CO2/N2 triggered Switchable surfactants with imidazole group

Article abstract of DOI:10.1007/s11743-014-1569-2

In order to overcome the hydrolysis of 2-alkyl-1-hydroxyethyl imidazoline and its unsatisfactory emulsification-demulsification switchability to water-alkane, the long-chain N-alkylimidazole compounds were synthesized by n-octyl bromide, n-decyl bromide, n-dodecyl bromide, n-tetradecyl bromide and n-hexadecyl bromide with imidazole, respectively and characterized by MS, ¹H NMR and FTIR. The long-chain N-alkylimidazole compounds can be reversibly transformed into charged surfactants by exposure to CO₂. Surface tension values indicated that N-alkylimidazolium bicarbonates had excellent surface activity compared with corresponding conventional surfactants with a lower γ _CMC. The surface behaviors of the five surfactants can be illustrated by A _min. Five conductivity cycles by bubbling CO₂ and N₂ alternately indicated that these surfactants could be switched by CO₂ reversibly and repeatedly. Emulsions were repeatedly stabilized for five cycles by N-alkylimidazolium bicarbonate and broken by bubbling N₂ through the solutions to reverses the reaction, releasing CO₂.