Polymers with Side Chain Porosity for Ultrapermeable and Plasticization Resistant Materials for Gas Separations

Area of Science:

• Materials Science
• Polymer Chemistry
• Chemical Engineering

Background:

• High-performance polymer membranes are crucial for energy and environmental applications like natural gas purification and carbon capture.
• Existing polymers often rely on rigid backbones, limiting processability and leading to physical aging.
• A need exists for solution-processable polymers with high CO2 permeability and selectivity.

Purpose of the Study:

• To develop and characterize a novel porous polymer for gas separation applications.
• To investigate the structure-property relationships of polymers with flexible backbones and rigid side chains.
• To evaluate the CO2 permeability, selectivity, plasticization resistance, and physical aging of the new polymer.

Main Methods:

• Synthesis of a porous polymer via ring-opening metathesis polymerization.
• Characterization of polymer structure, including flexible backbone and rigid, fluorinated side chains.
• Measurement of gas separation performance, including CO2 permeability, selectivity, plasticization pressure, and aging rates for various gases.

Main Results:

• The synthesized polymer exhibits ultrahigh CO2 permeability (>21,000 Barrer).
• The material demonstrates exceptional resistance to CO2 plasticization (pressure > 51 bar).
• Slower physical aging rates were observed compared to traditional polymers, particularly for small gas molecules like He, H2, and O2.

Conclusions:

• A flexible backbone polymer with rigid, fluorinated side chains provides a promising strategy for advanced gas separations.
• This design overcomes limitations of rigid-backbone polymers, offering enhanced performance and durability.
• The approach is generalizable for creating new polymers for small-molecule separations, with significant implications for carbon capture and natural gas purification.