Porous Polybenzimidazoles via Template-Free Suzuki Coupling Polymerization: Preparation, Porosity, and Heterogeneous Catalytic Activity in Knoevenagel Condensation Reactions

Suzuki coupling polymerization between boronic acids and halo-benzimidazole provides a new alternative approach to prepare polybenzimidazoles. PPBIs (PPBI-1 and PPBI-2) with porous structures are prepared through a template-free synthetic route. The BrunauerEmmettTeller specific surface areas for PPBI-1 and PPBI-2 are 385 and 158 m2 g-1, respectively. Based on the hydrogen physisorption isotherms measured at 77 K and a pressure up to 1.13 bar, PPBI-1 exhibits a hydrogen uptake of 0.83 wt% at 1.13 bar and 77 K. An increase in the carbon dioxide loading capacity with increasing specific surface area is observed, in which PPBI-1 shows higher carbon dioxide uptake (8.0 wt%) than PPBI-2 (6.1 wt%) at 1.0 bar and 273 K. Additionally, the prepared PPBIs can act as a heterogeneous catalyst for Knoevenagel reaction.