Photophysical Processes in Polymers. V. Triplet Depletion in Solid Vinylnaphthalene Polymers and Copolymers

The results of a study of triplet energy trapping at 77°K are presented for vinylnaphthalene polymers and copolymers with styrene and methyl methacrylate. Delayed emission spectra originating from traps both intrinsic and extrinsic to the polymer chains are identified. In the solid polymers both intramolecular and interchain triplet energy migration occur, with eventual transfer to a trap at collisional distances of about 15 Å. Extrinsic traps lead to phosphorescence and delayed fluorescence, while traps that are part of the polymer chain lead to delayed exciplex fluorescence. In the model compound 1-ethylnaphthalene, only extrinsic trapping phenomena are observed. The influence of concentration on trapping phenomena in both polymers and the model compound is considered from the standpoint of chain or molecular aggregation.