Freeze-Casting Anisotropic Hydrogels with Multi-Dynamic Bonding for Enhancing Fatigue Resistance and Environmental...

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Hydrogels are crucial for wearable devices, soft robots, and human-machine interfaces due to their mechanical properties and biocompatibility.
• Conventional hydrogels face limitations in mechanical strength, fatigue resistance, and environmental adaptability, hindering long-term use in extreme conditions.

Purpose of the Study:

• To develop high-strength, fatigue-resistant, and environmentally adaptive hydrogels for demanding engineering applications.
• To overcome the limitations of conventional hydrogels through innovative material design and fabrication.

Main Methods:

• A synergistic strategy combining freeze-casting with multi-dynamic hydrogen bonding networks was employed.
• Directional freezing created aligned anisotropic microstructures, while cellulose nanofibers (CNFs) and tannic acid (TA) formed multi-scale hydrogen-bond networks within a polyvinyl alcohol (PVA) matrix.

Main Results:

• The fabricated PVA-based hydrogels exhibited high tensile strength (15.26 MPa) and elastic modulus (15.84 MPa).
• Exceptional fatigue resistance was demonstrated, with threshold tearing energy of 0.1233 kJ/m² and critical tearing energy of 1935.14 kJ/m².
• Hydrogels retained over 100% of their mechanical properties and structural integrity after 14 days in a high-pressure saline environment (20 MPa, 35‰ salinity), showing excellent environmental stability.

Conclusions:

• The developed PVA-based hydrogels demonstrate superior mechanical properties, fatigue resistance, and environmental adaptability.
• This innovative fabrication strategy provides a groundbreaking solution for hydrogel applications under extreme conditions.
• The findings pave new avenues for expanding engineering applications of hydrogels in demanding scenarios.