Highly efficient triptycene-based hypercrosslinked polymers (HCPs) for selective CO₂ capture

Carbon dioxide (CO₂), the primary anthropogenic greenhouse gas, is a major contributor to global climate change, necessitating the development of efficient adsorbents for carbon capture. In this work, two nitrogen-rich microporous hypercrosslinked polymers (HCPs), TP-Cz HCP and TP-DPA HCP, were synthesized via a simple Friedel–Crafts polymerization of triptycene with carbazole and diphenylamine, respectively. The rigid triptycene framework endowed the polymers with high surface area, permanent microporosity, and excellent thermal stability, while the nitrogen-containing units enhanced their affinity toward CO₂. The polymers were comprehensively characterized by spectroscopic, microscopic, thermal, and surface analyses. Density functional theory (DFT) calculations further revealed that the nitrogen-rich framework provides energetically favorable adsorption sites for CO₂, supporting the experimental adsorption results. Among the synthesized materials, TP-Cz HCP exhibited a high CO₂ uptake of 3.72 mmol g⁻¹ at 273 K and 2.25 mmol g⁻¹ at 298 K, along with an isosteric heat of adsorption of 30.62 kJ mol⁻¹ and an excellent CO₂/N₂ selectivity of 223. Dynamic breakthrough experiments under dry and humid conditions, along with adsorption–desorption kinetic and cycling studies, demonstrated rapid CO₂ uptake, excellent regeneration stability, and outstanding moisture tolerance. These findings highlight the great potential of triptycene-based nitrogen-rich HCPs as robust adsorbents for practical post-combustion CO₂ capture and selective gas separation.