Achieving an Optimal Tg Change by Elucidating the Polymer–Nanoparticle Interface: A Molecular Dynamics Simulation Study of the Poly(vinyl alcohol)–Silica Nanocomposite System

Abstract

The glass transition temperature (Tg) of a polymer-nanoparticle-composite system is strongly dependent on the local segmental dynamics of the polymers. These dynamics, in turn, are dependent on the types of interfacial interactions that exist between the nanoparticle and the polymers. In this work, we investigate the magnitude of Tg-change with respect to the polymer-nanoparticle interactions by performing molecular dynamics simulations for a full-atomistic model of PVA-Silica nanocomposite. Our segmental dynamics analysis and potential of mean force calculations indicate that the strong binding interactions between hydroxylated-silica surface and the poly(vinyl alcohol) (PVA) are able to induce an increase in the Tg of the composite system with respect to the bulk PVA polymer system. While we expect that the Tg of the system will increase with an increasing amount of hydrogen bonds arising from the increasing surface hydroxylation, the trend of increasing Tg reaches a maximum when the surface is about 75...