Tuning Ether Motifs in Polymers Membranes for Carbon Capture

Polymer membranes suffer from design challenges due to the negative correlation between two principal features of separation performance (permeability and selectivity). In this project, we study the effect of increasing ether oxygen content in the polymer membrane. We investigated five different polymer materials that range in O:C ratio, including polyethylene (PE, O:C=0), polytetramethylene oxide (PTMO, O:C=0.25), polyethylene oxide (PEO, O:C=0.5), poly(1,3-dioxolane) acrylate (PDXLA, O:C=0.67), and polyoxymethylene (POM, O:C=1). Molecular dynamics simulations showed POM has higher CO₂/N₂ and CO₂/O₂ selectivity compared to the commonly used PEO. Additionally, we studied the effect of adding N₂ phobic functional groups to the ends of POM polymer membrane. Adding functional groups to the chain ends of the polymer significantly slows down the gas diffusion thus makes these polymer membranes not optimal candidates for neither CO₂/N₂ nor CO₂/O₂ separation. We have also studied the effect of temperature on the gas diffusion in POM polymer membrane. We have showed that the gas diffusion increases with increasing temperature; however, the diffusion selectivity decreases for both CO₂/N₂ and CO₂/O₂ separation. Our future efforts will focus on studying gas diffusion in polymer mixtures.