Structure and energetics of biocompatible polymer nanocomposite systems: a molecular dynamics study

Isothermal-isobaric (NPT) molecular dynamics simulations have been performed to investigate the structure, morphology, and energetics of polymer organoclay nanocomposites based on seven nonsteroidal antiinflammatory drugs (NSAIDs), two biocompatible polymers, and hydrotalcite as the clay mineral, both in an anhydrous and in a solvated environment. The results of our theoretical computations show that nanoconfined conformations of smaller NSAIDs are more affected by the presence of water molecules in the clay gallery with respect to their larger counterparts. Moreover, the presence of water in the mineral interlayer space decreases the interaction energy between the NSAID molecules and the clay, and this detrimental effect is further enhanced by the presence of polar moieties onto the NSAIDs. Finally, from the thermodynamics standpoint, the best intercalation results in a solvated environment could be obtained with PVA in the case of less polar drugs, while PHB could be the polymer of choice in the case of highly polar NSAIDs.