Molecular dynamics simulations to investigate polymer–polymer and polymer–metal oxide interactions

Abstract

Polymer–polymer interactions in majority of engineering polymers are difficult to measure experimentally, since many polymers are usually insoluble in solvents, have high glass transition temperatures, and are sometimes poorly characterized. Therefore, applying molecular modeling strategies would be helpful in such situations in order to provide useful information, which would be difficult to obtain by other means. Poly(methyl methacrylate), PMMA, is a widely used engineering polymer that exists in a glassy state at room temperature. Therefore, we have selected PMMA to perform the molecular dynamics simulations to investigate its interfacial interaction with many other important polymers such as PAN, PC, PEO, PES, PMS, PU, PVAc, PVDF, PVME and PVP. Small molecular fragments of repeating units of these polymers were chosen for interaction studies, whose polymers and/or their blends with PMMA are used in many engineering applications. The COMPASS force field methodology was used in the present study for oligomers containing up to 10-mers for simulations to compute solubility parameters that are closely agreeable with the experimental data. Molecular dynamics (MD) simulations have also been performed to explore the adsorption behavior of MMA with several metal oxides (Al₂O₃, Fe₂O₃, SiO₂ and TiO₂), since such studies are important in developing polymer composites. Interfacial interactions between MMA and metal oxides have been calculated using the vibrational absorptions in order to identify the functional groups that might interact quite favorably with the PMMA.