Covalent Interfacial Anchoring of 1D-2D Hybrid Nanofillers to Poly(Vinyl Alcohol) Networks Enables High-Strength,...

Hydrogels with high strength, stiffness, and toughness under full hydration are essential for load-transfer applications such as artificial tendons, ligaments, and soft robotics. Yet achieving such performance remains difficult because conventional polymer networks are intrinsically soft and transfer stress inefficiently. Here, a covalent interfacial anchoring (CIA) strategy is introduced to enable high-strength, high-stiffness hydrogel microfibers under full hydration by chemically anchoring carbon nanotubes (CNTs) and graphene oxide (GO) within poly(vinyl alcohol) networks. In this network, CNTs contribute to axial load transfer, whereas GO forms glutaraldehyde-mediated PVA-GO acetal linkages that suppress nanofiller mobility during deformation and promote efficient stress transfer. The resulting hydrogel fibers achieve tensile strength of 132 MPa, modulus of 1.1 GPa and toughness of 25 MJ m^-3 under full hydration and maintain ∼88% displacement after 100 tendon-mimetic loading cycles. These findings highlight covalent interfacial anchoring as an effective strategy for engineering strong and stiff hydrogel fibers for tendon-like load-transfer applications.