Mixed micellar properties of nonionic saccharide and anionic fluorocarbon surfactants in aqueous solution

Mixed micellar properties of nonionic saccharides (n-decyllactobionamide, C(10)Glu(2); n-dodecyllactobionamide, C(12)Glu(2)) and anionic fluorocarbon surfactants (lithium perfluorooctanesulfonate, LiFOS) in aqueous solutions have been studied by means of surface tensiometry, NMR, and light scattering. The interaction parameters estimated from the modified regular solution theory are -5.0 for the C(10)Glu(2)/LiFOS system and -0.2 for the C(12)Glu(2)/LiFOS system. This difference could be due to the interaction of the surfactant tails. The average aggregation number is almost identical over a wide mole fraction of C(12)Glu(2) for the C(12)Glu(2)/LiFOS system, while it shows a minimum at a C(10)Glu(2) mole fraction of 0.4 for the C(10)Glu(2)/LiFOS system. It is also found from NMR measurements that the segmental motions of surfactants in the mixed micelles of C(12)Glu(2) and LiFOS are not restricted, whereas they are restricted at a C(10)Glu(2) mole fraction of 0.4 for the C(10)Glu(2)/LiFOS system. These motional changes as well as micellar composition reflect the solubilization of decafluorobiphenyl in the mixed micelles. (C) 1998 Academic Press.