Aligned Lubricated Short Nanofibers Enable Cartilage‐Mimetic Hydrogels with Mechanical Toughening, Piezoelectric Amplification, and Anisotropic Friction

Abstract

Bioinspired hydrogels are promising candidates for the development of multifunctional soft materials, yet the integration of anisotropic friction control, mechanical robustness, and piezoelectricity within a single material remains challenging. Here, a biomimetic hydrogel was successfully developed by incorporating lubricated piezoelectric short nanofibers, which were aligned through stretching and subsequently stabilized by ionic crosslinking to construct an anisotropic architecture. Benefiting from this design, the hydrogel simultaneously achieved high mechanical performance (strength about 42.9 MPa, toughness about 38.9 MJ·m −3 ). It also exhibited pronounced frictional anisotropy with the direction‐dependent lubrication behavior, where the friction coefficient was reduced to about 0.0087–0.0261 after incorporation of the multifunctional nanofibers, and maintained an ultralow friction coefficient (about 0.0097) throughout a continuous friction test for 3 h. Additionally, the fiber alignment enhanced the piezoelectric output by 2.3‐fold, increasing the voltage signal from about 256 mV in the unstretched state to about 600 mV under the same external excitation. Overall, this work established a simple yet effective strategy for engineering multifunctional hydrogels with coupled mechanical, anisotropic frictional, and electromechanical properties, broadening the design paradigm of bioinspired soft materials.