A polymer sponge with dual absorption of mechanical and electromagnetic energy

Polyaniline, a modified conductive polymer, has been widely studied in the field of electromagnetic (EM) wave absorption due to its excellent dielectric and conductive properties. However, it has limited applications due to its hard molding and processing, and poor mechanical stability. In this study, ice crystals with rapid directional growth were used as templates for polymerization to obtain polymer precursors with directional channels, and then ternary polymer sponges with oriented pore channels were designed and synthesized using a secondary template method. The Poisson's ratio of the study material reaches -1.52 and it absorbs 5.1 mJ/cm³ energy in a single compression cycle at 25% longitudinal strain. Also, the material has more than 90% absorption efficiency for X-band EM waves at a thickness of 4 mm. The flexibility of polymer molecular chains and the arrangement of oriented pores are the reasons for the negative Poisson's ratio property of the material, while the key to the loss of EM energy in the absorption process is the conversion of quinone bipolaron to monopolaron structure. Due to its large-scale green preparation with ice crystal as the template, this lightweight and robust material system are ideal for absorbing EM waves under extreme conditions.