Molecular Design of Poly(imide–oxadiazole) Membranes for High-Pressure Mixed-Gas Separation

• Published in: Macromolecules Vol. 55; no. 9; pp. 3747 - 3761
• Main Authors: Hayek, Ali, Alsamah, Abdulkarim, Shalabi, Yasser A., Saleem, Qasim, Ben Sultan, Melhan M., Alhajry, Rashed H.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10.05.2022
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.2c00650

The design of new polymeric materials and the search for new classes of polymers for industrial application in membrane-based gas separation have been the focus of several research groups worldwide. Membranes with high productivity and efficiency under harsh operational conditions of pressure and temperature during mixed-gas separation are of great interest. In this paper, we report the preparation of a series of block copolymers of poly­(imide–oxadiazole)­s built from 6FDA, Durene, and four different 1,3,4-oxadiazole-based monomers. The pure- and mixed-gas separation properties of their corresponding membranes were measured. The mixed-gas separation data were collected at a high feed pressure of up to 900 psi. Such mixed-gas separation testing under harsh conditions is required to subject the membranes to environments similar to industrial use. For example, the mixed-gas CO2 permeability of 6FDA-Durene/6FDA-4BAO­(Me) (3:1) was measured at 900 psi to be ∼130 barrer, and the CO2/CH4 selectivity is around ∼24. These results of permeability and selectivity of poly­(imide–oxadiazole) membranes at such high gas feed pressure are considered very attractive and are superior to many glassy polymers reported in the literature and that are industrially observed membranes. This work illustrates well a case scenario of structure–property relationship and demonstrates the exclusivity of mixed-gas testing which could not be predicted from the ideal situation of pure-gas testing. In the near future, the mixed-gas separation properties of thin layer composite and hollow fibers will be evaluated.