Polymeric Amine-Based Facilitated Transport Membranes for Post-Combustion Carbon Dioxide Capture

Facilitated transport membranes make use of the reversible reaction of target gases with carrier molecules within the membrane to enhance the permeability and selectivity relative to non-interacting gases. Polyvinylamine (PVAm) is one of the most commonly examined polymers for CO₂ capture facilitated transport membranes due to its high density of amine groups and good film forming properties. This poster will present our recent research on PVAm membranes. PVAm is typically prepared by partial hydrolysis of poly(N-vinylformamide) (PNVF), yielding products that are a random copolymer of vinylamine and vinylformamide repeat units. We are examining the effect of degree of hydrolysis to PVAm on the membrane permeability and physical properties. For example, a membrane with 45 mol% vinylamine units had a CO₂ permeability of 160 barrer and CO₂/N₂ selectivity of 74 at 25 °C under 95% relative humidity. A free-standing 35-micron film of the dry polymer had a tensile strength of 54 ±13 MPa, tensile modulus of 7.7 ±1.4 GPa, and failure strain of 1.9 ±0.5%. The presence of atmospheric moisture has a significant effect on the physical properties of PVAm films, and we observed an 11 °C decrease in glass transition temperature (T_g) for the PVAm films for each 10% increase in ambient relative humidity, as measured by the loss modulus peak in dynamic mechanical analysis (DMA) with a relative humidity accessory.