Highly stretchable and strain-insensitive multilayered electromagnetic interference shielding films prepared via a simple soaking-infiltration strategy

Stretchable electromagnetic interference (EMI) shielding films are crucial for wearable electronics. However, it is challenging to further endow the EMI shielding films with good stretchability and satisfactory EMI shielding effectiveness (EMI SE) under large strains. Herein, we successfully prepared high-performance stretchable polydimethylsiloxane (PDMS)/single-walled carbon nanotube buckypaper (SWNT BP)/PDMS EMI shielding films with multi-graded conductive networks via a soaking-infiltration strategy. In this multilayered film, infiltration layers of SWNT/PDMS were particularly created between elastic PDMS and brittle SWNT BP. Owing to the multilayered structure and conductivity compensation effects arising from infiltration layers, our EMI shielding films exhibited excellent EMI SE of 34.2 dB with high stretchability of >400 %. The outstanding EMI SE could be well maintained under large strains. At <50 % strain, the relative change in EMI SE (|ΔSE/SE₀|) remained consistently below 10 %, while at even 100 % strain, |ΔSE/SE₀| was only ∼35 %. Furthermore, we proposed a parallel-series hybrid model to describe electrical conduction in straining films. Due to their excellent conductivity under strain, the films could also serve as stretchable Joule heaters. This work provides a novel and simple approach for constructing strain-insensitive conductive films, with potential applications in stretchable EMI shielding and thermal management.