Synthesis and characterization of a series of amidine-based switch surfactants: toward environmental surface-active materials

A series of newly structured two-tailed cationic surfactants were synthesized via a carbonyl amine condensation reaction aimed at reducing the bioaccumulation of conventional surfactants while maintaining their excellent surface properties. Long-chain alkyl amine compounds can be reversibly converted into charged surfactants through CO2/H2O treatment and an alkyl chain length of between C8 and C12. The structures were characterized by IR,1H NMR and 13C NMR. The main surface activity parameters of the surfactants, containing cmc, γcmc pC20, cmc/С20, Γm and Αmin, were determined. The switching properties of N’-alkyl-N, N-dimethylalkamidine bicarbonate and N, N-dimethyl-N-alkylamidine bicarbonate were demonstrated by investigating their conductivities in solution and carrying out their emulsification-emulsion-breaking experiment.