Molecular mechanics studies of specific interactions in organomodified clay nanocomposite

Molecular mechanics calculations were performed to characterize organomodified clay. Supercells containing montmorillonite with a cation exchange capacity of 70 and 140 meq/100 g organomodified with three mono-tailed and one di-tailed surfactants were constructed. The dependency of the total energy with respect to the basal spacing was calculated and used to gain insight into the equilibrium distance and the nature of the interactions. Equilibrium distances obtained for mono-tailed surfactants are in agreement with experimental results. The total energy versus distance curves are fitted to a Morse function allowing the analysis of the local behaviour at equilibrium. This procedure allows describing the ability of Ditallow surfactant to facilitate the intercalation of organic molecules.