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 γCMC. The surface behaviors of the five surfactants can be illustrated by Amin. 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.