Molecular dynamics simulations of intercalated poly(ε-caprolactone)-montmorillonite clay nanocomposites

The structure and energetics of poly(ε-caprolactone), PCL, chains confined between two platelets of organo-modified montmorillonite clay, are investigated using molecular dynamics techniques. The amount of PCL in the clay gallery has been systematically varied to assess the influence of the interlayer density on the molecular organization. The structural characteristics are examined in terms of interlayer density profiles, radial distribution functions, and dihedral angle distributions. The results show that the interlayer phase organizes into four layers, along with an enhancement of the proportion of extended zigzag chain conformations, with respect to the amorphous polymer bulk. Calculations of the interaction energies between the various subsystems (the PCL chains, the surfactant molecules, and the clay surfaces) clearly show the formation of polar as well as apolar interactions between PCL and the clay surfaces, which can significantly contribute to the polymer intercalation (in addition to the polymer-surfactant interactions).