Abstract
In recent years, inverse gas chromatography (IGC) and molecular dynamics simulation methods have been used to characterize the solubility parameters and surface parameters of polymers, which can provide quantitative reference for the further study of the surface and interface compatibility of polymer components in the future. In this paper, the solubility parameters and surface parameters of two kinds of common alcoholysis, PVA88 and PVA99, are studied by using the IGC method. The accuracy of the solubility parameters obtained by the IGC experiment is verified by molecular dynamics simulation. On the basis of this, the influence of repeated units of polyvinyl alcohol (PVA) on solubility parameters is studied, so as to determine the appropriate chain length of the PVA for simulation verification calculation. The results show that the solubility parameters are not much different when the PVA chain length is 30 and above; the numerical trends of the solubility parameters of PVA88 and PVA99 at room temperature are the same as the results of molecular dynamics simulation; the dispersive surface energy and the specific surface energy are scattered with the temperature distribution and have a small dependence on temperature. On the whole, the surface energy of PVA99 with a higher alcoholysis degree is higher than that of PVA88 with a lower alcoholysis degree. The surface specific adsorption free energy () indicates that both PVA88 and PVA99 are amphoteric meta-acid materials, and the acidity of PVA99 is stronger.
Highlights
Polyvinyl alcohol (PVA) is a kind of environmental friendly water-soluble polymer material [1] with good film-forming property, excellent performance, non-toxicity, and degradability [2,3,4]
100 ps, relax the structure, and release the tension of the system to achieve the equilibrium of geometric conformation; 400 ps was balanced under the NPT ensemble, and 100ps was run through NVT, and the trajectory file was analyzed to calculate the solubility parameters of two alcoholysis degrees at 298.15 K. (The force field selection for all molecular dynamics simulation processes: COMPASSII Version 1.2, temperature control method: nose, pressure control method: Andersen, step length 1fs, accuracy: 0.001 kcal/mol, cutoff distance: 12.5 A.)
The solubility parameters of polyvinyl alcohol (PVA) with different alcoholysis degrees calculated by the two methods are significantly similar; comparing the data measured by the inverse gas chromatography (IGC) method and the PVA molecular dynamics method can prove the reliability of the IGC method, and it can prove that the PVA molecular dynamics method can be used to calculate and verify the experimental results
Summary
Polyvinyl alcohol (PVA) is a kind of environmental friendly water-soluble polymer material [1] with good film-forming property, excellent performance, non-toxicity, and degradability [2,3,4]. This paper provides a quantitative reference for future research on the relationship between the surface characteristics and structure of PVA composites by using the IGC method and computer simulation to calculate the relevant parameters of PVA with different alcoholysis degrees. It can help other researchers choose the appropriate type of PVA when studying the PVA composites
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