Facile Preparation of Dibenzoheterocycle-Functional
Nanoporous Polymeric Networks with High Gas Uptake Capacities
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Abstract
A consolidated
ionothermal strategy was developed for the polymerization
of thermally unstable nitriles to construct high performance materials
with permanent porosity, and carbazole, dibenzofuran, and dibenzothiophene
were separately introduced into covalent triazine-based networks to
investigate the effects of heterocycles on the gas adsorption performance.
Three nitriles, namely 3,6-dicyanocarbazole, 3,6-dicyanodibenzofuran,
and 3,6-dicyanodibenzothiophene, were designed and synthesized, which
were readily converted to heat-resistant intermediates at a moderate
temperature and then polymerized to create highly porous poly(triazine)
networks instead of the traditional one-step procedure. This documents
an improved strategy for the successful construction of heterocyclic-functional
triazine-based materials. The chemical structures of monomers and
polymers were confirmed by <sup>1</sup>H NMR, FTIR, and elemental
analysis. Such polymers with high physical–chemical stability
and comparable BET surface areas can uptake 1.44 wt % H<sub>2</sub> at 77 K/1 bar and 14.0 wt % CO<sub>2</sub> at 273 K/1 bar and present
a high selectivity for gas adsorption of CO<sub>2</sub> (CO<sub>2</sub>/N<sub>2</sub> ideal selectivity up to 45 at 273<i>K</i>/1.0 bar). The nitrogen- and oxygen-rich characteristics of carbazole
and dibenzofuran feature the networks strong affinity for CO<sub>2</sub> and thereby high CO<sub>2</sub> adsorption capacity. This also helps
to thoroughly understand the influence of pore structure and chemical
composition on the adsorption properties of small gas molecules