Multifunctional shape memory foam composites integrated with tunable electromagnetic interference shielding and sensing

Porous polymer-based conductive composites are highly regarded for their accomplishments of being applied in the field of electromagnetic interference (EMI) shielding, but fabrication of high-performance porous EMI shielding materials with the ability to realize self-fixable shielding effectiveness (SE) adjustment is still challenging. Herein, ethylene–vinyl acetate copolymer (EVA)@polypyrrole (PPy)@Ag (EPA) foam composites are fabricated by modifying EVA foams with PPy and Ag nanoparticles (AgNPs) in succession. In this system, EVA foam serves as shape memory frameworks to endow this composite with shape memory effect (SME), and PPy is employed to reinforce the interaction between the Ag layers and the EVA foam. Profiting from the reinforced conductive network, the EPA foam composites exhibit electro-thermal performance with a heating temperature of 81.1 °C at a voltage of 1 V and EMI shielding performance with a SE of 107.45 dB within the X-band. Importantly, depending on the SME, the SE of the EPA foams can be easily tuned by controlling and fixing the compressive strain. Moreover, the EPA foams can also serve as sensors for monitoring different actions. By virtue of the above merits, the EPA foams are promising to serve as multifunctional electronics, involving smart EM protection devices and wearable sensors.