Constructing benzoxazine-containing porous organic polymers for carbon dioxide and hydrogen sorption

Abstract

Two novel benzoxazine-containing porous polymers, BPOP-1 and BPOP-2, have been synthesized by the direct Sonogashira-Hagihara coupling reactions of two brominated benzoxazine derivatives with a tetrahedral silicon-centered monomer. These polymers exhibit high porosity with the highest Brunauer-Emmer-Teller (BET) surface area of 623 m2 g−1 and the highest total pore volume of up to 1.78 cm3 g−1. Porosity comparison with other benzoxazine-containing porous polymers shows that the introduction of tetrahedral silicon-centered units into the porous networks is an efficient strategy to improve the porosity of the final porous polymers. For applications, these polymers possess good carbon dioxide uptakes of up to 1.79 mmol g−1 (7.9 wt%) at 273 K and 1.0 bar, a comparably high binding ability with CO2 with an adsorption enthalpy of up to 29.6 kJ mol−1, as well as a moderate hydrogen uptake of up to 5.87 mmol g−1 (1.12 wt%) at 77 K and 1.0 bar. These values are comparable to or higher than other porous polymers with a level of surface areas and previously reported benzoxazine-containing porous polymers, thereby suggesting their potential applications as efficient solid absorbents for storing CO2 and H2.