CO₂/N₂ Triggered Switchable Surfactants with Imidazole Group

Abstract

Abstract 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, 1 H NMR and FTIR. The long‐chain N ‐alkylimidazole compounds can be reversibly transformed into charged surfactants by exposure to CO 2 . 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 CO 2 and N 2 alternately indicated that these surfactants could be switched by CO 2 reversibly and repeatedly. Emulsions were repeatedly stabilized for five cycles by N ‐alkylimidazolium bicarbonate and broken by bubbling N 2 through the solutions to reverses the reaction, releasing CO 2 .