Secondary Dynamics in Ultrastable Polystyrene Thin Films Studied by β-NMR

ORAL

Abstract

Ultrastable, highly mono-disperse polystyrene (PS) thin films can be produced by physical vapor deposition. These films can exhibit properties similar to those of a normal glass that has been aged for thousands of years. β-detected nuclear magnetic resonance (β-NMR) of implanted 8Li+ probes can be used to study dynamics in thin polymer films, which is not possible with conventional magnetic resonance techniques [I. McKenzie et al. Soft Matter 14, 7324 (2018)]. We have used β-NMR to study the temperature dependence of the secondary γ-relaxation process in an ultrastable PS film and a normal PS film that was produced by rejuvenating an ultrastable film by heating to Tg+25 K for 2 minutes. The γ-relaxation is ~38% slower at 295 K, and the activation energy is ~20% larger in the ultrastable glass compared with the normal glass. Our interpretation of the results is that the denser packing in the ultrastable glass hinders motion of the phenyl rings.

*We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC).

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Presenters

  • Derek Fujimoto

    • University of British Columbia
    • Physics and Astronomy, University of British Columbia

Authors

  • Iain McKenzie

    • TRIUMF

  • Danaan Cordoni-Jordan

    • Chemistry, Simon Fraser University

  • Derek Fujimoto

    • University of British Columbia
    • Physics and Astronomy, University of British Columbia

  • Victoria L. Karner

    • University of British Columbia
    • Chemistry, University of British Columbia

  • Robert F Kiefl

    • University of British Columbia
    • Physics and Astronomy, University of British Columbia

  • Philip C. P. Levy

    • TRIUMF
    • University of British Columbia

  • W Andrew MacFarlane

    • University of British Columbia
    • Chemistry, University of British Columbia

  • Ryan M. L. McFadden

    • University of British Columbia
    • Chemistry, University of British Columbia

  • Gerald Morris

    • TRIUMF

  • Matt Pearson

    • TRIUMF

  • Adam Raegen

    • Physics and Astronomy, University of Waterloo

  • John Ticknor

    • University of British Columbia
    • Chemistry, University of British Columbia

  • James A Forrest

    • Physics and Astronomy, University of Waterloo
    • University of Waterloo