Interface and Interphase in Polymer Nanocomposites with Bare and Core-Shell Gold Nanoparticles.

Albert J Power,Ioannis N Remediakis,Vagelis Harmandaris

doi:10.3390/polym13040541

Albert J Power, Ioannis N Remediakis + Show 1 more

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https://doi.org/10.3390/polym13040541

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Abstract

Metal nanoparticles are used to modify/enhance the properties of a polymer matrix for a broad range of applications in bio-nanotechnology. Here, we study the properties of polymer/gold nanoparticle (NP) nanocomposites through atomistic molecular dynamics, MD, simulations. We probe the structural, conformational and dynamical properties of polymer chains at the vicinity of a gold (Au) NP and a functionalized (core/shell) Au NP, and compare them against the behavior of bulk polyethylene (PE). The bare Au NPs were constructed via a systematic methodology starting from ab-initio calculations and an atomistic Wulff construction algorithm resulting in the crystal shape with the minimum surface energy. For the functionalized NPs the interactions between gold atoms and chemically adsorbed functional groups change their shape. As a model polymer matrix we consider polyethylene of different molecular lengths, from the oligomer to unentangled Rouse like systems. The PE/Au interaction is parametrized via DFT calculations. By computing the different properties the concept of the interface, and the interphase as well, in polymer nanocomposites with metal NPs are critically examined. Results concerning polymer density profiles, bond order parameter, segmental and terminal dynamics show clearly that the size of the interface/interphase, depends on the actual property under study. In addition, the anchored polymeric chains change the behavior/properties, and especially the chain density profile and the dynamics, of the polymer chain at the vicinity of the Au NP.

Highlights

The study of polymer-based hybrid materials is a field of immense interest as it involves a broad spectrum of systems, applications, and spatiotemporal scales
From the broad family of polymer nanocomposites (PNCs) here we focus on systems with metal nanoparticles (NPs)
We study via atomistic simulations polymer nanocomposites with bare and grafted Au NPs; the latter were constructed in their minimum energy configuration, via the Wulff method, whereas the PE/Au interaction is derived via density functional theory (DFT) calculations

Summary

Introduction

The study of polymer-based hybrid materials is a field of immense interest as it involves a broad spectrum of systems, applications, and spatiotemporal scales. On polymer/solid nanostructured systems in particular, the solid phase can strongly modify the properties of the entire hybrid system, such as its mechanical and electrical ones, as well as its dynamical/rheological behavior [1,2,3,4,5,6,7]. The investigation of model polymer/solid interfacial systems, at the molecular level, is an intense research area, since such interfaces play a crucial role on the behavior of polymer-based systems with important technological applications, including for example polymer nanocomposites, polymer coatings, lubricants and thin films [8,9,10,11,12]. The improvement of the tensile strengths of nanocomposite films [16] and the enhancement of the interfacial adhesion between nanoparticle and polymer matrix are very important [17]. Nanoparticles modify the mechanical properties of a polymer matrix [18,19]

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