Highly CO₂‐Permeable and ‐Selective Membranes Derived from Crosslinked Poly(ethylene glycol) and Its Nanocomposites

Abstract Crosslinked poly(ethylene glycol diacrylate) (PEGda) oligomers differing in molecular weight, and their nanocomposites prepared with up to 10 wt.‐% methacrylate‐functionalized fumed silica (FS) or an organically‐modified nanoclay, have been examined as amorphous CO₂‐selective membranes. These novel materials have been characterized by dynamic rheology before and after crosslinking to ascertain the effect of incorporated FS on mechanical properties. The permeabilities of CO₂, H₂, N₂, and O₂ have been measured as functions of PEGda molecular weight, nanofiller content and temperature. In all cases, CO₂ displays relatively high permeability, coupled with high CO₂ selectivity, due to the specific interaction between quadrupolar CO₂ and the ether linkages along the PEG backbone, and the accompanying enhancement in CO₂ solubility. Variable‐temperature permeation exhibits Arrhenius behavior, and the activation energy for CO₂ permeation is found to be i) markedly lower than that of any of the other gases examined, and ii) independent of both PEGda molecular weight and nanofiller content.