Dendrimer-like conjugated microporous polymers

Four dendrimer-like polycarbazole conjugated polymer networks P-G1-T, P-G2-T, P-G1-Fo and P-G2-Fo were designed and synthesized by FeCl3 oxidative coupling polymerization. Aromatic thiophene and fluorenone units were employed as the linkers between carbazole units to construct the building blocks. The first generation polymers (1st) were produced from the monomers containing two carbazole units, while the second generation polymers (2nd) were produced from the monomers with six carbazole units, which feature double oxidative polymerization sites compared with the monomers for the 1st generation. It was found that the 2nd generation polymers show a higher Brunauer–Emmett–Teller (BET) surface area and a higher gas adsorption performance than the 1st generation polymers because of more reactive sites and larger torsion angles in the monomers for the 2nd generation, which led to a highly crosslinked polymer structure and thus a high surface area. All of the polymers show high isosteric heats of CO2 adsorption over 33 kJ mol−1 because the incorporation of heteroatoms (N, S and/or O) into the skeleton of the polymers enhanced the interaction between the pore wall and CO2 molecules.