Highly Durable Silicone‐Based Elastomers Achieved Through the Synergy of Bi‐Incompatible Soft Segments and Multi‐Scale Hydrogen Bonds

Abstract Developing a silicone elastomer with high strength, exceptional toughness, good crack tolerance, healability, and recyclability, poses significant challenges due to the inherent trade‐offs between these properties. Herein, the design of silicone‐based elastomers with a nanoscopic microphase separation structure and comprehensive mechanical properties is achieved by combining bi‐incompatible soft segments and multi‐scale hydrogen bonds. The formation of multi‐scale hydrogen bonds involving urethane, urea, and 2‐ureido‐4[1H]‐pyrimidinone (UPy) facilitates efficient reversible crosslinking of the synthesized polymer containing thermodynamically incompatible poly(dimethylsiloxane) (PDMS) and poly(propylene glycol) (PPG). The dynamic dissociation and recombination of hydrogen bonds, coupled with the forced compatibility and spontaneous separation of bi‐incompatible soft segments, can effectively dissipate energy, particularly in the crack region during the stretching process. The obtained silicone‐based elastomer exhibits a high break strength of 8.0 MPa, good elongation at break of 1910%, ultrahigh toughness of 67.8 MJ m −3 , and unprecedented fracture energy of 31.8 kJ m −2 while maintaining their thermal stability, hydrophobicity, healability, and recyclability. This resilient and long‐lasting silicone‐based elastomer exhibits significant potential for use in flexible electronic devices.