posted on 2023-11-17, 10:03authored byGonçalo
M. C. Silva, Diego A. Pantano, Sophie Loehlé, João A. P. Coutinho
This
work discusses the ability and limitations of the conductor-like
screening model for realistic solvation (COSMO-RS) to predict the
thermodynamic properties of polymer solutions over the entire concentration
range. For that purpose, aqueous mixtures of polyethylene glycol (PEG)
are used as a case study. The activity coefficients of PEG + water
mixtures were calculated as functions of molecular weight and temperature.
The influence of the conformations of the solvated polymer molecules,
the inclusion of a combinatorial term, and the description of the
volume dependence were assessed. Molecular dynamics simulations of
water-solvated polymer molecules were performed to obtain representative
polymer conformers. COSMO-RS is shown to be able to quantitatively
predict the activity coefficients of these systems with the inclusion
of a combinatorial term when the conformational and density dependence
are well described. It is also shown that the scaleup of the polymer
to large molecular weights can be achieved from the sigma profiles
of oligomers with low molecular weight.