Improving transport properties in polyetherimide asymmetrical membranes by polydopamine surface modification

Abstract Gas separation processes are often used on both laboratory and industrial scale. Asymmetric polymeric membranes are the main material used for these processes. The performance of membranes used in this process is mainly evaluated based on their transport properties: permeation and selectivity. Polyetherimide asymmetric membranes surface was directly modified by polydopamine coating, to evaluate the gas and water vapour permeation performance improvement. Measurements of interaction and surface energies of the modified membranes showed attenuation of the hydrophobic polyetherimide characteristic (from 78° to 55° water contact angle). The results of the gas permeation and water vapour transport measurements pointed to an increase in the permeability of the modified membranes, ranging from 2.19–4.86 GPU for pristine membranes to 21.07–28.3 GPU. However, gas selectivity did not show significant improvement, except for CO 2 /O 2 . It was possible to conclude, through this study, that the bioinspired surface modification with polydopamine coating, in addition to being a simple procedure, was efficient in terms of modifying the physical and chemical properties of the membranes to improve the hydrophilicity and gas and vapour permeability.