Adsorption of gelatin in combination with sodium dodecyl sulfate or hexadecyltrimethylammonium bromide to a polystyrene/water interface

Neutron reflection has been used to measure the adsorption of gelatin, in combination with the surfactants sodium dodecyl sulfate and hexadecyltrimethylammonium bromide, to polystyrene. For gelatin/ surfactant systems, a mixed adsorbed layer is observed with a similar diffuse density profile to gelatin alone. The relative proportion of each component at the interface depends on the sequence of adsorption. Adsorption of a mixture to a fresh surface produces a layer with a high proportion of surfactant. Addition of gelatin or a gelatin/ surfactant mixture to an existing surfactant layer displaces surfactant from the interface. Adsorbed gelatin is not removed on addition of a surfactant solution; some surfactant penetrates, but the layer remains rich in gelatin. © Springer-Verlag 1999.