Liuyu Wang, Annan Zhou, Jiapei Du
Montmorillonite (MT) has been widely employed as a nanofiller in nacre-inspired polymer-clay nanocomposites (PCN) due to its remarkable thermomechanical properties, wherein interfacial adhesion between MT and polymer matrix is critical to determine PCN’s performance. Herein, the molecular dynamics (MD) method was adopted to evaluate the effects of the cation exchange capacity (CEC) and interlayer cation species of MT on the mechanical properties and interfacial interactions of MT/polyvinyl alcohol (PVA) nanocomposites. The accuracy of MD models were validated against the experimental observations of equilibrium layer spacing and non-equilibrium pull morphologies. Subsequently, validated models were used to investigate the structure, pulling and shear behavior, and stability of interfacial connections of PVA/MT nanocomposites under varying temperatures. The results reveal that higher CEC (130.05 meq/100g) enhances the interfacial PVA density, adhesion strength and temperature resistance (e.g., 36.2% and 213.4% in peak pulling and shear forces relative to 28.68 meq/100 g at 473K). The stable ionic bridges and an extensive hydrogen-bond network are formed at PVA/MT interface, and higher CEC contributes to the stabilization of both bonds. The interface of Ca-MT/PVA shows higher hydrogen bond density and interaction energy than the Na-MT/PVA counterpart, exhibits superior mechanical properties (e.g.,6.5% and 26.9% for pulling and shear force for 130.02 meq/100g at 298K) and thermal stability. This study provides atomistic insights into interfacial mechanisms regulated by MT properties, enabling the design of high-performance clay-based nanocomposites.