Abstract
Diffusion-limited interactions between benzil and anthracene were studied by phosphorescence quenching in polystyrene-cyclohexane, polystyrene-toluene, poly(methyl methacrylate)-toluene, and polybutadiene-cyclohexane solutions. Values of the bimolecular diffusion-limited quenching rate constant, kq, were obtained by measuring benzil phosphorescence lifetime as a function of anthracene concentration and applying a Stern-Volmer analysis. Besides polymer species and solvent, kqwas measured as a function of polymer molecular weight and concentration, up to 560 g/L. kqwas found to be independent of polymer molecular weight in polystyrene-cyclohexane solutions and exhibited a slight molecular weight dependence in polystyrene-toluene solutions. The polymer concentration dependence of kqin polystyrene-cyclohexane and polystyrene-toluene solutions was found to mimic the polymer concentration dependence of the solvent self-diffusion coefficient; this result is consistent with the notion that kq~ DS/DS0where Dsis the solvent self-diffusion coefficient and the subscript 0 indicates the value at zero polymer concentration. A very similar polymer concentration dependence of kqwas obtained in poly(methyl methacrylate)-toluene solutions. The Vrentas-Duda free volume theory for DSwas found to predict the polymer concentration dependence of kqquantitatively for polystyrene-toluene and approximately for poly(methyl methacrylate)-toluene solutions; over the range of polymer concentrations studied in polystyrene-cyclohexane solutions, the agreement between the Vrentas-Duda theory and experimental measures of kqappears to be less satisfactory. The Fujita-Doolittle theory can also be used to fit experimental measures of kqin selected cases; however, it is possible to obtain unphysical results if the Fujita-Doolittle theory is applied over too wide a range in polymer concentration.
Original language | English (US) |
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Pages (from-to) | 1033-1041 |
Number of pages | 9 |
Journal | Macromolecules |
Volume | 21 |
Issue number | 4 |
DOIs | |
State | Published - 1988 |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry