Fabricating ultra-robust hydrogels with adhesive properties by restraining crack propagation with bamboo cellulose-based carbon nanomaterials

The bamboo fiber functionalized with phthalic anhydride underwent carbonization, yielding bamboo cellulose-derived carbon nanomaterials (C-BCN). These C-BCN were subsequently integrated into an acrylamide precursor solution to synthesize an ultra-robust, fatigue-resistant conductive hydrogel (PAM-C-BCN). During in situ polymerization, the abundant active sites on the C-BCN surface facilitated covalent cross-linking with the polyacrylamide (PAM) matrix. This interfacial interaction promoted strong adhesion between the PAM chains and the carbon nanostructures, forming a densely interpenetrated network through macromolecular entanglement. The synergistic coupling of the rigid C-BCN framework with the flexible polymer chains conferred exceptional mechanical resilience and energy dissipation capabilities to the composite hydrogel. Compared to the PAM hydrogel, the PAM-C-BCN hydrogel exhibited an improvement in mechanical properties, with a fracture strength of 363 kPa (a 2.5% increase), an elongation of approximately 2 254% (a 2.0% increase), a fracture energy of 30 kJ/m² (a 3.1% increase), and a toughness of 3.04 MJ/m³ (a 4.1% increase). Moreover, PAM-C-BCN hydrogel demonstrated high adhesion (up to 7.5 kPa on pigskin) and conductivity (0.21 S/m). This strategy required neither complex design nor processing, offering a simple and efficient approach with great potential for hydrogel applications requiring high mechanical performance. At the crack tip of PAM-C-BCN hydrogel, C-BCN exhibited superior crack propagation resistance compared to SiO₂ nanoparticles. Importantly, this strategy offered valuable insights for developing tough and stretchable hydrogels.