Surface properties of cationic gemini surfactants and their interaction with alkylglucoside or -maltoside surfactants

The interaction of a series of cationic gemini surfactants (surfactants con taining two hydrophilic groups and hydrophobic groups in the molecule) with decyl-P-maltoside, decyl-P-glucoside, and dodecyl-P-maltoside at pH = 9 in 0.1 M NaCl at 25 degreesC has been investigated. The five cationic gemini surfactants are [C12H25(CH3)(2)N+(CH2)(4)N+(CH3)(2)C12K25]. 2Br(-) and [C10 H21(CH3)(2)N+-spacer-N+(CH3)(2)C10H21]. 2Br(-) with four different spacers: -(CH2)(4)-; -CH2CH(OH)CH(OH)CH2-; -CH2CH2OCH2CH2-; -CH2CH(OH)-CH2-. The re sults illustrate the effects of sterid and electrical factors on mixed mono layer and mixed micelle formation and of surfactant-surfactant interactions there. The cationic gemini surfactants and their mixtures with either the alkylmaltoside or the alkylglucoside show stronger interactions at the air/ water interface than comparable conventional cationic surfactants (with sin gle similar hydrophobic and hydrophilic groups) and a greater preference fo r adsorbing at the air/water interface relative to mixed micelle formation in the solution phase. Mixtures containing cationic geminis with hydrophobi c spacers showed packing contraction at the air/water interface; those with hydrophilic spacers, packing expansion. Interaction, both in mixed monolay er formation at the air/water interface and in mixed micelle formation in t he solution phase, is always stronger with the decyl glucoside than with de cyl maltoside. The decyl cationic gemini with smallest spacer shows stronge st interaction with the decyl glucosdie or maltoside at the air/water inter face and weakest interaction in mixed micelle formation.