One-step preparation of hierarchically porous polyureas: Simultaneous foaming and hyper-crosslinking

Abstract A series of hierarchically structured porous polyureas are prepared through the polymerization of diisocyanate monomers and H 2 O via a one-step and template-free strategy. This simple archetypal reaction combines carbon dioxide foaming process and hyper-crosslinking reaction. The obtained hierarchically porous polyureas (HPUs) consist of micro- and mesopores created by hyper-crosslinking reaction, and macropores generated by carbon dioxide foaming process. The HPUs have a high surface area up to 483.3 m 2 /g, and large pore volume (0.76 cm 3 /g). Besides, the nitrogen-doped carbon materials prepared by pyrolyzing the HPUs show a high specific capacitance (209 F/g at 1.0 A/g) and good cycling stability (99.8% capacitance retention after 5000 cycles), demonstrating the advantages of the hierarchically porous structure and nitrogen-rich chemical composition of HPUs.