Pyrene-tagged polymers, fluorescence

Pvrene Fluorescence Spectra. Solutions of the tagged polymers In diglyme were prepared to have 1 x 10 M pyrene, based on the tagging levels mentioned in the previous section. This resulted in polymer concentrations of 2.33 x 10, 8.47 x 10, 3.65 x 10, 1.99 x... 

Figure 5. Fluorescence spectra of pyrene tagged novolac and free pyrene butyric acid (PBA) in diglyme. Spectra are labeled with percent of monomer units tagged. The pyrene concentration in solution is 1 x 10 bM, except in the inset where different pyrene concentrations are compared along with the spectra of a film containing the tagged polymer.

Excimer to Monomer Intensity Ratio. Our approach toward the determination of this information is to focus on the configurational behavior of the pyrene-terminated PEG. Two sets of experiments were performed to separate the intramolecular behavior of the isolated Py-PEG-Py chains from the intermolecular interactions that occur between labeled PEG chains. First, we performed photostationary fluorescence measurements of IJI for fully labeled PEG as a function of the molar ratio of the poly(carboxylic acid) to that of the PEG. These results will contain both intermolecular and intramolecular contributions to the excimer fluorescence. Next, we performed analogous measurements with the same total amount of PEG but with only 1% having pyrene labels. The selection of the relative amount of the tagged polymer is somewhat arbitrary, but it appears to be sufficiently low to provide a reasonable approximation to the behavior of the isolated, labeled PEG chain. These fluorescence results are then subtracted from those for the fully tagged system, leaving just the intermolecular contribution. 

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