Chemical Modification of Polymer-Based Membranes for Carbon Capture

The threat of climate change is strengthening as a result of the continued release of greenhouse gases into the atmosphere. Our group is cultivating polymer-based membrane technology for gas separation which aims to reduce carbon dioxide levels in the atmosphere when applied to industrial gas byproducts or direct air capture. Gas separation by distillation is widely used in industrial systems but it is energy intensive and costly. Polymer membranes are relatively cheap and have the potential to reduce energy usage of separations.

Our group is exploring how altering the chemical structure of polymer membranes affects permeability and selectivity of carbon dioxide by functionalizing a PEG based membrane with an active ester side chain using “click chemistry.” Click chemistry allows various amine groups to be easily added to the base membrane. Our hypothesis is that the addition of amine ligands to the polymer’s crosslinked scaffolding would create favorable interactions with carbon dioxide, thus increasing selectivity. Gas permeabilities and solubilities will be tested on samples substituted with amine ligands with different pKa values such as pyridine, imidazole, and piperidine. Gas diffusion coefficients will then be determined using the solution diffusion model. We hypothesize that amines with lower pKa values may have weaker interactions with CO₂ that could facilitate faster diffusion jumps and lead to higher permeability.