We have been studying the solution interactions leading to formation of solid polymer-surfactant films at the air-solution interface. We wish to use the mesostructures in the films as hosts for polymerisation of hydrophobic monomers to make polymer nanostructures. Previously polymerisation of monomers in swollen micelles has destroyed the mesophase due to rapid diffusion of surfactant during the reaction. In our films the high viscosity of the hydrogel may prevent rearrangement of the micelles as polymerisation occurs. In this experiment we wish to study encapsulation of styrene and methyl methacrylate into cationic micelles in solution in the presence and absence of the film forming polymer polyethylenimine. SANS, using contrast variation will enable us to quantify encapsulation and location of the species in the micelles and to identify the effect of polymer on the solution structures.