Understanding the influence of configurations and intermolecular interaction on thermomechanical and dynamics properties of polymer-clay nanocomposites via molecular dynamics simulations

Polymer-clay nanocomposites (PCNs) have emerged as highly versatile structural materials that possess exceptional thermomechanical and dynamic properties, all the while retaining their inherent attributes of being lightweight and optically clear. The fabrication of nanocomposites involves the incorporation of carefully calibrated quantities of clay nanofillers into polymer matrixes. Current research expands upon existing coarse-grained (CG) models of nanoclay and poly (methyl methacrylate) (PMMA) and utilize molecular dynamics simulations to methodically explore the thermomechanical characteristics of PCNs. Specifically, the effects of exfoliated and stacked configurations of nanoclays, as well as variations in intermolecular interactions between the nanoclay and polymer constituents were tested. Tensile and shear simulations, as well as interfacial behaviors, are conducted. The intermolecular interaction could have significant influences on Shear Modulus and Young's Modulus, and those influences have their characteristics due to different configurations and different force directions, such as in most cases, exfoliated structures exhibit higher mechanical modulus compared with stacked configurations at varying interaction strengths. Additionally, in the in-plane direction, they demonstrate stronger resistance effects compared with the out-of-plane direction. The interaction between PMMA and nanoclay slows down the global dynamics of PMMA, with a stronger effect observed for higher interaction strength. The impact of nanoclay on the segmental dynamics of PMMA decreases as we move away from the nanoclay layers toward the pure PMMA matrix. These findings provide molecular insights into the arrangement of components in PCNs during deformation and highlight the significance of nanoclay and the interface in determining their mechanical and dynamic properties.Highlights Variation patterns of mechanical modulus with interactions and configurations. The property difference in mechanical modulus due to configurations. Positive correlation between polymer Tg and intermolecular interaction. Global and local confinement effects on molecular stiffness during tension. Dynamical heterogeneity behavior on different interactions and temperatures.