Robust, self-healing hydrogels synthesised from catechol rich polymers.

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials Engineering

Background:

• Coordinative interactions between polymer-bound catechols and metal ions are crucial for bio-inspired soft materials.
• Developing efficient methods to create catechol-rich polymers is essential for advancing this field.

Purpose of the Study:

• To demonstrate a rapid reductive amination (RA) strategy for synthesizing catechol-rich polymers.
• To investigate the properties of hydrogels formed from these catechol-rich polymers using transition metal ions.

Main Methods:

• Utilized reductive amination (RA) to graft varying amounts of catechol pendants onto chitosan in an aqueous medium.
• Investigated gelation of catechol-grafted chitosan in the presence of transition metal ions (Fe(iii)) or chemical oxidants (NaIO4).
• Characterized the resulting hydrogels using UV-vis and Raman spectroscopy, and evaluated their mechanical and self-healing properties.

Main Results:

• Achieved controlled grafting of catechol units onto chitosan (18-80 mol%) via RA under ambient conditions.
• Successfully formed hydrogels capable of gelating water, even in acidic conditions, with lower crosslinker concentrations correlating with higher catechol content.
• Obtained highly ductile and self-healing hydrogels with excellent load-bearing capabilities, outperforming those formed by oxidative crosslinking.

Conclusions:

• The RA strategy offers a facile and rapid route to catechol-rich polymers.
• The resulting catechol-rich polymers can form robust, self-healing hydrogels with tunable properties, suitable for advanced bio-inspired soft materials.