Multi‐Armed Molecule Drives High Energy Dissipation and Stiffness via Physically Cross‐Linking

Abstract Damping materials, particularly viscoelastic polymeric materials, are essential to mitigate or even eliminate vibration through energy dissipation. However, designing pure polymeric damping materials with high stiffness remains a challenge, which limits their application in constrained damping layer treatments for mechanical structures. Herein, a chemical design of damping yet stiff supramolecular polymeric materials (SPMs) cross‐linked by small dendritic molecules with quadruple H‐bonding units at the branch ends is proposed. These rationally designed molecules not only enhance the chain relaxation and improve the damping performance of the original polymeric topology, but also maintain the resultant stiffness at a high level due to newly generated robust quadruple H‐bonds. As a result, these SPMs exhibit excellent damping performance across a wide range of frequencies and temperatures, while simultaneously demonstrating key constrained damping characteristics such as high stiffness, adhesive properties, and recyclability. Importantly, these SPMs are employed as a model system to elucidate the molecular mechanism underlying their unique combination of damping and stiffness.