Benzimidazole-Linked Porous Polymers: Synthesis and Gas Sorption Properties

A series of benzimidazole-linked porous polymers are obtained by the condensation reaction between the o-aminobenzol end groups of building blocks (2,3,6,7,10,11-hexaaminotriphenylene, 3,3′-diaminobenzidine or 1,2,4,5-benzenetetraamine) and the aldehyde groups of building blocks [terephthalicaldehyde, 4,4′-biphenyldicarboxaldehyde, 1,3,5-tris(4-acetylphenyl)benzene or 1,3,5-tris(4-formylbiphenyl)amine] in one-pot synthesis without employing any catalyst or template. The existence of the imidazole ring in the obtained polymers could be identified by Fourier transform infrared and solid-state ¹³C CP/MAS NMR spectroscopy. The sphere-shaped morphology of the obtained polymers is observed through scanning electron microscopy. The polymers possess Brunauer-Emmett-Teller specific surface area values over 600 m²·g⁻¹, showing hydrogen storage (up to 1.6 wt%, at 77 K and 1×10⁵ Pa) and carbon dioxide capture (up to 12.6 wt%, at 273 K and 1×10⁵ Pa) properties. Such polymers would possess good performance in the applications of gas storage and separation.