactant, benzyl cetyldimethylammonium chloride (BAC-16 ) at the air/water interface and in solution. The surface tension measurements show the presence of two critical aggregation concentrations (CAC_(1) and CAC_(2)) for AMC-C _(16 ). The presence of a strong intermolecular hydrogen bond of AMC-C _(16 ) was confirmed by ~(1)H NMR and FT-TR. The molecular interactions of AMC-C _(16 ) were detected by ~(1)H–~(1)H 2D NOESY. The results show that the rigid group (phenyl) of AMC-C _(16 ) was partially overlapped with its alkyl chain in aqueous solution, and the possible aggregation behavior for AMC-C _(16 ) was proposed. The effects of an inorganic salt (NaCl) and an organic salt (C_(6)H_(5)COONa) to the aggregates of AMC-C _(16 ) have been discussed.