Flexible electrospun carbon nanofibers/silicone composite films for electromagnetic interference shielding, electrothermal and photothermal applications

High-performance conductive films with electromagnetic interference (EMI) shielding, electrothermal, and photothermal properties are highly promising for the development of wearable devices, artificial intelligence, medical care, etc. However, designing such a film with flexibility and toughness remains a challenge. Here, a flexible and multi-responsive composite film for EMI shielding is proposed by coating large-area electrospun carbon nanofiber films (CNFFs) and silicone with an alternating multilayer structure (AMS). The optimal AMS film presents superior EMI shielding (the EMI shielding effectiveness can reach ~ 100 dB with a low thickness of 0.6 mm). Moreover, ultrafast electrothermal response and gratifyingly photothermal performances are also achieved, which can guarantee the normal functioning of AMS films in cold conditions. Furthermore, the outstanding flexibility can be still maintained even after 1000 continuous bending cycles, without worsening the EMI shielding, electrothermal, and photothermal performances. Such superior properties are attributed to the high electrical conductivity, the large specific surface area of carbon nanofibers (CNFs), and strong interface bonding strength, as well as the alternating multilayer structure. Considering the extraordinary performance and the facile preparation method, AMS films show tremendous potential in large-scale applications as advanced EMI protection materials.