Diffusion-Limited Phosphorescence Quenching Interactions in Polymer Solutions: Small Molecule-Small Molecule Interactions Interpreted by Free Volume Theory

Daniel H.S. Yu, John M. Torkelson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

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 languageEnglish (US)
Pages (from-to)1033-1041
Number of pages9
JournalMacromolecules
Volume21
Issue number4
DOIs
StatePublished - 1988

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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