Lightweight and stiff carbon foams derived from rigid thermosetting polyimide foam with superior electromagnetic interference shielding performance

Carbon foams are obtained by pyrolysis of conventional polymeric porous materials usually show poor mechanical properties. The preparation of lightweight carbon foams with high mechanical strength and adjustable three-dimensional architecture still remains a huge challenge. This work reports an efficient approach for fabricating rigid carbon foams via carbonization of thermosetting polyimide foam. Benefiting from the cross-linked networks, the prepared carbon foams present excellent thermal and dimensional stability with low shrinkage of ∼47% after carbonized at 1500 °C. Moreover, the compressive strength of the carbon foams after carbonized at 1200 °C (CF-1200) reaches 0.25 MPa at 10% strains with the density of 0.091 g cm⁻³. Notably, the CF-1200 shows superior electromagnetic interference (EMI) shielding effectiveness and specific EMI shielding effectiveness of ∼54 dB and 593.4 dB cm³/g respectively at 10 GHz with the thickness of 2.0 mm. In particular, the bulk density, mechanical properties, electrical conductivity of carbon foams can be adjusted by varying the characteristics of polyimide foam accordingly. As the result, these lightweight and stiff carbon foams with such superior EMI SE have great potential applications as structural-functional integrated materials in the aerospace and wireless telecommunication fields.