Construction of microporous polycarbozole frameworks for flue gas purification by increasing connected numbers of external linkers

The development of porous adsorbents to address the trade-off between physical adsorption capacity and selectivity has attracted extensive research interest due to their potential applications in gas separation and purification, but remains a daunting challenge. Herein, we report a new strategy involving increasing connected numbers of external linkers (from di-connected DCM to tri-connected TCM) to crosslink nitrogen-rich carbazole derivatives, thereby improving the microporosity of microporous polycarbozole frameworks and promoting CO2 adsorption capacity and selectivity. This is mainly attributed to tri-connected linker can make carbazole-based monomers more closely packed than di-connected linker, resulting in higher microporosity in tri-connected polymers constructed from the same monomer than that of di-connected polymers. Meanwhile, the dynamic breakthrough experiments show that tri-connected polymers have better CO2/N2 separation abilities than di-connected polymers. Construction of microporous polycarbozole frameworks by increasing connected numbers of external linkers to address the trade-off between CO2 adsorption capacity and selectivity. [Display omitted] •Provided a strategy to address the trade-off between adsorption capacity and selectivity.•Increasing connected numbers of external linkers can improve the microporosity of the polymer.•Tri-connected polymers have better CO2/N2 separation abilities than di-connected polymers.