A rational construction of microporous imide-bridged covalent-organic polytriazines for high-enthalpy small gas absorption

A series of microporous imide functionalized 1,3,5-triazine frameworks (named TPIs@IC) were designed by an easy-construction technology other than the known imidization method for the construction of porous triazine-based polyimide networks (TPIs) with the same chemical compositions. In contrast to TPIs, TPIs@IC exhibit much higher Brunauer-Emmett-Teller (BET) surface areas (up to 1053 m(2) g(-1)) and carbon dioxide uptake (up to 3.2 mmol g(-1)/14.2 wt% at 273 K/1 bar). The presence of abundant ultramicropores at 5.4-6.8 angstrom, mainly ascribed to a high-level cyano cross-linking, allows the high heat absorption and high selective capture of CO2. The Qst (CO2 esoteric enthalpies) from their CO2 adsorption isotherms at 273 and 298 K are calculated to be in the range 46.1-49.3 kJ mol(-1) at low CO2 loading, and the ideal CO2/N-2 separation factors are up to 151, exceeding those of the most reported porous organic polymers to date. High storage capacities of TPIs@IC for other small gases like CH4 (5.01 wt% at 298 K/22 bar) and H-2 (1.47 wt% at 77 K/1 bar) were also observed, making them promising adsorbents for gas adsorption and separation.