Evidence for a sharp interface between partially miscible polymers from a study by neutron specular reflection

The use of the specular reflection of neutrons to study the nature of the interface between the partially miscible polymers poly(methyl methacrylate) (PMMA) and solution-chlorinated polytehylene (SCPE) is reported. The upper, PMMA, layer has an increasing density gradient towards the surface, and after short annealing times the density of the PMMA increases. Further annealing causes a swelling of the SCPE by the PMMA and diffusion occurs predominantly on the SCPE side of the interface. The PMMA/SCPE interface moves toward the PMMA side but the width of the interface remains approximately constant. (author)