Multifunctional Amine-Containing PVA-g-POEM Graft Copolymer Membranes for CO2 Capture

CO2 separation technology using polymeric membranes has emerged as a viable solution to mitigate the rapidly increasing anthropogenic CO2 emissions, which are directly linked to global warming and climate anomalies. However, in order to improve the gas separation performance, an intrinsic problem of polymeric membranes, i.e., a trade-off relationship between permeability and selectivity, needs to be addressed. In this study, a solid-state facilitated transport membrane is prepared by blending CO2-philic, amine compatible poly(vinyl alcohol)-g-poly(oxyethylene methacrylate) (PVA-g-POEM) graft copolymer and diethylenetriamine (DETA) carriers. The graft copolymer consisting of PVA main chains and POEM side chains is synthesized via one-pot free radical polymerization and used as a polymer matrix. With the incorporation of 10 wt % of DETA into the polymer, the membrane exhibits a high CO2 permeance of 402.5 GPU (1 GPU = 10(-6) cm(3)(STP)/(s-cm(2).cmHg)) and CO2/N-2 selectivity of 52.1. The enhanced performance of the membrane results from multifunctional amine carriers in the graft copolymer owing to facilitated transport of CO2 and an increase in the crystallinity of the polymer. DETA acts as a seed for crystallization of PVA chains at a low loading, which leads to a reduced N-2 permeance. The membrane exhibits good stability without any performance degradation over 2 weeks in the solid state. The superior separation property of the PVA-g-POEM membrane containing DETA distinguishes this facilitated transport membrane from other similar membranes and commercial membranes.