Lubricate, Degrade, and Fertilize: A Multifunctional Superlubricating Hydrogel Inspired by Dolphin Skin

Engineering materials generally face challenges in simultaneously achieving high load-bearing capacity, superlubricity, and biodegradability. Additionally, they may impose an environmental burden upon disposal. Inspired by the microstructure of dolphin skin, this study developed a multifunctional superlubricating hydrogel composed of yam extract-PEGDA. It also proposed a dual-mechanism model in which micron-scale pore structures and hydration layer induced by hydrogen bonding synergistically contribute to the superlubricating performance. The hydrogel exhibits instantaneous superhydrophilicity, with a friction coefficient as low as 0.00191 under a contact pressure of 1.368 MPa. After 180 min of operation, the volumetric efficiency of the water hydraulic circular gear pump dropped to 58.3% with the uncoated bearing but remained at 82.7% with the hydrogel-coated bearing. After 30 days of soil incubation, the hydrogel showed ∼15.1% mass loss. Moreover, 14-day cultivation showed that soil with degraded hydrogel increased lettuce dry weight by ∼126.3% compared to the control group. This material combines the potential for sustained water-based lubrication with degradation-induced soil fertilization, providing a new strategy for developing green biomimetic lubricating materials.