Polymeric electromagnetic interference (EMI) shielding foaming materials are found and applied in many frontier fields such as aerospace, transportation, and portable electronics. In this paper, a foam based on a composite system of poly(vinylidene fluoride) (PVDF) filled with carbon nanotubes (CNTs) is prepared for EMI shielding properties by using a solid‐state supercritical CO2 foaming strategy. PVDF is chosen as the matrix because of its excellent chemical resistance, thermal stability, and flame retardancy. The inclusion of CNTs renders this composite system enhanced complex viscosity and storage modulus by about two orders of magnitude. The electrical conductivity and EMI specific shielding effectiveness of obtained foams can be adjusted and reached the optimum value of 0.024 S m−1 and 29.1 dB cm3 g−1, respectively, originating from the gradual development of interconnected CNTs and conductive CNTs network as well as the introduction of cell structure in PVDF matrix. Interestingly, the reorientation of CNTs caused by foaming process results in electrical conductivity percolation threshold of PVDF/CNTs foams markedly decreases, in comparison to their unfoamed samples. This study provides a facile, efficient, green, and economic route for the preparation of EMI shielding foams consisted of fluorinated polymers and carbonaceous fillers.

Driven by rapidly growing demands in fields such as mobile electronics, aerospace and military, the need for functional materials with lightweight, good environmental stability and efficient electromagnetic interference (EMI) shielding properties has rose sharply. In this paper, quaternary nanocomposite foams comprising of poly(vinylidene fluoride) (PVDF), carbon nanotubes (CNTs), graphene nanoplatelets (GNPs) and Ni were developed by a melt blending and supercritical CO2 foaming technology. Compared with pure PVDF, the crystallization temperature of PVDF/2CNTs/2GNPs/12Ni nanocomposite increased remarkably from 139.0 to 144.9°C. Rising the nanofiller loading from 0 to 16 wt% led to the enhancements of around four orders of magnitude in the storage modulus of PVDF nanocomposites as well as about three orders of magnitude in their complex viscosity. For a typical PVDF/2CNTs/2GNPs/12Ni nanocomposite, its EMI shielding effectiveness reached 32.2 dB, brought by dielectric loss and magnetic loss. The electrical conductivity and EMI shielding effectiveness of PVDF nanocomposite foam achieved the optimum values of 0.84 S/m and 19.4 dB, respectively, which originated from the introduction of pore structure and the gradual generation of nanofiller‐nanofiller conductive networks. This study took a promising way toward the fabrication of materials with adjustable EMI shielding property in the fields of electronics and aerospace industries.

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