Investigation of the gas permeation properties of a polyether sulfone asymmetric membrane via the phase inversion method

Abstract A defect‐free polyether sulfone (PES) asymmetric membrane was prepared by a one‐step phase inversion process and applied gas separation process in this article. The morphology of the PES asymmetric membrane formed via phase inversion that was correlated with the solvent composition, evaporation environment, coagulation bath, and so forth. The results reveal two kinds of coagulation phenomena that lead to different membrane structures and separation results. An instantaneous coagulation PES membrane formed a finger‐like structure within the membrane, and a delayed coagulation PES membrane resulted in a sponge‐like structure membrane. The selectivity of O 2 /N 2 for membrane gas separation indicated that the asymmetric membranes prepared via a one‐step process in this study were defect‐free. Using the phase inversion method to fabricate asymmetric membranes improved the low permeability characteristic of glassy polymers. The maximum permeability of CO 2 for the PES asymmetric membrane in the text can approach 30 Barrer. The results of gas separation for the sponge‐like PES membrane showed that the selectivity of O 2 /N 2 and CO 2 /N 2 was 7.1 and 35.6, respectively. This research showed that a PES asymmetric membrane was fabricated via a one‐step process without further defect repair and was applied effectively for CO 2 membrane gas separation.