Shear‐Stiffening Damping Ionogels Enabled by the Synergy of Dynamic Bonds and Steric Hindrance

ABSTRACT High‐rate impact loading causes structural failure and insufficient energy dissipation in protective materials. The intrinsic stiffness–damping trade‐off in polymer materials makes it highly challenging to simultaneously achieve strong damping and broad frequency energy dissipation. Here, we developed tough ionogels with enhanced shear‐stiffening and damping capabilities through the synergy of dynamic bonds and steric hindrance of hyperbranched polymeric ionic liquids (HPILs). The synergistic coupling of dynamic‐bond dissociation in the high‐frequency regime and the topological constraint of viscous‐flow HPILs in the low‐frequency regime endows the ionogels with broad‐frequency damping and pronounced shear‐stiffening behavior. The prepared ionogel shows an 842‐fold shear‐stiffening response and high damping (tan δ > 1) across a wide frequency range (10 − 3 –10 5 rad s − 1 ). At a high impact rate of 4000 s − 1 , it also exhibits high impact strength (248.6 MPa) and toughness (86.5 MJ m − 3 ). This strategy provides a reference for the design of next‐generation high‐performance damping ionogels.