Fig. 7: SEM images and gas separation performance of Matrimid-Cyclen-5% TFC membrane.

a Cross section and b surface SEM images of the Matrimid-Cyclen TFC membrane with different thickness. c Gas separation performances of the Matrimid-Cyclen TFC membrane with different average thicknesses. d Comparison of He/CH4 separation performance of Matrimid-Cyclen TFC membranes with available literature data.