Design of lightweight silicone rubber composite foam with strong electromagnetic shielding effectiveness based on gradient structure

Abstract The popularity of foam and wearable electronic materials requires lightweight materials with high electromagnetic interference (EMI) shielding performance. Silicone rubber foam is a lightweight, compression‐shrinkable, porous polymer that fulfills this need. In this work, a simple and easy‐to‐process operation mode was proposed. The silicone rubber/calcium carbonate (CaCO 3 )@stearic acid (SA)/multi‐walled carbon nanotubes (MWCNTs)@γ‐aminopropyl triethoxysilane (KH550) EMI shielding composite conductive foam with a lightweight gradient structure was prepared. The layered material is divided into three layers: A, layer of lightweight foam; B, layer of bonding; and C, layer of conductive. A layer reduces density; C layer provides strong electromagnetic (EM) shielding; B layer eliminates defects and achieves tight adhesion between layers. Gradient foam material is light has high compression, and has strong EM shielding, with a density of 0.500 g/cm 3 , a directional tensile strength of 1.72 MPa, a compressive strength of 0.71 MPa, and an EM shielding value of 43.26 dB. Subsequent studies showed that the EMI shielding effectiveness (SE) value of gradient foam materials increased with the increase of conductive layer thickness, reaching 85.10 dB at 3.0 mm. This is attributed to the aspect ratio structure of MWCNTs, which can construct a three‐dimensional conductive network at low content and thin thickness. This material is lightweight and has high EM shielding performance, with broad application prospects in the fields of seismic and pressure reduction, EMI resistance, and other valuable instruments. Highlights Preparation of low‐cost foam materials filled with calcium carbonate. Filling of MWCNTs to form an ideal three‐dimensional conductive network. Introduction of an adhesive layer to better bond the foam layer to the conductive layer. Build a three‐layer structure to enhance EMI performance.