Metal-Coordinated, Dual-Crosslinked PIM Polymer Membranes for Upgraded CO₂ Separation: Aging and Plasticization...

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Polymers of intrinsic microporosity (PIMs) face limitations in CO2 separation, including moderate selectivity and instability.
• Existing PIM-1 membranes show potential but require enhancements for practical industrial use.

Purpose of the Study:

• To improve the CO2 separation performance of PIM-1 by incorporating metal ions.
• To investigate the effect of dual crosslinking on polymer structure and gas transport properties.
• To develop stable and high-performance membranes for mixed gas separation.

Main Methods:

• Incorporation of metal ions into uniformly hydrolyzed PIM-1 (cPIM) via ionic and coordination bonding.
• Dual crosslinking using metal ions with carboxylic acid (─COOH) and amide (─CONH2) groups.
• Fabrication and testing of metal-coordinated membranes for CO2/N2 and CO2/CH4 separation.

Main Results:

• Optimized zinc-coordinated membranes achieved CO2 permeability of ~2,500 Barrer with CO2/N2 selectivity of 27.1 and CO2/CH4 selectivity of 23.
• Performance surpassed pristine cPIM and the 2008 Robeson upper-bound limits.
• Membranes demonstrated long-term stability (20 days) and anti-plasticization up to 20 bar.

Conclusions:

• Dual crosslinking with metal ions effectively restructures PIM-1, enhancing CO2 separation capabilities.
• The modified membranes offer superior permeability, selectivity, and stability for industrial gas separations.
• These membranes show significant promise for practical mixed gas separation applications.