Atomistic simulations of isotactic and atactic poly(methyl methacrylate) melts: exploring the backbone conformational space

Molecular dynamics simulations were performed separately on an isotactic poly(methyl methacrylate) (PMMA) melt and on an atactic PMMA melt. These simulations allow for a detailed atomistic exploration of the conformational space about the polymers' backbone at a temperature above the glass transition for both polymers, which is experimentally difficult to accomplish. In agreement with previous experimental and theoretical studies, we found the trans-trans backbone conformation to be the most energetically stable, followed by the trans-gauche conformations. Unique in this study is the ability to attribute how the underlying meso and racemic diad pairs contribute to the overall backbone population. Additional simulations were performed on methyl methacrylate, the compound that forms PMMA through radical reactions. These latter simulations help to validate our recently created force field for use in condensed-phase simulations.