Equation of state of PEG/PEO in good solvent. Comparison between a one-parameter EOS and experiments

- The theoretical EOS gives a reasonable estimation for polymer concentration.
- Results from this study have implications for probing macromolecular interactions when applying the osmotic stress method.
- The primitive model and the cell mode can be used to accurately determine osmotic pressures of silica dispersions.

We investigate, through osmotic pressure measurements, the validity of the single-parameter equation of state (EOS) for solutions of polyethylene glycols in water, by Cohen et al.1,2 We show that it is physically meaningful and that a reasonable good correspondence between the osmotic pressures for PEG35 in large range of concentrations is obtained. We also take the chain length dependence into account in our analysis, as suggested by Cohen et al. By recalculating the experimental pressures in the paper by Jönsson et al.3 applying the new calibration curve, which is based on the experimental results obtained in this study and the EOS obtained by Cohen et al., there is almost a perfect correspondence between the simulations and the experiments. These results have implications for correctly probing macromolecular interactions in wide range of systems when applying the osmotic stress method.