Ionic Cross-Linked MOF-Polymer Mixed-Matrix Membranes for Suppressing Interfacial Defects and Plasticization Behavior

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Science

Background:

• Plasticization and interfacial defects hinder the performance of mixed matrix membranes (MMMs).
• Metal-organic frameworks (MOFs) and polymers are key components in advanced membrane technology.
• Addressing these limitations is crucial for developing high-performance separation membranes.

Purpose of the Study:

• To synthesize ionic cross-linked MOF MMMs using a dual brominated polymer and MOF components.
• To investigate the impact of MOF loading and ionic cross-linking on gas permeation properties.
• To evaluate the resistance to plasticization in the developed MMMs.

Main Methods:

• Synthesis of brominated MIL-101(Cr) nanoparticles and brominated polyimide (6FDA-DAM-Br).
• Formation of ionic cross-linked MMMs using N,N'-dimethylpiperazine as a cross-linker.
• Systematic investigation of gas permeation (H2, CO2, CH4, N2) and plasticization resistance.

Main Results:

• Ionic cross-linked 40 wt% MOF-polymer MMMs showed significantly enhanced H2 (1640 Barrer) and CO2 (1981 Barrer) permeability.
• Selectivities for H2/CH4, H2/N2, CO2/CH4, and CO2/N2 were slightly decreased but remained high (16.9-20.5).
• Permeabilities were 2-3 times higher than pure polyimide membranes, with substantially improved resistance to plasticization.

Conclusions:

• Ionic cross-linking effectively mitigates plasticization and interfacial defects in MOF MMMs.
• The developed MMMs demonstrate superior gas transport properties and enhanced stability.
• This strategy offers a promising pathway for high-performance gas separation membranes.