Hierarchical porous 4-bromoaniline based hypercrosslinked polymers for CO₂ capture

Hypercrosslinked polymers (HCPs) show a scalable family of porous materials that are ideal for post-combustion CO 2 capture. This study reports two HCPs based on 4-bromoaniline (HCP-BA-A and HCP-BA-B), synthesized via FeCl₃-catalyzed Friedel–Crafts alkylation, which produce durable networks featuring hierarchical micro and mesoporosity. The material’s architecture and morphology are verified through FTIR, SEM, and TEM, while N 2 adsorption–desorption isotherms support the porous structure. These HCPs achieve BET surface areas (919.08 m 2  g⁻ 1 for HCP-BA-A; 753.42 m 2  g⁻ 1 for HCP-BA-B), good CO₂ uptakes (HCP-BA-A: 4.24 mmol g⁻ 1 at 273 K/1 bar, 2.82 mmol g⁻ 1 at 298 K/1 bar; HCP-BA-B: 3.06 mmol g⁻ 1 at 273 K/1 bar, 1.98 mmol g⁻ 1 at 298 K/1 bar), low isosteric heats of adsorption (28–32 kJ mol⁻ 1 ), and excellent cyclability (> 95% retention after multiple cycles). The kinetics follow a pseudo-1st order model, indicating rapid, surface-dominated uptake, and the adsorption isotherms most closely match the Langmuir–Freundlich model, reflecting heterogeneous surface energies. These HCPs outperform a variety of conventional porous sorbents because of inexpensive synthesis from accessible aromatic compound, straightforward scalability and enhanced hierarchical porosity. Graphical abstract