Hydrothermal polymerization of porous aromatic polyimide networks and machine learning-assisted computational...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Polyimides (PI) are high-performance polymers known for thermal stability.
• Traditional PI synthesis often involves harsh conditions and solvents.
• Developing greener and more efficient PI synthesis methods is crucial.

Purpose of the Study:

• To report the hydrothermal polymerization (HTP) of polyimide networks using water as a medium.
• To investigate the properties, morphology, and scalability of the synthesized PI materials.
• To establish a solvent-free route for PI production.

Main Methods:

• Hydrothermal polymerization of 1,3,5-tris(4-aminophenyl)benzene (TAPB) and pyromellitic acid (PMA) in water.
• Characterization using low-pressure gas physisorption and Hg intrusion porosimetry.
• Morphological analysis via scanning electron microscopy (SEM) and computational image analysis.
• Upscaling of synthesis and solvent-free warm-pressing for material processing.

Main Results:

• Achieved full polyimide condensation in 2 hours at 200 °C, yielding thermally stable monoliths (>500 °C, up to 595 °C).
• Synthesized PI monoliths exhibit hierarchical porosity with a high specific pore volume (7250 mm³ g⁻¹).
• Identified eight distinct morphologies and proposed a formation mechanism based on SEM analysis and computational tools.
• Successfully upscaled the process and produced dense cylindrical specimens without harmful solvents.

Conclusions:

• Hydrothermal polymerization offers an efficient and green method for synthesizing high-performance polyimide networks.
• The resulting PI materials possess unique hierarchical porosity and excellent thermal stability.
• This study presents a viable solvent-free pathway for the large-scale production of advanced polyimide materials.