(507b) Morphology and Gas Separation Performance of Cnc Incorporated Triblock-Copolymer Nanocomposites Membranes

Energy-efficient gas separations using polymeric membranes are significant interest for separations including natural gas purification and carbon capture. A persistent challenge in this field is the inherent trade-off between permeability and selectivity, restricting overall performance. To address this challenge, incorporating nanoparticles, such as cellulose nanocrystals (CNCs), into polymer membranes has emerged as a promising method to tune the properties of the membranes. In the present work, CNCs were incorporated into several triblock-copolymer Poly (methyl methacrylate)/Poly (n-butyl acrylate)/Poly (methyl methacrylate (PMMA/PBA/PMMA) membranes. Three different variations of PMMA/PBA/PMMA were tested: 33% PMMA content (LA2250), 20% PMMA content (LA2140), and 50% PMMA content (LA4280). Each variation was also tested with 3.3% CNCs loading to assess the impact on gas separation performance. Membranes containing 0% and 3.3% CNCs in each polymer were fabricated via solution casting. Comprehensive thermal, physical and structural characterization was performed, including SAXS, AFM and TGA in order to determine the effects of CNC incorporation on the block copolymer structure. Gas permeation studies were conducted to investigate permeability and solubility for four different gas systems: CO₂, N₂, O₂ and He. Results indicate that gas permeation was reduced across all tested gases for CNC incorporated membranes compared to unloaded membranes while the selectivity remained nearly unchanged. The decrease in permeability was accompanied by an increase in the physical robustness of the membranes upon the incorporation of CNCs. This suggests that the high aspect ratio rod-like CNCs serve a reinforcing role at these low concentrations, leading to decreased chain mobility and therefore decreased permeability. CNCs are highly functionalizable, and ongoing efforts are targeting the effect of varying the particle-polymer interactions in the membranes.