Fatigue-resistant adhesion of hydrogels

Area of Science:

• Biomaterials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Soft connective tissues exhibit remarkable fatigue-resistant adhesion to bone, maintaining toughness over millions of loading cycles.
• Achieving similar fatigue-resistant adhesion in synthetic hydrogels bonded to engineering materials remains a significant challenge.
• This capability is crucial for applications like artificial cartilages, tendons, antifouling coatings, and hydrogel robots.

Purpose of the Study:

• To develop a method for creating fatigue-resistant adhesion between synthetic hydrogels and engineering materials.
• To mimic the nanostructured interfaces found in natural connective tissues for enhanced material properties.
• To enable robust hydrogel coatings on diverse materials and complex geometries.

Main Methods:

• Inspired by natural tissue interfaces, ordered nanocrystalline domains of synthetic hydrogels were bonded to engineering materials.
• The interfacial fatigue threshold was measured to quantify adhesion strength and resistance to crack propagation.
• The friction and wear properties of the hydrogel coatings against natural cartilages were evaluated.

Main Results:

• The developed method achieved a fatigue-resistant adhesion with an interfacial fatigue threshold of 800 J m^-2.
• Fracture analysis indicated that ordered nanostructures require higher energy to break than amorphous polymer chains, contributing to fatigue resistance.
• The hydrogel coatings demonstrated low friction and low wear when interacting with natural cartilages.

Conclusions:

• Bonding ordered nanocrystalline hydrogel domains creates highly fatigue-resistant adhesion on engineering materials.
• This biomimetic approach overcomes limitations in synthetic hydrogel adhesion, enabling advanced applications.
• The resulting hydrogel coatings offer promising performance for artificial tissues and low-friction interfaces.