Design of ultrathin cross-linked poly(ethylene oxide) selective layer for high-performance CO₂ capture

Cross-linked poly(ethylene oxide) (PEO) is a highly promising membrane material for CO₂ capture, as it allows fast and selective CO₂ transport. However, the facile fabrication of an ultrathin cross-linked PEO selective layer for thin-film composite (TFC) membrane to achieve high CO₂ separation performance remains challenging. To address this issue, we reported the design of a soluble high-permeability cross-linked PEO polymer and the fabrication of it into an ultrathin CO₂-selective layer through a simple coating technique. The as-synthesized cross-linked PEO polymer contains abundant poly(dimethylsiloxane) (PDMS) segments, leading to highly improved free volume and affinity towards CO₂, which result in high CO₂ diffusivity, solubility, and consequently high CO₂ permeability (528 Barrer). TFC membranes with an ultrathin selective layer (∼128 nm) were successfully fabricated using the PEO polymer, leading to superior CO₂ capture performance (CO₂ permeance = 2650 GPU, CO₂/N₂ = 20) for CO₂/N₂ mixture separation in a long-term stability test, exceeding the target performance for carbon capture. Given their high separation performance, excellent stability, and scalable fabrication route, our PEO-based membranes hold great promise for post-combustion CO₂ capture.