Tough Hydrogels with Robust Wet Adhesion via Entropy-Driven Hydrogen Bond Reorganization

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Hydrogels for tissue repair require both mechanical strength and strong interfacial adhesion.
• Conventional strategies using hydrogen bonding face a trade-off between bulk strength and wet adhesion due to limited chain mobility.
• Optimizing hydrogel performance necessitates overcoming the inherent limitations of hydrogen bond distribution.

Purpose of the Study:

• To develop an entropy-driven strategy for hydrogels that decouples hydrogen bond distribution.
• To simultaneously achieve high bulk mechanical strength and robust wet adhesion in hydrogels.
• To overcome the strength-adhesion trade-off in conventional hydrogel strengthening methods.

Main Methods:

• Utilized an entropy-driven approach starting from a high-entropy mixture.
• Engineered hydrogen bond concentration in the bulk via entropy-favored reconfiguration.
• Induced localized phase separation to create a hydrogen bond-depleted interfacial layer.
• Facilitated dynamic polymer-tissue hydrogen bonding at the interface.

Main Results:

• Achieved a high modulus hydrogel (∼13 MPa) with robust wet adhesion.
• Demonstrated sealing capabilities beyond physiological limits (up to 368 mmHg).
• Successfully repaired models of skin injury, oral mucosal ulceration, and cardiac bleeding.

Conclusions:

• The entropy-driven strategy effectively decouples hydrogen bonds, enhancing both bulk strength and wet adhesion.
• The developed hydrogel exhibits excellent mechanical properties and interfacial bonding for demanding tissue repair applications.
• This approach offers a promising new direction for designing high-performance biomaterials for regenerative medicine.