Molecular interaction in binary surfactant mixtures containing alkyl polyglycoside

Surface tensions were measured for several binary mixtures of a multidegree polymerized alkyl polyglycoside, C12G1.46, with different types of surfactants in 0.1 M NaCl at 25 °C. Based on regular solution theory, using a dimensional crystal model and a phase separation model, the molecule exchange energy in mixed monolayer formation (ɛ) and mixed micellization (ɛm) were determined. Surfactants used in the mixtures with C12G1.46 in this study are C12E3S (trioxyethylenated dodecyl sulfonate), C12TAC (dodecyl trimethylammonium chloride), BE-6 (hexaoxyethylenated trisiloxane surfactant), and TMN-6 (hexaoxyethylenated-2,6,8-trimethylnonanol). The mixtures show exchange energy in mixed monolayer formation (ɛ) and mixed micellization (ɛm) ranging from −660 to −1410 J/mol, indicating a decrease in surface energy upon mixing. The decreases in surface energy are in the order C12G1.46/C12E3S > C12G1.46/C12TAC, C12G1.46/C12TAC > C12G2/C12TAC and C12G1.46/BE-6 > C12G1.46/TMN-6. The ability of the mixed monolayer formation relative to the mixed micelle formation of the same binary mixture, measured by the (ɛ−ɛm) values, is in the order C12G1.46/BE-6 > C12G1.46/TMN-6 > C12G1.46/C12E3S→0 > C12G1.46/C12TAC.