Shape memory composite membrane with widely programmable electromagnetic shielding effectiveness

The application of shape memory smart materials in the field of electromagnetic interference (EMI) shielding can compensate for their poor adaptability and promote the development of electromagnetic shielding composite materials towards multi-functionality and intelligence. Herein, an intelligent poly(ethylene-co-vinyl acetate)/polydopamine/MXene (EVA/PDA/MXene) composite membrane with tunable electromagnetic shielding capability over a wide range was prepared using electrospinning and dip-coating techniques. Firstly, electrospinning technology was used to prepare highly cross-linked EVA fiber membranes. Secondly, the surface of these membranes was modified with dopamine. And finally, dip-deposition technology was employed to tightly attach MXene nanosheets to the surface of the modified membranes. The electromagnetic shielding effectiveness of the EVA/PDA/MXene-30-6 composite membrane in the X-band (8.2-12.4 GHz) is up to 74.7 dB, and both the shape fixation rate (R_f) and shape recovery rate (R_r) are above 90%. Most importantly, it achieves a reversible tuning of shielding effectiveness from 26.2 dB to 74.7 dB under a tensile strain of 0-30%. Furthermore, the electromagnetic shielding effectiveness of the composite membrane remains virtually unchanged after undergoing continuous bending and folding, and its surface temperature can reach 93.2 °C when subjected to a voltage of 2.5 V, thereby demonstrating exceptional electro-thermal conversion capability. This multifunctional composite membrane, characterized by its adaptability, provides a direction for the development of electromagnetic shielding composites.