Low-cost multifunctional antimony-doped tin oxide/polyacrylamide-chitosan double-network hydrogels with good mechanical properties and excellent electromagnetic interference shielding performance in terahertz band

Abstract

Researchers have recently developed various methods to incorporate conductive fillers into hydrogel matrices, including metal-based fillers, carbon nanotubes, and two-dimensional materials like MXenes, significantly enhancing their electromagnetic interference (EMI) shielding properties. However, due to the high cost of these fillers, balancing the high EMI shielding (SE), excellent mechanical performance, and low production costs remains a significant challenge, hindering the widespread industrial application of such hydrogels. In this study, we fabricated antimony-doped tin oxide (ATO)/polyacrylamide (PAAm)-chitosan (CS) hydrogels using sodium citrate (Cit) for salting-out, forming double networks and molecular entanglement. The introduction of ATO and the salting-out effect of Cit not only endowed the hydrogel with excellent mechanical properties (strength > 1.5 MPa) but also enhanced its conductivity and EMI shielding effectiveness while maintaining overall low production costs. The hydrogel achieved a 60.2 dB of EMI SE in the 0.1–1.0 THz range, with the price per milliliter of conductive filler being approximately 0.2 % of that in hydrogels incorporating MXenes or reduced graphene oxide. Notably, the hydrogel also demonstrated excellent strain-sensing capabilities. Combining the outstanding properties above, the gel presents a promising candidate for next-generation flexible electronic device shielding applications. It has significant potential for industrial adoption as a cost-effective EMI shielding material.