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

Abstract

A series of asymmetric membranes based on a trifluoromethylphenylated poly(ether ether ketone) (CF₃-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 (CO₂), oxygen (O₂), and nitrogen by the constant volume method. It was found that the permeabilities of asymmetric membranes were obviously higher than that of CF₃-PEEK dense membrane. The membranes in series 2 showed higher permeability for each gas while the separability for gas pair CO₂/O₂ increased from 3.78 to about 6 comparing with that of the dense membrane.