Temperature effect on the AuNP-PE interfacial confinement and the underlying physics

FL Zhang and GT Wang and RJ Wang and LY Wang and J Xia and C Tang and CY Wang and WG Wu, COMPUTATIONAL MATERIALS SCIENCE, 258, 114070 (2025).

DOI: 10.1016/j.commatsci.2025.114070

The confinement effect at nanoparticle (NP)-polymer matrix interface is vital to the determination of nanocomposite functionalities and varies due to thermal modulation. Nevertheless, fundamental understanding of the nanoconfinement and temperature effect on it has yet to be clarified in terms of the impacts of the interfacial interaction and/or molecular mobility. Using molecular dynamics (MD) simulations and theoretical models we characterized the temperature-dependent mass density and chain orientation of polymer near a gold NP (AuNP)polyethylene (PE) interface. The interfacial van der Waals (vdW) interaction is found to generate compressive stress concentrations and local density peaks, which diminish with rising temperature due to the thermal expansion mismatch between AuNP and PE. Furthermore, it is established that the vdW interaction also exerts a rotational moment on polymer chain segments (PCSs) causing a trend of PCSs to orient parallel/perpendicular to the AuNP surface. This tendency is most pronounced at room temperature but diminishes with temperature deviations due to the molecular mobility changes. The study provides a theoretical framework for optimizing the nanocomposite properties by tailoring interfacial structures.

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