High-pressure effects on the order-disorder transition in block copolymer melts

Damian A. Hajduk, Sol M. Gruner, Shyamsunder Erramilli, Richard Alan Register, Lewis J. Fetters

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

We have measured the pressure dependence of the order-disorder transition temperature (TODT) in two styrene-isoprene diblock copolymers containing 24 and 48 wt % styrene (Mw = 20 500 and 16 500 g mol-1, respectively). Small-angle X-ray scattering measurements indicate that TODT rises linearly with increasing hydrostatic pressure in both systems at a rate of +20°C kbar-1 (approximately) over the range from 0 to 600 bar; deviations from linearity appear at higher pressures. This increase is approximately twice the value that we have previously estimated from measurements of changes in polymer characteristics with high pressure.1 We present dilatometric measurements across the ODT which show a volume change (ΔV/V) of order +5 × 10-4 upon disordering. The observation of a change in specific volume at the ODT has implications for experimental and theoretical investigations of polymer phase behavior, which we discuss. Finally, we demonstrate the existence of pressure-induced ("barotropic") phase transitions in these materials and compare their characteristics with those of the analogous temperature-induced ("thermotropic") transitions.

Original languageEnglish (US)
Pages (from-to)1473-1481
Number of pages9
JournalMacromolecules
Volume29
Issue number5
DOIs
StatePublished - Feb 26 1996

All Science Journal Classification (ASJC) codes

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

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