Humidified Gas Permeation through Modular Polymer Membranes for Enhanced CO2 Separation.

Over the last several decades, polymer-based gas separation membranes have emerged as a competitive, energy-efficient technology for a wide range of applications including carbon capture. The effect of humidity on gas separation membrane performance remains an underexplored topic that can significantly influence separation process efficiency and viability. Despite the many advancements in soft materials for membranes, many promising materials developed in the lab fail to exhibit high selectivities under industrially-relevant conditions, which often involve the detrimental effects of membrane swelling and plasticization resulting from water vapor. In facilitated transport membranes in particular, there is a need to better understand how humidity impacts gas transport mechanisms.

To achieve this, our research involves incorporating functional ligands into PEGDA membranes to tailor the crosslinked polymer functionality and impart high selectivity for carbon capture through facilitated transport. Introducing vapor changes how transport occurs within the membrane due to swelling and plasticization and reactions in the presence of CO₂ and active ligands (amines). Data collection involves the design of a custom temperature-controlled air bath system for humidified permeation measurements with a high-pressure gas feed. Using multicomponent gas and vapor permeation, we are exploring how varying the levels of humidity affects the permeability and selectivity of carbon dioxide for our polymer membranes. As water uptake increases, we expect to see an increase in fractional free volume and an increase in gas permeability due to enhanced segmental mobility. At the same time, we hypothesize that higher CO2 selectivities may result due to the formation of bicarbonate in the membrane.