Preparation and gas separation properties of partially pyrolyzed membranes (PPMs) derived from copolyimides containing polyethylene oxide side chains

► Partially pyrolyzed membranes (PPMs) were prepared from copolyimides with side PEO. ► PEO side chains were removed at 385 °C to prepare the corresponding PPMs. ► The copolyimide framework of PPMs was maintained after the pyrolysis. ► Gas permeability of PPMs increased compared to the corresponding precursors. ► Pyrolysis of the PEO groups increased the free volume element size and concentration.