Phase Separation of Oligomeric Polystyrene-Polybutadiene Blends As Studied by Excimer Fluorescence

Fu Jya Tsai, John M Torkelson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

The binodal curve and phase separation behavior of 826 MW polystyrene (PS)/2500 MW polybutadiene (PB) blends have been studied by optical density measurements and fluorescence spectroscopy, respectively. The equilibrium compositions from the binodal curve and the Gelles-Frank two-phase model, which relates the composition of phases generated during spinodal decomposition to the ratio of excimer to monomer fluorescence intensity, IE/IM, were used to follow the time-dependent compositions of the phases during phase separations as well as the kinetics of phase separation. For 30 wt % and 60 wt % PS blends quenched at 32 °C, the change in IE/IMduring phase separation was quite small, less than 10%, but nevertheless large enough to yield precise information. Cahn's theory of spinodal decomposition apparently describes adequately at least the first 3 min of phase separation, and the Gelles-Frank two-phase model predicts quantitatively IE/IMatequilibrium. Fluorescence results for the 30 wt % blend indicate that equilibrium is achieved in about 60 min; on the basis of the composition of the PS-rich phase the phase separation is about 90% complete in the first 13min. From the measured growth rate of decomposition, the Cahn-Hilliard diffusion coefficient is estimated to be of theorder -10-12cm2/s for both the 30 and 60 wt % PS/PB blends.

Original languageEnglish (US)
Pages (from-to)1026-1033
Number of pages8
JournalMacromolecules
Volume21
Issue number4
DOIs
StatePublished - Jan 1 1988

ASJC Scopus subject areas

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

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