Control of Microporous Structure in Conjugated Microporous Polymer Membranes for Post-Combustion Carbon Capture

Membranes offer a potentially energy-efficient and space-saving solution to reduce CO2 emissions and combat global warming. However, engineering membranes with advanced materials for high permeance and reasonable selectivity is a pressing need. In this context, a series of carbazole-based conjugated microporous polymer (CMP) membranes are fabricated with thicknesses of a few hundred nanometers through in situ electropolymerization for post-combustion carbon capture. The findings reveal that various experimental conditions, including the monomer concentration, electric potential, and cyclic voltammetry (CV) cycling number, largely impact the polymerization degree of the carbazole-based CMP, thus influencing the mode of polymer chain packing. An optimal polymerization degree leads to a larger micropore size and a higher fractional free volume (FFV), thus allowing fast CO2 transport. The study first demonstrates the feasibility of using CMPs to fabricate thin film composite (TFC) membranes for post-combustion carbon capture and confirms the high controllability of their micropores. These insights provide instructive guidance for the future advancement of CMP applications in membrane fabrication for gas separation and other fields that require precise micropore generation and design.