Effect of structure and functionality on the performance of triptycene-heteroaromatic porous polymers for selective CO₂ capture

This work reports the synergistic effect of tuning the structure and functionality of triptycene-heteroaromatic porous organic polymers toward selective CO₂ capture. The polymers were constructed by a rapid and energy-efficient microwave-assisted Friedel-Crafts polymerization of triptycene with heteroaromatic units of pyrrole, furan, and thiophene using dimethoxymethane (DMM) as a linker and FeCl₃ as a catalyst. The resulting materials exhibit robust thermal stability and high BET surface areas, reaching up to 1316 m²/g. Gas sorption studies confirmed the polymers' potential, demonstrating significant CO₂ uptake (up to 2.81 mmol g⁻¹ at 273 K) and high selectivity for CO₂ over N₂ and CH₄, reaching a selectivity of CO₂/N₂ up to 238 and a selectivity of CO₂/CH₄ up to 24. The research establishes that the incorporation of different heteroatoms (N, O, S) provides an effective strategy for tuning the polymers' adsorption properties, highlighting the synergistic effect of triptycene's space-generating structure and the electronic functionalities and loading of the heteroaromatic units on the overall structure and performance of the polymer.