Early stages of polymer interdiffusion.
We have examined the wavelength dependence of the diffusion coefficient in a multilayer deuterated polystyrene-hydrogenated polystyrene system. The measurements were performed using neutron reflectivity. The decay of the Bragg peak was also followed in great detail. The measured wavelength diffusion coefficient D(k) was also not found spatially dependent on the distance of the diffusional couples to the substrate. On the basis of our results, it was possible to reconstruct the broadening interface of polymer bilayer sample geometry which had characteristics of a diffuse tail and a sharp core.