Engineering CO₂-Ultraselective Membranes: Molecularly Tailored Low-Crystallinity Polyvinylamine-PEGDGE Networks

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Facilitated transport membranes (FTMs) are crucial for efficient CO2 separations.
• Existing FTMs face challenges in balancing selectivity and permeability.
• Developing membranes that surpass current performance benchmarks is essential for carbon capture technologies.

Purpose of the Study:

• To design and develop novel FTMs with enhanced CO2/N2 selectivity and permeance.
• To investigate the synergistic effects within the membrane structure that facilitate CO2 transport.
• To explore the potential of these membranes for scalable carbon capture applications.

Main Methods:

• Fabrication of composite membranes using polyvinylamine (PVAm) and a cross-linked network of PVAm-functionalized poly(ethylene glycol)diglycidyl ether (PEGDGE).
• Characterization of membrane performance for CO2/N2 separation, including selectivity and permeance measurements.
• Molecular dynamics (MD) simulations to analyze the membrane's free volume and transport mechanisms.

Main Results:

• The best composite membranes (PM/PP-10)/polysulfone (PSf) achieved a CO2/N2 selectivity of 230 and a CO2 permeance of 100 GPU.
• Performance significantly surpassed pristine PVAm/PSf membranes and exceeded the 2019 Robeson upper bound.
• MD simulations indicated increased fractional free volume (FFV) in the PVAm matrix due to the PP-10 network, enhancing CO2 diffusion.

Conclusions:

• The developed FTMs demonstrate a facile and scalable approach for CO2-ultraselective membrane development.
• Synergistic effects from CO2-philic groups and hydrophilic networks enhance CO2 transport and stabilize carriers.
• These findings offer a promising pathway for advancing carbon capture technologies from flue gases.