A study of the interaction of dodecyl sulfobetaine with cationic and anionic surfactant in mixed micelles and monolayers at the air/water interface

The miscibility and interactions between components in mixed adsorbed films and micelles containing zwitterionic (dodecyl sulfobetaine-DSB) and cationic (dodecyltrimethylammonium bromide) or anionic (sodium dodecyl sulfonate) surfactant, respectively, have been investigated. The molecular interactions have been quantified by the values of the excess free energy of adsorption (ΔGS,Exc) and micelle formation (ΔGM,Exc). The obtained results indicate nonideal behavior of the investigated mixtures since the values of ΔGS,Exc and ΔGM,Exc are negative. Moreover, it has been found that DSB interact more strongly with anionic surfactant as compared to cationic surfactant owing to different structure of mixed monolayers and micelles.