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The Interfacial Zone in Thin Polymer Films and Around Nanoparticles in Polymer Nanocomposites

Published

Author(s)

Jack F. Douglas, Wengang Zhang, Hamed Emamy, Fernando Vargas-Lara, Beatriz Betancourt, Francis W. Starr

Abstract

We perform coarse-grained simulations of model unentangled polymer materials to quantify the range over which interfaces alter the structure and dynamics in the vicinity of the interface. We study both model polymer-nanoparticle (NP) composites with variable NP diameter, and thin supported polymer films, which have interfaces at the substrate and free surface of the film. The interfaces alter both the segmental packing and mobility in an interfacial zone near the interface. Variable NP size allows us to gain insight into the effect of boundary curvature, where the film is the limit of zero curvature. We find that the scale for perturbations of the density is relatively small and decreases on cooling for all cases. In other words, the interfaces before more sharply defined on cooling, as would be naively expected. In contrast, the interfacial mobility scale ξ for both NPs and supported films increases on cooling, and is on the order of a few nanometers, regardless of the polymer interfacial interaction strength. Additionally, the dynamical interfacial scale of the film substrate is consistent with a limiting value for polymer-NP composites as NP size grows. These findings are based a simple quantitative model to describe the distance dependence of relaxation that should be applicable to many interfacial polymer materials.
Citation
Journal of Chemical Physics

Keywords

nanocomposite, polymer, interfacial zone, density gradient, mobility gradient, relaxation

Citation

Douglas, J. , Zhang, W. , Emamy, H. , Vargas-Lara, F. , Betancourt, B. and Starr, F. (2019), The Interfacial Zone in Thin Polymer Films and Around Nanoparticles in Polymer Nanocomposites, Journal of Chemical Physics (Accessed December 1, 2021)
Created September 26, 2019, Updated April 24, 2020