The impact of fragility on the properties of the glass formation of polymer nanoparticle composites

ORAL

Abstract

We investigate the effects of nanoparticles on glass formation in a model polymer melt by molecular dynamics simulations. The addition of nanoparticles allows us to change the relaxation time, glass transition temperature $T_g$, the fragility of glass formation in a controlled fashion. We show that the structural relaxation for different temperatures, concentrations, and polymer-NP concentrations can be expressed in terms of a simple universal function of the short-time Debye-Waller factor. We further examine how the stretching exponent $\beta$ and the degree of the breakdown of the Stokes-Einstein relation depend upon fragility, which we relate to the extent of cooperative motion.

*JFD acknowledges support from NIH grant 1 R01 EB006398- 01A1. BAPB and FWS acknowledge support from NSF grant number CNS-0959856 and ACS-PRF grant 51983-ND7

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Authors

  • Beatriz A. Pazmino Betancourt

    • Physics Dept., Wesleyan University, Middletown, CT

  • Jack Douglas

    • Materials Science and Engineering Division, NIST, Gaithersburg, MD
    • NIST, Gaithersburg, MD
    • Polymer Division, NIST, Gaithersburg, MD
    • The National Institute of Standards and Technology
    • Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA

  • Francis Starr

    • Wesleyan University, Middletown CT
    • Physics Dept., Wesleyan University, Middletown, CT
    • Department of Physics, Wesleyan University, Middletown, CT 06459, USA