Flexible multifunctional Janus film towards self-healing, self-adhesive and streachable EMI shielding.

As smart electronic devices proliferate rapidly, concerns about electromagnetic radiation have become more prominent. Traditional electromagnetic shielding materials typically use three-dimensional porous foams, carbon structures, and film materials as their substrates. However, as electronic devices become more miniaturized, integrated, and precise, the large volume and limited functionality of foam materials have constrained their applications. Therefore, developing a compact, lightweight, and multifunctional electromagnetic shielding material has become a pressing need. In this study, we prepared an adhesive-free, stretchable, and self-healing multifunctional electromagnetic shielding material called PHST@AgNW. The introduction of polydimethylsiloxane (PDMS) provides PHST with excellent toughness, imparting stretchability to the film. Covalent crosslinking between catechol groups and substrates enables rapid adhesion to various surfaces. Additionally, hydrogen bonds and dynamic disulfide bonds endow PHST with outstanding self-healing properties. By incorporating silver nanowires (AgNW) as a conductive layer on the surface of PHST, we fabricated the PHST@AgNW electromagnetic shielding film. Notably, when the surface density of AgNW reaches 4 g/m, the electromagnetic interference shielding effectiveness (EMI SE) reaches 58 dB. After three cycles of repeated adhesion, the EMI SE performance remains almost unchanged. Ag-S bonds enable the material to maintain excellent EMI SE performance even under 50 % tensile strain. Furthermore, after self-healing, the PHST@AgNW film's electromagnetic shielding performance rapidly recovers to 99.9995%, showcasing its broad application potential in areas requiring resistance to deformation and damage.