Design of dual-network structure based on coordination bonds and hydrogen bonds for high-performance multifunctional flexible gel absorbers

The emergence of precision electronic devices and wearable electronic products urgently requires high-performance multifunctional electromagnetic wave (EMW) absorbers to meet the applicability and versatility in various applications. Herein, a dual-network (DN) gel was successfully prepared using acrylamide and sodium lignosulphonate as the basic units by simple chemical cross-linking and physical cross-linking methods. Specifically, the hydrogel forms two types of cross-linking networks through metal coordination and hydrogen bonding. Benefiting from the combined effects of dipole polarization and conductivity loss, the gel achieves an effective absorption bandwidth (EAB) of 6.74 GHz at a thickness of only 1.89 mm, demonstrating excellent EMW absorption performance. In addition, this unique structural configuration endows the EMW absorber with multifunctional features, such as remarkable tensile strength, good environmental compatibility, ultraviolet (UV) resistance, and excellent adhesion. Integrating multiple functional features into the EMW gels displays a broad application prospect in a variety of application scenarios. This research reveals the significance of DN structure design in the electromagnetic wave absorption (EWA) performance of gel-based materials, providing a substantial foundation for the multifunctional design of gel-based absorbers.