Synthesis, Characterization and Properties of N-Alkyl-N,N-di(2-hydroxyethyl) Amine Oxides

N -Dodecyl- N , N -di(2-hydroxyethyl) amine oxide (C 12 DHEAO) and N -stearyl- N , N -di(2-hydroxyethyl) amine oxide (C 18 DHEAO) were synthesized with N -alkyl-diethanolamine and hydrogen peroxide. Their chemical structures were confirmed using 1 H-NMR spectra, mass spectral fragmentation and FTIR spectroscopic analysis. It was found that C 12 DHEAO and C 18 DHEAO reduced the surface tension of water to a minimum value of approximately 28.75 mN m −1 at concentration of 2.48 × 10 −3 mol L −1 and 32.45 mN m −1 at concentration of 5.21 × 10 −5 mol L −1 , respectively. The minimum interfacial tension (IFT min ) and the dynamic interfacial tension (DIT) of oil–water system were measured. When C 18 DHEAO concentration was in the range of 0.1–0.5%, the IFT min between liquid paraffin and C 18 DHEAO solutions all reached the ultra-low interfacial tension. Furthermore, their foam properties were investigated by Ross-Miles method, and the height of foam of C 12 DHEAO was 183 mm. It was also found that they showed strong emulsifying power.