Synthesis and Gas Transport Properties of Poly(2,6-dimethyl-1,4-phenylene oxide)-Silica Nanocomposite Membranes

The emulsion polymerized mixed matrix (EPMM) method is a new approach to prepare nanocomposite membranes, in which inorganic nanoparticles are synthesized in situ at the interface of a dispersed aqueous phase in a continuous phase of polymer solution. In this paper, we report the synthesis and characterization of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based EPMM membranes, in which silica nanoparticles are synthesized by the polymerization of tetraethylorthosilicate (TEOS) in the presence of two different co-solvents, ethanol and acetone, which are soluble in both the aqueous phase and the polymer solution. The EPPM membranes prepared in the presence of acetone show greater conversions of TEOS and a different structure of the synthesized silica nanoparticles compared to the EPMM membranes prepared in the presence of ethanol. The former membranes are both more permeable and more selective for O-2/N-2 and CO2/CH4. Both types of EPMM membranes are more permeable than the reference PPO membranes. However, while their O-2/N-2 selectivity is practically unchanged, their CO2/CH4 selectivity is decreased compared to the reference PPO membranes.