Dually-dynamic covalent tetraPEG hydrogels end-linked with boronate ester and acylhydrazone groups

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Dynamic covalent chemistry enables the creation of adaptive materials.
• Poly(ethylene glycol) (PEG) stars are versatile building blocks for polymer networks.
• Self-healing and tunable properties are desirable for advanced materials.

Purpose of the Study:

• To synthesize well-defined dually dynamic hydrogels using PEG stars.
• To investigate the influence of dynamic covalent cross-links (boronates and acylhydrazones) on material properties.
• To explore the self-healing, mechanical, viscoelastic, and swelling/degradation behaviors of these hydrogels.

Main Methods:

• End-functionalization of four-armed poly(ethylene glycol) (tetraPEG) stars with glucoronate, acylhydrazide, and benzaldehyde groups.
• Cross-linking of functionalized tetraPEG stars using dynamic covalent chemistry, specifically boronates and acylhydrazones.
• Preparation and characterization of singly-dynamic, dually-dynamic, and double-like hydrogels at varying pH conditions (8.5, 10.5, 12.5).

Main Results:

• Successfully prepared dually dynamic hydrogels exhibiting robustness and self-healing capabilities.
• Demonstrated that the combination of boronate and acylhydrazone dynamic cross-links leads to enhanced material properties.
• Investigated hydrogel properties including mechanical strength, viscoelasticity, swelling, and degradation across different pH values.

Conclusions:

• The study provides a foundation for designing tunable polymeric dynamic covalent hydrogels.
• The developed hydrogels show promise for applications requiring self-healing and controlled stability.
• Precise control over dynamic cross-linking is key to tailoring hydrogel performance.