| eutron reflection has recently gained wide acceptance as a tool to probe the one-dimensional depth profile of polymer layers: by selective deuteration of polymer molecules, the resulting contrast for neutrons is large enough to measure density variations at the interface with a resolution of 10 A. Using neutron reflection we have measured the interfacial profile in an extensive series of bilayered systems of protonated and deuterated polystyrene, and followed their evolution in time. Interdiffusion was achieved by annealing the bilayers above their glass temperature for specific periods of time. The results span over six decades of reduced annealing time; from the time characteristic of the segmental motion up to and beyond the time in which the molecules have diffused by their own length, the reptation time... |
