Abstract: Three novel rosin-based Gemini surfactants, i.e., 1, 6-bis(3-dehydroabietic amide-propyl-dimethyl ammonium bromide)hexane, 1, 8-bis(3-dehydroabietic amide-propyl-dimethyl ammonium bromide)octane and 1, 10-bis(3-Dehydroabietic amide-propyl-dimethyl ammonium bromide) decane (abbreviated to R-6-R, R-8-R and R-10-R), were synthesized from dehydroabietic acid via reactions of amidation and quaternization.The surface activities of three surfactants were investigated by surface tension and electric conductivity methods.And the results showed that the critical micelle concentrations (C_cmc) of R-6-R, R-8-R and R-10-R were 0.41, 0.39 and 0.24 mmol/L, and the minimum molecular occupation areas (A_min) were 1.00, 1.46 and 1.72 nm², respectively.The amide groups in the hydrophobic chain promoted the adsorption of surfactants at the interface.The presence of a rigid rosin skeleton made this kind of surfactants have strong foam stability and emulsifying properties.The foam half-lives of R-6-R, R-8-R and R-10-R were 1 320, 1 200 and 1 050 min, respectively.And the emulsion remained stable after 7 days when the concentration of surfactant was only 0.3 mmol/L.

Key words: dehydroabietic acid, rosin-based Gemini surfactant, foam, emulsion