Enhancing Cross-Linked PEO Membrane Properties By a Highly-Efficient Post-Treatment Strategy

Herein, we first report an extremely versatile strategy to significantly improve gas transport properties of PEO-containing cross-linked membranes based on their specific swelling properties. Low-molecular-weight poly (ethylene glycol) (PEG) was deliberately incorporated into synthesized swellable pure PEO cross-linked membrane via immersing PEO membrane into PEG-water solution and membranes with various PEG loadings are obtained. The imbedded PEG molecules can be located between polymer chains to improve chain mobility and increase chain distance, resulting in the increase of fractional free volume (FFV), which is in favor of gas diffusion. On the other hand, the increment of CO₂-philic building units resulting from the imbedded PEG molecules leads to higher CO₂ solubility. Finally, the simple treated membranes exhibit significant increments in both CO₂ permeability (up to 762%) and CO₂/H₂ selectivity (up to 86%). The separation performance was correlated nicely with the microstructure of the membranes. This study may provide useful insights about the formation and mass transport behaviour of highly-efficient polymeric membrane applicable to clean energy purification and CO₂ capture, and possibly bridge the material-induced technology gap between academia and industry. Most importantly, our discovered strategy has great potential for treating composite membranes and regenerating “aged” membranes to realize clean energy purification and CO₂ capture by membrane technology.