Thermodynamic properties of poly(vinyl alcohol) with different tacticities estimated from molecular dynamics simulation

We used molecular dynamics simulation together with the OPLS-AA force field along with a high temperature equilibration protocol proposed by Belmares et al. to calculate selected thermodynamic properties of poly(vinyl alcohol) (PVA) with different tacticities. The results showed that the OPLS-AA force field was able to reproduce specific volumes, thermal expansion coefficients, glass transition temperatures and solubility parameters of the PVAs over a wide range of temperatures (200-550 K). PVA with different tacticities in the amorphous phase showed different solubility parameters but possessed similar specific volumes, thermal expansion coefficients and glass transition temperatures. For heat capacities, 300% overestimations were obtained. Such overestimations were reduced significantly to about 30% by applying the quantum correction method of Berens et al. We have also applied the newly developed two-phase thermodynamic (2 PT) approach in an attempt to further improve the results but failed.