Strong, tough and anisotropic bioinspired hydrogels

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Soft materials like hydrogels are crucial for tissue engineering, soft robotics, and wearable electronics.
• Achieving high strength and toughness in hydrogels comparable to biological tissues remains a significant challenge.
• Existing methods often struggle to balance mechanical robustness with other desirable material properties.

Purpose of the Study:

• To develop a novel strategy for fabricating anisotropic polyvinyl alcohol (PVA) hydrogels with enhanced mechanical properties.
• To investigate the mechanisms behind the reinforcement and toughening of these hydrogels.
• To explore the potential applications of these advanced hydrogels in various fields.

Main Methods:

• A solvent-exchange-assisted wet-stretching strategy was employed to prepare anisotropic PVA hydrogels.
• Macromolecular chain movement and polymer network optimization were key parameters.
• Mechanisms of "macromolecule crystallization and nanofibril formation" were identified as the sources of reinforcement and toughening.

Main Results:

• The fabricated PVA hydrogels exhibited exceptional mechanical properties, including high fracture stress (12.8 MPa) and fracture strain (1719%).
• The hydrogels demonstrated superior work of fracture (134.47 MJ m⁻³) and fracture toughness (305.04 kJ m⁻²), surpassing many existing strong hydrogels and natural tendons.
• Additional properties like excellent conductivity, strain sensing, water retention, and biocompatibility were achieved.

Conclusions:

• The proposed solvent-exchange-assisted wet-stretching method effectively produces multifunctional anisotropic hydrogels with tunable high strength and toughness.
• The findings provide a new pathway for creating biomimetic materials with properties comparable to natural tissues.
• These advanced hydrogels hold significant promise for applications in regenerative medicine, flexible sensors, and soft robotics.