Movement of Polymer Segments by Exciplex Emission of Pyrene and N,N-Dimethylaniline at the Polymer–Silica Interface

Intermolecular interaction between pyrenyl units linked on the silica surface and N,N-dimethylaniline (DMA) units of polymer segments coated on the silica was investigated. Exciplex emission between these units was observed. The spectral shape and the intensity of the exciplex emission depended on the sample preparative conditions. Emission decay curves had no rise components, which showed that preformed ground-state complexes between pyrene and DMA existed and there were various microenvironmental sites around the preformed complexes just after sample preparation. Annealing of the samples made the exciplex emission wavelength shift and its intensity increase, which meant that polymer segments that contacted with the silica surface moved to make the stable conformations during annealing. It was revealed that DMA units of polymer segments are more stable when they face to the polymer–silica interface than when they become part of the polymer bulk. After the samples were kept at room temperature for 1 month, the spectra of all the samples became the same, which showed that the most stable conformations of the polymer segments were at the polymer–silica interface.