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Polymer Chemistry Research

Polymer Chemistry Research

The Effect of the Polymer-Solvent Conformational Interactions on the Formation of Pyrene Excimers

An excited pyrene molecule can form an excited dimer (excimer) with another pyrene molecule if the two molecules are close enough to each other. By attaching pyrene molecules to the ends of a polymer, the interactions between the polymer and solvent can be examined. A polymer in solution tends to become coiled with the extent of coiling depending on the solvent used. A “good” solvent causes less coiling than a “bad” solvent. A more coiled polymer would on average bring the two ends of the polymer closer together which would allow for or increase the amount of excimer formation. Fluorescence of pyrene, and the excimer, is observed, but both molecules do not fluoresce at the same wavelength. The dimer fluoresces at a higher wavelength because the energy of the dimer is lower than that of two pyrene molecules separated by the same distance.