Mixed micelles of cationic gemini with tetraalkyl ammonium and phosphonium surfactants: the head group and hydrophobic tail contributions

The conductivity (κ) and Kraft temperature (KT) measurements were carried out for the binary combinations of dimeric cationic gemini, di(dodecyldimethylammonium bromide) (12-2-12), with alkyl phosphonium and ammonium bromide surfactants to evaluate the mixed micelle formation influenced by head group (i.e. dimeric and monomeric) and hydrophobic tail modifications (i.e. C12–C16). Both studies demonstrated that the dimeric bulky head group of 12-2-12 induced significant steric hindrances in the mixed micelle combinations with phosphonium surfactants as the length of latter’s hydrophobic tail exceeds that of 12-2-12. This effect was relatively less prominent with ammonium head group surfactants and almost vanished when instead of 12-2-12, DTAB was taken in combination with phosphonium surfactants.