Unexpected Molecular Weight Dependence of Dynamics in Polymer Nanocomposites

ORAL

Abstract

The impact of nanoscale confinement in polymer nanocomposites has invoked tremendous interest ever since the reports of dramatic changes in polymer dynamics with relatively low nanoparticle concentrations. It has been shown that the segmental dynamics at an attractive polymer/nanoparticle interface slows down significantly due to formation of an interfacial layer. The general expectation is that the length scale of this layer and its influence will grow with increasing polymer molecular weight (MW). Our measurements reveal an opposite trend: the magnitude of the effect on segmental dynamics decreases with increasing MW. Based on detailed analysis of dielectric spectroscopy and small angle x-ray scattering measurements we provide a qualitative explanation of the unexpected observation.

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Authors

  • Adam P. Holt

    University of Tennessee, Knoxville, Department of Physics and Astronomy, University of Tennessee, Knoxville, Department of Physics, University of Tennessee

  • Shiwang Cheng

    Department of Chemistry, University of Tennessee, Knoxville

  • Vera Bocharova

    Chemical Sciences Division, Oak Ridge National Laboratory

  • Philip Griffin

    University of Pennsylvania, Department of Materials Science and Engineering, University of Pennsylvania

  • Adam Imel

    Department of Chemistry, University of Tennessee, Knoxville

  • Mark Dadmun

    Department of Chemistry, University of Tennessee, Knoxville, University of Tennessee, Knoxville, University of Tennessee, Department of Chemistry, University of Tennessee; Chemical Sciences Division, Oak Ridge National Laboratory, Department of Chemistry, The University of Tennessee, Knoxville, TN and Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN

  • Alexei Sokolov

    Department of Chemistry, University of Tennessee, Knoxville, Chemical Sciences Division, Oak Ridge National Lab; Department of Physics and Astronomy, Department of Chemistry, University of Tennessee, Oak Ridge National Lab, Department of Chemistry, University of Tennessee; Chemical Sciences Division, Oak Ridge National Laboratory, University of Tennessee, Knoxville