A high-strength self-healing nano-silica hydrogel with anisotropic differential conductivity

Soft nano electronic materials based on conductive hydrogels have attracted considerable attention due to their exceptional properties. Particle deposition and poor interface compatibility often diminish the mechanical strength and electron transport capabilities of the conductive hydrogel. Mechanical damage can severely impact the performance of the conductive hydrogel and can even damage electronic devices based on the conductive hydrogel. In the current study, a transparent nano-silica hydrogel is prepared by employing an extremely easy-to-operate method. This approach can preclude the deposition of particles via strong mechanical force. In addition, controlling the concentration of the reaction interface makes the hydrogel grow along the mechanical force in the direction with a special directional hole structure formed. The hydrogel is transparent, showing excellent self-healing properties—it can self-heal within 15 seconds. Remarkably, the hydrogel after self-healing maintains its performance. Moreover, it has excellent mechanical properties and can be stretched in length. Up to 1,200% of the original length, the tensile strength of the gel spline can reach 7 MPa. The viscosity of the hydrogel can reach 1.67 × 10⁸ (MPs). In addition, a large amount of Na⁺ in this hydrogel endow it a conductivity of 389 μs/cm. The conductivity of this hydrogel is adjustable result from the special pore structure. Lastly, the difference between the horizontal and vertical conductivity of the same sample can reach 3-4 times, thus this hydrogel can be used in the field of nano conductive materials.