In-situ metallized carbon nanotubes/poly(styrene-butadiene-styrene) (CNTs/SBS) foam for electromagnetic interference shielding

The porous conductive polymer composites have received great attention owing to their superiority of being utilized in electromagnetic interference (EMI) shielding applications. Herein, lightweight and highly compressible conductive composite foam composed of poly(styrene-block-butadiene-block-styrene) (SBS) polymer matrix, carbon nanotubes (CNTs) and silver nanoparticles (Ag NPs) is fabricated by freeze-drying technology, silver precursor absorption and in-situ reduction process. Three-dimensional CNTs conductive network and partially embedded Ag NPs synergistically endow the foam with excellent mechanical, electrical and EMI shielding performance. The flexible 8Ag/4CNTs/10SBS composite foam with a low density of 0.42 g/cm3 exhibits moderate compressive strength of 169.2 kPa at strain of 50%, remarkable conductivity of 753 S/m, and prominent EMI shielding effectiveness (SE) value of around 91 dB in the electromagnetic wave frequency range of 8.2–12.5 GHz. In addition, the 4Ag/4CNTs/10SBS composite foam exhibits robust mechanical–electrical property upon 1000 compression-release cycles at strain of 50%, and its SE value increased by about 33% compared with the initial state after the cyclic compression test. These results suggest that the Ag/CNTs/SBS foams possess promising potential to be used as lightweight, flexible, and high-performance EMI shielding materials in modern electronic devices.