A High-Throughput Preparation Strategy for Microporous Polyimides and Their Photocatalysis Performance: Understanding Polymerization Kinetics and Thermodynamics in a Solvothermal System

Due to the characteristics of step polymerization, high monomer conversion and polymerization degree cannot be achieved simultaneously for polyimides. In our recent report, naphthalene-based microporous polyimides (MPIs) have been successfully prepared in 30 min with superior surface area and yield to their documented counterparts, benefiting from the improved solvothermal method developed by our group [Zhu et al. Green Chem. 2020, 22, 7003]. Inspired by the factor-optimizing protocol, we realize that some neglected polymerization parameters probably have a significant influence on the seemingly simple polymerization process. In this article, the detailed investigation indicates that either increasing the reaction temperature or decreasing the monomer content can effectively prohibit the early desolvation and phase separation during polymerization, resulting in the formation of long-range interpenetrating polymer networks. Eventually, five families of MPIs, totaling 15 samples, with high surface area were produced with the aid of the optimized polymerization parameters in 1.5 h, starting from commercially available dianhydride (or tetracid) and triamine monomers. Particularly, the maximum surface area of perylene-based MPIs achieves 447 m2 g–1. They can work as photocatalysts to produce H2O2 with a rate of 2195 and 2240 μmol g–1 h–1 under visible light (>420 nm) and simulated sunlight irradiation, respectively.