Interfacially initiated polymerization of epoxides: A thin-film synthesis platform for XLPEO gas separation membranes.

Crosslinked poly (ethylene oxide) (XLPEO) membranes are leading candidates for membrane post-combustion carbon capture, because of their high CO 2 /N 2 selectivity and CO 2 permeability. However, their crosslinked nature makes it difficult to process them into thin films through conventional coating techniques. In this study, interfacially initiated chain growth polymerization of epoxides is used to circumvent the XLPEO processing challenge whilst allowing in-situ crosslinking. The interfacial design strategy yields intrinsically crosslinked, epoxide-based PEO (eXLPEO) thin-film composite gas separation (GS) membranes consisting fully of CO 2 -philic ether bonds. An eXLPEO selective layer made from poly (ethylene glycol) diglycidyl ether was successfully deposited on a PAN support and, after introduction of densification steps and a PDMS sealing, gas selective membranes were obtained. Synthesis-structure-performance analysis revealed that multiple reaction condition combinations result in highly selective membranes with a tunable chemical structure. The best performing membranes showed CO 2 /N 2 separation factors of 58 at 35 °C, with a stable operation at pressures from 2 to 10 bar, and retaining a separation factor of 30 at 65 °C. However, all membranes had a low CO 2 permeance (<10 GPU), probably due to pore impregnation of the support layer. This work demonstrates for the first time the viability of interfacial polymerization for the synthesis of thin film eXLPEO GS membranes. [Display omitted] • Epoxide chemistry is a novel platform for thin-film composite (TFC) gas separation membrane synthesis. • Crosslinked poly (ethylene oxide) TFC were synthesized using epoxide interfacial polymerization. • The chemical structure of epoxide-TFC is controlled by the monomer/initatior ratio. • Membranes show high CO 2 /N 2 selectivity, even at elevated temperatures. • The hydrophilicity of the monomers caused pore impregnation. [ABSTRACT FROM AUTHOR]