Understanding the effect of functionalization in CNT-epoxy nanocomposite from molecular level

The excellent physical, mechanical, thermal and electrical properties of carbon nanotubes (CNTs) make them the promising reinforcements for polymer materials. The resulting nanocomposites have been applied in various applications, including but not limited to aerospace components and nanoelectronics. The mechanical performance of CNT reinforced nanocomposites is significantly affected by the interfacial interactions between CNT and polymer matrices. Enhancing the CNT-polymer interface from molecular level, such as chemical functionalization on CNTs, opens new perspectives for improving the mechanical properties of nanocomposites. Although there is a risk that functionalization may destroy the perfect surface of CNTs during fabrication, such chemical treatment can provide desired CNT dispersion state and orientation, resulting in significant improvement in mechanical properties of polymer nanocomposites. In this work, epoxy nanocomposite systems with pristine and functionalized CNTs are modeled respectively. Molecular dynamics simulations are applied to investigate the interfacial characteristics and the mechanical responses of these CNT-polymer nanocomposites. The results reveal that the functionalization can enhance the interfacial shear stress and the Young's modulus of CNT-epoxy nanocomposites. The functional groups not only provide stronger interfacial adhesion with the epoxy matrix, but also act as the sites of mechanical interlocking during deformation. The understanding of the reinforcing mechanism from atomistic level provide physical new insights to material design for advanced nanocomposites.