High-Performance Self-Cross-Linked PGP–POEM Comb Copolymer Membranes for CO₂ Capture

Abstract

We report a high performance CO 2 capture membrane based on the copolymerization and self-cross-linking of poly(glycidyl methacrylate- g -poly(propylene glycol))- co -poly(oxyethylene methacrylate) (PGP–POEM) comb copolymer. The epoxide–amine reaction is responsible for the self-cross-linking reaction, which takes place under mild conditions without any additional cross-linkers or catalysts. The effects of self-cross-linking on the membrane properties are investigated by comparing the copolymers with those containing a low PPG grafting density ( l -PGP–POEM). Furthermore, the gas separation performance of the membranes is systematically investigated as a function of POEM content in the comb copolymer. Both the permeance and selectivity of the PGP–POEM membranes are enhanced simultaneously with increase in the POEM content up to 51.2 wt % (PGP–POEM13), at which the best performance was achieved among the membranes. The high performance results from the reduced diffusion of N 2 due to the self-cross-linked structure as well as the increased CO 2 solubility due to the high content of ether oxygen groups in the comb copolymer. By optimizing the membrane thickness, the performance is further improved up to a CO 2 permeance of 500 GPU (1 GPU = 10 –6 cm 3 (STP)/(s cm 2 cmHg)) and CO 2 /N 2 selectivity of 22.4, which is close to the commercialization target area of CO 2 capture membranes. This work suggests a simple and economical cross-linking method to fabricate the membranes with excellent gas separation performance.