Structure, Dynamics, and Apparent Glass Transition of Stereoregular Poly(methyl methacrylate)/Graphene Interfaces through Atomistic Simulations

Abstract

We provide a detailed investigation of the structure and dynamics of stereoregular poly(methyl methacrylate) (PMMA) chains confined between graphene layers via atomistic molecular dynamics simulations. The density, conformation, and interfacial segmental dynamics of low molecular weight isotactic, syndiotactic, and atactic PMMA chains are examined at various temperatures, ranging from 490 K up to 580 K. For all stereoisomers, a tendency of chains to adsorb on graphene via ester-methyl groups is observed. Compared to other stereoisomers, isotactic chains are stretched and form better organized layers at the interface. Concerning dynamical properties, various dynamical modes of PMMA are studied as a function of distance from graphene as well as over the entire confined system. The interfacial backbone and ester side group motions are restricted, whereas the fast motion of methyl groups remains unaffected. In the temperature range studied here, the interphase thickness remains almost constant; however, the r...