The Interfacial Zone in Thin Polymer Films and Around Nanoparticles in Polymer Nanocomposites
Jack F. Douglas, Wengang Zhang, Hamed Emamy, Fernando Vargas-Lara, Beatriz Betancourt, Francis W. Starr
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.
Journal of Chemical Physics
nanocomposite, polymer, interfacial zone, density gradient, mobility gradient, relaxation
, Zhang, W.
, Emamy, H.
, Vargas-Lara, F.
, Betancourt, B.
and Starr, F.
The Interfacial Zone in Thin Polymer Films and Around Nanoparticles in Polymer Nanocomposites, Journal of Chemical Physics
(Accessed December 1, 2021)