A Super-Robust and Ultra-Tough Hydrogel Prepared from Flower-Like Submicron Carbon Clusters Exhibited Excellent Resistance to Crack Propagation.

Hydrogels are widely used in flexible sensing, drug delivery, and tissue engineering due to their outstanding flexibility and biocompatibility, etc. However, the development of conductive hydrogels with high strength, toughness, and fatigue resistance still exists significant challenges. This study introduced a novel toughening strategy based on the "pinning effect", utilizing submicron carbon cluster (CCs) with a unique π-conjugated core prepared with self-assembly and acrylamide to fabricate high strength and toughness hydrogels. The resulting CCs, coupled with stress dissipation, chain entanglement, and interfacial interactions with polyacrylamide (PAM), effectively arrested crack propagation during stretching, thereby enhancing mechanical performance. The mechanical properties of the PAM-CCs hydrogels are significantly improved compared to PAM hydrogel, showing a fracture strength of 2.33 MPa (2850% increase), an elongation of ≈2400% (700% increase), a fracture energy of 126.4 kJ m-2 (3461% increase), and toughness of 14.94 MJ m-3 (10571% increase). Besides, PAM-CCs hydrogel also revealed good adhesion, compression, and conductivity properties. This strategy do not require complex design or processing, using a simple and fast approach that showed immense potential for applications of hydrogels requiring high mechanical performance.