Morphological,mechanical and gas-transport characteristics of crosslinked poly(propylene glycol):homopolymers,nanocomposites nd blends

摘要

Linear polyethers possess unusually high CO_2 solubility and,hence,selectivity due to the presence of accessible ether linkages that can interact with the quadrupolar moment of CO_2 molecules.In this work,membranes derived from crosslinked poly(propylene glycol)diacrylate(PPGda)oligomers differing in molecular weight(N),as well as PPGda nanocomposites containing either an organically-modified montmorillonite clay or a methacrylate-terminated fumed silica are investigated and compared with highly CO_2-selective poly(ethylene glycol)diacrylate(PEGda)homopolymer and nanocomposite membranes previously reported.The rheological and permeation properties of PPGda depend sensitively on M,with the elastic modulus decreasing,but CO_2 permeability and CO_2/H_2 selectivity increasing,with increasing M.Incorporation of either nanofiller into PPGda enhances the elastic modulus and reduces the gas permeability in the resultant nanocomposites without strongly affecting CO_2/H_2 selectivity.Blending PPGda and PEGda prior to chemical crosslinking yields binary membranes that exhibit intermediate gas-transport properties accurately described by a linear rule of mixtures.