PEEK-WC-Based Mixed Matrix Membranes Containing Polyimine Cages for Gas Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Science

Background:

• Membrane-based gas separations are crucial for sustainable and energy-efficient processes.
• Mixed matrix membranes (MMMs) enhance polymer performance by incorporating filler materials.
• Poly(ether ether ketone) with cardo group (PEEK-WC) is a promising polymer matrix for membranes.

Purpose of the Study:

• To investigate the effect of different organic cages as fillers in PEEK-WC for gas separation.
• To evaluate the influence of filler dispersion and type on membrane performance and properties.
• To compare experimental results with theoretical models like the Maxwell model.

Main Methods:

• Dispersing four different organic cages (m-xylyl imine, furanyl imine, p-xylyl imine, diphenyl imine) into a PEEK-WC polymer matrix.
• Fabricating mixed matrix membranes (MMMs) and applying a silicone coating.
• Measuring pure gas permeability (H2, He, O2, N2, CH4, CO2) and calculating diffusion coefficients using time-lag measurements.

Main Results:

• MMMs with m-xylyl imine and furanyl imine cages showed mechanical robustness and selectivity after silicone coating.
• Poor dispersion of p-xylyl imine and diphenyl imine cages prevented the formation of selective films.
• Furanyl imine cages increased diffusion of bulkier gases and decreased selectivity, while m-xylyl imine cages slightly increased diffusion and improved size-selectivity.

Conclusions:

• The choice and dispersion of organic cages significantly impact the performance of PEEK-WC based MMMs for gas separation.
• MMMs incorporating well-dispersed organic cages offer a pathway to enhanced gas separation efficiency.
• Careful selection of fillers is critical for achieving desired membrane properties and separation performance.