Solution‐processable cross‐linked poly(ethylene oxide) ultrathin composite membranes via ultraviolet polymerization for CO 2 capture

Abstract Cross‐linked poly(ethylene oxide) (PEO) synthesized via free radical polymerization is one of the most promising polymer membrane materials for CO 2 capture. However, it remains a major challenge to obtain soluble cross‐linked PEO polymers via facile and controllable methods, so as to fabricate solution‐coated ultrathin composite membranes with high CO 2 permeance. To address this issue, we proposed an intermittent ultraviolet (UV) irradiation strategy that enables precise control over the free radical polymerization process of PEO monomers and improves polymerization uniformity. Consequently, we successfully synthesized a soluble PEO polymer sufficiently cross‐linked and fabricated it into an ultrathin (~45 nm), defect‐free selective layer via simple solution coating methods. The optimized membrane achieves an ultrahigh CO 2 permeance of 3074 gas permeation units (GPU), along with a desirable CO 2 /N 2 selectivity of 38.3, outperforming current cutting‐edge membrane materials. More importantly, this membrane exhibits good scalability and operational stability, offering great promise for continuous large‐scale fabrication and practical carbon capture applications.