Polymerizable Cationic Gemini Surfactant

A polymerizable cationic gemini surfactant, [CH2C(CH3)COO(CH2)11N+CH3)2CH2]2·2Br-, 1has been synthesized and its basic interfacial properties were investigated (in water and in the presence of 0.05 M NaBr). For comparison, the properties of monomeric surfactant corresponding to 1, CH2C(CH3)COO(CH2)11N+(CH3)3·Br-, 2, were also investigated. Parameters studied include cmc (critical micelle concentration), C20 (required to reduce the surface tension of the solvent by 20 mN/m), γcmc (the surface tension at the cmc), Γcmc (the maximum surface excess concentration at the air/water interface), Amin (the minimum area per surfacatant molecule at the air/water interface), and cmc/C20 ratio (a measure of the tendency to form micelles relative to adsorb at the air/water interface). For the polymerizable gemini surfactant, 1, the methacryloxy groups at the terminal of each hydrophobic group in a molecule have no contact with the air/water interface in the monolayer, whereas for the corresponding monomeric surfactant, 2, the methacryloxy group contacts at the interface forming a looped configuration like a bolaamphiphile. Polymerized micelles of the gemini surfactant are fairly small monodisperse and spherical particles with a mean diameter of 3 nm.