Asymmetric membranes prepared with trifluoromethylphenylated poly(ether ether ketone) for gas separation

A series of asymmetric membranes based on a trifluoromethylphenylated poly(ether ether ketone) (CF 3 -PEEK) were prepared using a dry–wet phase inversion method. To obtain the asymmetric membranes with defect-free skin, the type and concentration of internal nonsolvent and the evaporation time were carefully investigated. The cross-section of membranes was characterized by scanning electron microscopy. The gas separation performance of asymmetric membranes was tested in terms of gas permeabilities and selectivities for helium, carbon dioxide (CO 2 ), oxygen (O 2 ), and nitrogen by the constant volume method. It was found that the permeabilities of asymmetric membranes were obviously higher than that of CF 3 -PEEK dense membrane. The membranes in series 2 showed higher permeability for each gas while the separability for gas pair CO 2 /O 2 increased from 3.78 to about 6 comparing with that of the dense membrane.