Solid state chemical transformation provides a fully benzoxazine-linked porous organic polymer displaying enhanced CO₂ capture and supercapacitor performance

In this study, we synthesized a fully benzoxazine (BZ)-linked porous organic polymer (POP) comprising triphenylamine (TPA) and dihydroxyterephthalaldehyde (DHPT) units through Sonogashira-Hagihara coupling of TPA- and DHTP-functionalized BZ monomers, prepared through multistep sequences involving the Schiff base formation, reduction, and Mannich reactions. The chemical structure of this fully BZ-linked POP (TPA-DHTP-BZ POP) was validated using Fourier transform infrared (FTIR) and solid-state nuclear magnetic resonance (NMR) spectroscopy. The Brunauer-Emmett-Teller surface area and total pore volume of the TPA-DHTP-BZ POP were 195 m² g⁻¹ and 0.53 cm³ g⁻¹, respectively. The poly(TPA-DHTP-BZ) POP showed an impressive CO₂ capture performance of 3.29 mmol g⁻¹ and a specific capacitance of 67.1 F g⁻¹ at 0.5 A g⁻¹. After thermal ring-opening polymerization, a solid-state chemical transformation, the resulting poly(TPA-DHTP-BZ) POP featured Mannich bridges and phenolic groups that formed strong inter- and intramolecular hydrogen bonds, thereby enhancing the electrochemical and CO₂ capture properties. Therefore, poly(TPA-DHTP-BZ) POP has the potential to be employed in practical applications for CO₂ capture and as an efficient electrode for energy storage.