Earthworm inspired lubricant self-pumping hydrogel with sustained lubricity at high loading

Area of Science:

• Materials Science
• Tribology
• Biomimetics

Background:

• Developing mechanically robust super-lubrication hydrogels with sustained lubricity at high pressures is a significant challenge.
• Existing hydrogels often lack durability and long-term performance under demanding conditions.

Purpose of the Study:

• To engineer a novel multilevel structural super-lubrication hydrogel (MS-SLH) system inspired by the earthworm epidermis.
• To achieve sustained lubrication and mechanical robustness in hydrogel materials for high-pressure applications.

Main Methods:

• Chemically dissociating a double network hydrogel to create a robust, wrinkled lubrication layer.
• Utilizing laser etching to form cylindrical texture pores, acting as lubricant-storing pockets.
• Investigating the hydrogel's surface properties, including ultrafast hydration and reversible pore behavior.

Main Results:

• The MS-SLH system demonstrated a very low coefficient of friction (COF) of ~0.0079 at high contact pressure (11.32 MPa).
• Achieved a stable super-lubrication lifespan with a COF of ~0.0028 at 8.48 MPa over 100,000 cycles without wear.
• Exhibited sustained lubricity for 3700 cycles with a limited lubricant volume (5 μL) in air.

Conclusions:

• The MS-SLH system's performance is attributed to electrostatic repulsion, a robust yet compliant lubrication layer, and self-pumping lubricant release.
• This biomimetic approach offers a scalable strategy for producing high-performance water-lubrication coatings.
• The developed hydrogel shows promise for applications in high-end medical devices and industrial moving parts requiring durable lubrication.