Nowadays, electromagnetic pollution has become a serious environmental problem due to the rapid development of electronic products such as mobile phones, computers, and wireless devices. At present, most of the research on electromagnetic shielding materials is focused on enhancing the shielding performance, ignoring the requirements for light weight, heat insulation, corrosion resistance, flexibility and self-cleaning in a complex working environment. Due to the serious increase in electromagnetic pollution and the scarcity of non-renewable resources, the use of renewable biological materials as a substrate to prepare bio-based advanced electromagnetic shielding materials with multi-functional characteristics has become a future trend. Natural wood contains highly anisotropic microchannels, which facilitate the bottom-up transportation of water, ions and other substances to meet the needs of photosynthesis. As a sustainable biomass resource, wood-derived materials have been developed in many new application fields in the past few decades, such as mechanics, catalysis, energy storage, electronics, etc. Here, a top-down method was implemented to selectively remove lignin and hemicellulose to prepare wood aerogel composed almost entirely of cellulose, which were used as substrates for loading aniline monomers. Then, H₃PO₄ and HCl were used as dopants to polymerize aniline in situ. Finally, a hydrophobic flexible electromagnetic shielding composite material was obtained by impregnating PDMS. The three-dimensional porous skeleton inherited from wood is coated with polyaniline to form a conductive network, which has a good shielding performance against electromagnetic waves. Moreover, the material exhibits good flexibility (repeated bending) and has a water contact angle greater than 90°. Hence, as a multifunctional electromagnetic shielding material, it has broad application prospects in electronics, military and other fields.
 

wood; flexible; electromagnetic shielding