Nanocellulose-Incorporated Composite Membranes of PEO-Based Rubbery Polymers for Carbon Dioxide Capture

To achieve sustainable and energy-efficient CO₂ capture processes, it is imperative to develop membranes that possess both high CO₂ permeability and selectivity. One promising approach involves integrating high-aspect-ratio nanoscale fillers into polymer matrices. The high-aspect-ratio fillers increase surface area and improve interactions between polymer chains and gas molecules passing through the membrane. This study focuses on the integration of cellulose nanocrystals (CNCs) with an impressive aspect ratio of around 12 into rubbery polymers containing polyethylene oxide (PEO), namely PEBAX MH 1657 (poly[ether-block-amide] [PEBA]) and polyurethane (PU), to fabricate mixed-matrix membranes (MMMs). By exploiting the interfacial interactions between the polymer matrix and CNC nanofillers, combined with the surface functionalities of CNC nanofillers, the rapid and selective CO₂ transport is facilitated, even at low filler concentrations. This unique feature enables the development of thin-film composites (TFCs) with a selective layer around 1 μm. Notably, even at a filling ratio as low as 1 weight percent, the resulting membranes exhibit remarkable CO₂ permeability (>90 Barrer) and CO₂/N₂ selectivity (>70). These findings highlight the potential of integrating CNCs into rubbery polymers as a promising strategy for the design and fabrication of highly efficient CO₂ capture membranes.