A theoretical study of structure–solubility correlations of carbon dioxide in polymers containing ether and carbonyl groups

Abstract

This work involves a theoretical study to investigate the effects of the structure on CO₂ sorption in polymers, where poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), poly(vinyl acetate) (PVAc), poly(ethylene carbonate) (PEC) and poly(propylene carbonate) (PPC) were examined. In the theoretical approach, the multi-site semiflexible chain model and the renormalized technique of electrostatic potentials were incorporated into the polymer reference interaction site model (PRISM). To test the theory, molecular dynamic simulations were performed using the TraPPE-UA force field. The theoretically calculated reduced X-ray scattering intensities and intermolecular correlation functions of these five polymers are found to be in qualitative agreement with the corresponding molecular simulation data. The theory was then employed to investigate the distribution functions between CO₂ and different sites of the polymers with consideration of the Lennard-Jones, potential of mean force, and columbic contributions. Based on the detailed structure characteristics of CO₂ in contact with different groups, the CO₂ coordination molecular numbers were obtained and their sorption intensities analyzed. Finally, the sorption isotherms of CO₂ in these five polymers were calculated. The results for PEO, PPO and PVAc are close to the available experimental curves, and the trend of CO₂ solubility is PPC > PEC > PVAc ∼ PPO > PEO.