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Isomeric Aromatic Polyimides Containing Biphenyl Moieties for Gas Separation Applications
Laura Matesanz-Niño1,2,3, David Cuellas1, Carla Aguilar-Lugo4
1Department of Macromolecular Chemistry, Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain.
Polymers
|March 29, 2023
Summary
High molecular weight aromatic polyimides were synthesized for gas separation. The resulting membranes exhibit high gas productivity and good mechanical properties for high-pressure applications.
Area of Science:
- Polymer Chemistry
- Materials Science
- Chemical Engineering
Background:
- Aromatic polyimides are crucial for gas separation membranes due to their thermal stability and mechanical strength.
- Monomer structure significantly influences polymer chain packing and gas transport properties.
- Optimizing synthesis and processing is key to achieving high-performance polymeric membranes.
Purpose of the Study:
- To synthesize high molecular weight aromatic polyimides using an optimized monomer.
- To investigate the structure-property relationships of these polyimides for gas separation.
- To evaluate the performance of derived membranes in high-pressure gas purification.
Main Methods:
- Optimized synthesis of 2,2'3,3'-biphenyltetracarboxylic dianhydride (iBPDA) monomer.
- Polymerization of iBPDA with 2,2-bis(4-aminophenyl) hexafluoropropane (6FpDA) diamine.
- Thermal treatment of polymer membranes above glass transition temperature (350 °C) for complete imidization and solvent removal.
- Characterization of polymer properties and membrane performance for gas separation.
Main Results:
- High molecular weight aromatic polyimides with contorted structures were successfully synthesized.
- The polymers exhibited hindered chain packing due to the non-linear monomer shape and rigid diamine groups.
- Dense membranes processed via thermal treatment showed complete imidization and solvent elimination.
- The membranes demonstrated high gas productivity and good mechanical properties suitable for high-pressure applications.
- Polymer models indicated Arrhenius-like behavior characteristic of secondary relaxations.
Conclusions:
- The optimized synthesis of iBPDA and its polymerization with 6FpDA yield high-performance polyimides for gas separation.
- The contorted structure of iBPDA and the rigidity of 6FpDA contribute to favorable membrane properties.
- Thermal processing is critical for achieving optimal imidization and membrane performance.
- These materials are promising for high-pressure gas purification applications due to their mechanical integrity and high gas productivity.
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