Macromolecules with Tunable Fluorescence via Photochemical Step-Growth Polymerization

We introduce a class of macromolecules whose emission can be modulated by changing the ratio of monomer to excimer fluorescence. The change in fluorescence emission can be finely adapted by altering the number of pyrene units in the polymer backbone, with the density of the pyrene units dictating the intensity of the excimer emission relative to the monomer emission. The fluorescent polymers are prepared via photochemical Diels–Alder step growth polymerization of a bifunctional o-methyl benzaldehyde monomer and a bismaleimide-based pyrene containing a pyrene-free monomer. We carefully evidence the polymer chain structure across different polymer compositions and demonstrate that the excimer emission strength is controllable based on the monomer ratios within the polymer chain. The strength of our approach lies in its ability to produce uniquely emitting polymers using a straightforward synthetic process.