Adsorption of gelatin and sodium dodecyl sulphate to polystyrene

Neutron reflection experiments have been conducted on the adsorption of gelatin to polystyrene, and the effect of sodium dodecyl sulphate (SDS) on the adsorbed layer. The substrate for adsorption was a silicon crystal spun-coated with a film of polystyrene. This was placed in contact with different concentrations of gelatin solution between 0.0001% and 0.5% by weight, and reflectivity profiles obtained at 35 degrees C Rinsing the gelatin layer with water was found to remove some material from the surface of the layer, but not significantly change the composition. The addition of SDS solutions decreased both the thickness and composition of the gelatin layer. The most applicable model for the combined system was found to be gelatin and SDS combined in a single layer with exponential profile.