Fluorescence study of polymer chain interpenetration and of the rate of phase separation in incompatible polymer blends

The application of fluorescence techniques has been demonstrated for the study of four polymer problems: (a) If two different polymers are labeled with donor and acceptor fluorophores, respectively, which exhibit nonradiative energy transfer, the emission spectrum of their blends will depend on whether the two polymeric species are miscible or segregated into separate phases. Thus, the emission spectrum may be used as a measure of polymer compatibility. (b) Since rapid freeze‐drying preserves the extent of chain interpenetration which existed in solution, the energy transfer between labeled polymers may be used to study the extent of such interpenetration on solution concentration. (c) Phase separation when heating blends of poly(methyl methacrylate) and poly(benzyl methacrylate) may be followed by the change in the emission spectrum of the latter. (d) The interdiffusion of separated poly(ethyl methacrylate) molecules labeled with donor and acceptor fluorophores may be monitored by the increase in the nonradiative energy transfer.