Physically crosslinked polyvinyl alcohol hydrogel for electromagnetic shielding

Abstract As military and civilian electronic communication technologies advance rapidly, there is a growing interest in the design and study of high-performance materials for electromagnetic shielding. In marine environments especially, the use of devices like wireless communication, radar, and satellite navigation is common. Hydrogels, a type of porous material, possess characteristics such as low density, high surface area, and exceptional flexibility. Conductive hydrogel materials, which combine the benefits of conductive and hydrogel materials, exhibit conductivity, adjustable mechanical flexibility, and ease of processing. They also have strong electromagnetic wave absorption capabilities. To enhance the effectiveness of electromagnetic shielding in the broadband range of 5-18 GHz, we propose a method to create polyvinyl alcohol hydrogel through physical cross-linking. This involves preparing the hydrogel using the freeze/thaw technique and then physically cross-linking it by submerging it in various salt solutions. Our method significantly improves the electromagnetic shielding effectiveness, with the hydrogel in magnesium chloride solution showing the greatest enhancement in performance, achieving a ~7 dB improvement across different frequencies. The physical cross-linking approach for hydrogel preparation offers the benefits of simplicity and affordability, showcasing a noteworthy electromagnetic shielding effect with promising applications in the field.