Polymer-MOF Network Enabling Ultrathin Coating for Post-Combustion Carbon Capture

Permeance-selectivity trade-off and high temperature resilience are key challenges in development of membranes for post-combustion carbon capture. While mixed matrix membranes (MMMs) consisting of polymers and metal-organic frameworks (MOFs) offer the potential to address the challenges, they are limited by the low loading of MOFs in the thin film layer. Herein, we propose an inverse synthesis strategy to form polymer-MOF networks by copolymerizing monomers with functionalized UiO-66 nanoparticles. This process yields a finely dispersed, easily processable solution, enabling defect-free, thin polymer-MOF coatings with up to 40 wt % MOF loading within the polyethylene oxide-based polymers on polyacrylonitrile supports. The membrane with 40 wt % MOF demonstrated a 212 % increment in CO₂ permeance at 25 °C and maintained a selectivity of 20 at 60 °C, which is attributed to the stable diffusivity selectivity of MOFs at high temperature. Furthermore, the membrane was evaluated with mixed gas and 83 % relative humidity (RH) at 60 °C, achieving a CO₂ permeance up to 2793 GPU and a CO₂/N₂ selectivity of 21.6. This work offers insights into the design of practical mixed matrix membranes, which not only paves the way towards energy efficient carbon capture from flue gas, but also provides more possibilities for other applications.