Build up 'highway' in membrane via solvothermal annealing for high-efficient CO2 capture

Poly (ethylene oxide) (PEO) membranes are attractive for CO2 capture due to the particular dipolar-quadrupolar interaction between EO units and CO(2 )molecules, which offer high CO2/N-2 selectivity. However, the low CO2 permeability of PEO membranes hampers their practical applications. Herein, a simple solvothermal annealing approach was proposed to enhance the flexibility of PEO chains via 'activating' the disengagement and rearrangement of side chains, which is essential for boosting the gas permeability. The effects of solvothermal annealing temperature, time, and solvent on the CO2/N-2 separation performance were comprehensively investigated. The mechanism for the performance enhancement was proposed: a highway for gas transportation was built up by the released flexible side chains, which were confirmed by the mechanical and Li ion conductivity characterizations. The optimized PEO membrane offers a superior CO2 permeability of 1294 Barrer, a high CO2/N-2 selectivity of 50, and 110-h long-term running stability, being beyond the 2008 Robeson's upper bound line and promoting the practical application of PEO membranes in CO2 capture by reducing the cost.

Automated summary

This study proposes a simple solvothermal annealing approach to enhance the flexibility of PEO membranes and improve their CO2 permeability. The optimized membrane shows high CO2 permeability and selectivity, as well as long-term stability.