Ultrathin, flexible and sandwich-structured PHBV/silver nanowire films for high-efficiency electromagnetic interference shielding

Ultrathin, flexible and lightweight characteristics are greatly desirable for next-generation wearable electromagnetic interference (EMI) shielding materials to address EM radiation pollution. Herein, we used poly(3-hydrobutyrate-co-3-hydroxyvalerate) (PHBV), which is a type of biodegradable and non-petroleum-based polymer, and silver nanowires (AgNWs) to fabricate ultrathin and flexible composite films with a sandwich structure via electrospinning, vacuum assisted filtration (VAF) and hot pressing in sequence. Owing to the highly conductive AgNW networks, the minimum sheet resistance and the maximum EMI shielding effectiveness (SE) of the obtained PHBV/AgNW film reached 0.5 Ω sq−1 and 45.9 dB, respectively, in X-band at a thickness of 18 μm. The films could meet the industry-accepted SE requirement (20 dB) at a high optical transparency of 74%. The specific EMI SE (SSE/t) of the film is up to 19 678 dB cm2 g−1, significantly surpassing those of most reported polymeric EMI shielding materials. Moreover, the sandwich structure of the PHBV wrapped AgNW layer could effectively prevent the shedding and corrosion of AgNWs. Thus, the PHBV/AgNW film has an outstanding EMI shielding reliability with a negligible change in EMI SE after exposure to harsh environmental conditions (acidic, alkali and saline solutions) and physical damage (1000 bending cycles and ultrasound for 60 min). This work provides a feasible strategy for the fabrication of ultrathin and flexible EMI shielding films, which will have promising prospects for applications in flexible electronics and wearable devices.