Polystyrene-MethyIcyclohexane Solutions Undergoing Phase Separation: A Study by Fluorescence Spectroscopy

John M. Torkelson, Matthew Tirrell, Curtis W. Frank

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The phase separation of 17 500 molecular weight polystyrene (PS)/methylcyclohexane solutions has been studied by fluorescence spectroscopy. In contrast to a previous report, the sensitivity to phase separation of the ratio of excimer to monomer fluorescence intensity, IE/IM was small, with a decrease observed in those regions occupied by the PS-lean phase after macroscopic phase layering and an increase observed in those regions occupied by the PS-rich phase after macroscopic phase layering. A polychromator was used to continuously monitor IE and IM during phase separation. The magnitude of the changes with time in IE IM compares favorably with those predicted by the two-phase model developed for PS/poly(vinyl methyl ether) phase separation by Gelles and Frank. For samples of critical composition, IE IM changed about 10-15% during phase separation for quenches of less than 0.7 K below the critical temperature, increasing steadily at long times in rich-phase regions while decreasing steadily at long times in lean-phase regions. At short times, IE IM variously increased and decreased, and the overall fluorescence intensity varied widely, depending upon the region of the sample cell being monitored. A sharp increase in IE IM with increasing PS content for PS volume fractions <0.04 was observed in miscible solutions near the critical temperature and may be due to coil contraction caused by the trend toward segregation or to increasing intermolecular interactions.

Original languageEnglish (US)
Pages (from-to)1505-1512
Number of pages8
Issue number8
StatePublished - Jan 1984

ASJC Scopus subject areas

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


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