Microporous Functionalized Triazine-Based Polyimides with High CO₂ Capture Capacity

Porous organic polymers with polar surfaces are promising materials for capture and storage applications for carbon dioxide. Here, we present the synthesis and characterization of seven triazine-based porous polyimide (TPI) polymer networks and evaluate their applicability as CO₂ sorbent materials. The TPIs were synthesized in good yields by a condensation reaction of 2,4,6-tris­(4-aminophenyl)-1,3,5-triazine (TAPT) and the respective dianhydride building blocks in <i>m</i>-cresol. The resulting TPI polymer networks exhibited high chemical and thermal stability under air (up to 450 °C). Argon sorption isotherms demonstrated that specific BET equivalent surface areas up to 809 m² g^–1 (TPI-1) were reached. The characterization of the pore structure revealed mainly micropores with pore diameters ranging from 0.4 to 3 nm. The highest uptake values for CO₂ (2.45 mmol g^–1) were observed for TPI-1 and TPI-2 at 273 K and 1 bar. The highest binding selectivity (56) for CO₂ over N₂ at 298 K was observed for TPI-7. The high degree of functionalization led to comparatively high CO₂ adsorption heats for TPI polymer networks between 29 kJ mol^–1 (TPI-6) and 34 kJ mol^–1 (TPI-1). As a result, the TPI networks showed high CO₂ uptakes relative to their moderate BET equivalent surface areas. In combination with a facile modular synthesis procedure, a high chemical and thermal stability, and the tunability of the CO₂/N₂ binding selectivities, TPIs might be classified as promising materials for CO₂ storage and separation applications