During the dissolution process, polymer in the glassy state is, transported into a dilute solution. In some cases, a transition layer can be measured using laser interferometry. This layer is seen as a difference in reflected light intensity between the bare substrate and the maximum during dissolution. When poly(methyl methacrylate) dissolves in methyl ethyl ketone, the layer is not detectable below a polymer number‐average molecular weight of about 30,000. The layer becomes more pronounced as molecular weight of polymer increases.

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