Strain-Stiffening Hydrogels with Dynamic, Secondary Cross-Linking

Area of Science:

• Materials Science
• Biotechnology
• Polymer Chemistry

Background:

• Hydrogels are versatile water-swollen networks used in biomaterials and biotechnology.
• Responsive hydrogels that react to external stimuli like force are crucial for advanced applications.
• Incorporating force-responsiveness (mechanophores) into hydrogels remains an unproven challenge.

Purpose of the Study:

• To synthesize multifunctional polymers for creating force-responsive hydrogels.
• To investigate the creation of hydrogels with both permanent and dynamic cross-links.
• To achieve strain-stiffening behavior in hydrogels for biomaterial applications.

Main Methods:

• Synthesized multifunctional polymers containing zwitterions, alkenes, and disulfides.
• Fabricated hydrogels utilizing thiol-ene and disulfide cross-linking chemistries.
• Characterized hydrogel mechanical properties and response to applied strain using a constitutive model.

Main Results:

• Developed hydrogels exhibiting significant stiffening under compressive strain, increasing modulus by hundreds of kPa.
• Demonstrated successful integration of permanent (thiol-ene) and reversible (disulfide) cross-links.
• Identified optimal polymer compositions for maximizing force-responsive network behavior.

Conclusions:

• Successfully created strain-stiffening hydrogels with tunable mechanical properties.
• These novel hydrogels offer a platform for biomaterials requiring mechanoresponsive behavior.
• Potential applications include advanced tissue engineering and other fields needing dynamic material responses.