Molecular Dynamics Study of Ternary Montmorillonite-MT2EtOH-Polyamide-6 Nanocomposite: Structural, Dynamical, and Mechanical Properties of the Interfacial Region

In this work, we studied the structural, dynamical, and mechanical properties of the interfacial region I of a ternary montmorillonite-MT2EtOH-polyamide-6 nanocomposite using molecular dynamics modeling. Through analysis of structural parameters, including the density, bond orientation, and vector to the second-neighbor orientation, we demonstrated that, in this nanocomposite, the polymer has a laminate structure and estimated the Young modulus of its different regions. The region closest to the clay surface was the hardest with an elastic modulus of more than twice that of the pure polyamide; the other regions did not exhibit as high an elastic modulus. Closest to the clay surface, the polymer chains were aligned in the direction parallel to the platelet, which appears to explain the hardening of this region. In addition, the atomic mobility was shown to differ significantly for atoms located in the interfacial space and far away from filler particles. Therefore, we can conclude that atoms near the interface are strongly constrained, whereas those far from the interface exhibit the same mobility as that of the pure polymer. All of these analyses enabled us to estimate the thickness of the interfacial region, which did not exceed 15 angstrom.