NEUTRON REFLECTION FROM MIXTURES OF SODIUM DODECYL-SULFATE AND DODECYL BETAINE ADSORBED AT THE HYDROPHOBIC SOLID AQUEOUS INTERFACE/

The technique of specular neutron reflection has been used to study th e structure and composition of single and mixed surfactant layers adso rbed from aqueous solution onto self-assembled monolayers of octadecyl trichlorosilane on silicon oxide, The surfactants used were the anion ic sodium n-dodecyl sulfate and the zwitterionic n-dodecyl-N,N-dimethy lamino acetate and all measurements were made at the critical micelle concentration of the system, Molecular areas for the single surfactant s were found to be similar to those measured at the air/solution inter face and to those measured at the glycerol trioleate/solution interfac e, The structure and composition of the mixed surfactant layers are al so similar to those obtained at the air/solution interface, The two su rfactants mix at the solid/liquid interface in a highly nonideal and s pecific manner. (C) 1997 Academic Press.