Atomistic simulation of CO2 solubility in poly(ethylene oxide) oligomers

We have performed atomistic molecular dynamics simulations coupled with thermodynamic integration to obtain the excess chemical potential and pressure-composition phase diagrams for CO₂ in poly(ethylene oxide) oligomers. Poly(ethylene oxide) dimethyl ether, CH₃O(CH₂CH₂O)_nCH₃ (PEO for short) is a widely applied physical solvent that forms the major organic constituent of a class of novel nanoparticle-based absorbents. Good predictions were obtained for pressure–composition–density relations for CO₂ + PEO oligomers (2 ≤ n ≤ 12), using the Potoff force field for PEO J. Chem. Phys. 136, 044514 (2012)] together with the TraPPE model for CO₂ AIChE J. 47, 1676 (2001)]. Water effects on Henry’s constant of CO₂ in PEO have also been investigated. Addition of modest amounts of water in PEO produces a relatively small increase in Henry’s constant. Dependence of the calculated Henry’s constant on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length.