Superstrong and Transparent Hydrogels with Homogeneous Multiple Networks

For the applications of synthetic hydrogels in wearable devices and underwater protection fields, both exceptional mechanical properties and high transparency are highly desired. Here, we produce a superstrong and transparent hydrogel with a homogeneous and densely interconnected polymer network. The obtained hydrogel has exceptional mechanical properties, for example, an ultimate strength of 44.2 ± 1.0 MPa and a toughness of 153.0 ± 3.6 MJ m^–3. The homogeneous triple-network structure endows the hydrogel with a high transparency of 90% and an excellent tensile strength of 35.5 ± 0.8 MPa in an underwater environment. The multiple effective energy dissipation mechanisms, including ion cross-linking, crystalline domains, and entanglements, synergistically enhance the mechanical properties. Moreover, such a superstrong and transparent hydrogel can be coated on the surface of underwater optical devices, playing the role of antifogging, antioiling, and wear resistance. Our strategy provides a new avenue to design functional hydrogel materials with excellent mechanical properties and high transparency.