Mixed micellization of binary alkanediyl-α,ω-bis(dimethyldodecylammonium bromide) homologues in aqueous solution

We report a systematic investigation on the mixed micellization of the binary homologues of Gemini surfactant 12-s-12 series that has a flexible polyethylene spacer. The results showed that the micellization behavior deviates from the ideality when the difference of the spacer lengths (Δs) of two components is larger than 6. The obvious synergism between two components occurs in the mixtures of 12-2-12/12-18-12 and 12-4-12/12-18-12. This was attributed to a relatively large difference in the molecular shape of the two components induced by the length and the configuration of the spacer chain, which yielded better steric compensation between two components within a mixed micelle than other mixed systems.