Molecular dynamics simulations of polyvinyl butyral solvation in methylal solvent in comparison with water, methanol, and ethanol solvents

Methylal has attracted attention as a promising organic solvent for polymers and thus is widely applied in industrial fields, but its solubility is not yet fully understood at the atomic scale. In this work, we report a classical molecular dynamics study of the solvation of polyvinyl butyral (PVB) in methylal solvent, comparing it with other conventional solvents, such as water, methanol, and ethanol. From the analysis of gyration radius, our results demonstrate that PVB20 adopts a folding and unfolding conformation in methylal and other solvents, respectively. We reveal through the analysis of the radial distribution function and structural factor that the strength of intermolecular interaction between the PVB and the solvent increases as the molecular size of the solvent molecule decreases, thereby showing the lowest intermolecular interaction in methylal, and moreover, hydrogen bonding between the solvent molecules is absent in methylal, which is in contrast to water, methanol, and ethanol solvents. Our calculations of solvation free energy and mixing energy confirm that methylal has superior solubility for the PVB polymer to other solvents, highlighting the significance of methylal in dissolving polymer.