Highly CO_2-Permeable and -Selective Membranes Derived from Crosslinked Poly(ethylene glycol) and Its Nanocomposites

摘要

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 CO_2-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 CO_2, H_2, N_2, and O_2 have been measured as functions of PEGda molecular weight, nanofiller content and temperature. In all cases, CO_2 displays relatively high permeability, coupled with high CO_2 selectivity, due to the specific interaction between quadrupolar CO_2 and the ether linkages along the PEG backbone, and the accompanying enhancement in CO_2 solubility. Variable-temperature permeation exhibits Arrhenius behavior, and the activation energy for CO_2 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.