Synthesis of Novel Zwitterionic Heterogemini Surfactants Derived from Fatty Acid and Investigation of Their Behavior at the Air-Water Interface

A series of novel cationic–non-ionic heterogemini surfactants (Cn-1EC-s-Cm where n and m represents the hydrocarbon chain length of fatty acid and aliphatic amine, n=12, 14, 16, 18, m=12, 14, 16) were synthesized from fatty acid, epichlorohydrin and aldciphatic amine. The chemicals tructures of the surfactants were characterized by IR spectra, NMR, ESI-MS and elemental analysis. Their critical micelle concentrations (CMC) in the aqueous solutions were determined by surface-tension at 25°C.Relationship between γcmc and hydrophobic chain length was established which showed a large increase upon increasing of chain length with ester. The surface-tension measurements ofCn-1EC-s-Cm showed a low CMC, which greatly improve the efficiency in lowering the surface tension. Furthermore, adsorption and micellization behavior of Cn-1EC-s-Cm were investigated by measuring minimum average area per surfactant molecule and standard free energy.