Flexible, optically transparent and self-healing ionogels for microwave/infrared dual-band stealth

Abstract

Despite the significant progress in microwave absorption materials (MAMs) for electromagnetic shielding, developing absorbers that are compatible with transparent electronics remains a critical challenge. While functionalities such as self-healing, flexibility, and transparency have been individually demonstrated in MAMs, conventional absorbers limit their further integration. Herein, a multifunctional MAM is created by the in situ incorporation of an ionic liquid (IL) into polyurethane (PU). It exhibits 97.58% transmittance and ultrahigh tensile strain capability (1433.79%). Notably, the ultra-high IL content (90%) and dynamically cross-linked network enable the synergistic effect of dielectric polarization relaxation, ionic conduction loss and self-healing ability. Consequently, iPU-90 achieves a minimal reflection loss (RL_min) of −40.98 dB at a thickness of 4.0 mm and efficient absorption in the X-band, alongside a remarkable self-healing efficiency of 94.38% for mechanical properties and 98.07% for EMW absorption. In addition, the dynamic evolution of electromagnetic wave absorption performance throughout self-healing is systematically investigated. Furthermore, a multi-band microwave stealth metasurface is fabricated from the ionogel via membrane transfer, integrating microwave absorption and infrared stealth, demonstrating effective self-healing. Overall, this work presents an effective strategy for fabricating transparent MAMs with self-healing ability, which expands the feasibility boundary for interdisciplinary applications.