Chitosan/poly-γ-glutamic acid crosslinked hydrogels: Characterization and application as bio-glues

Area of Science:

• Materials Science
• Biotechnology
• Polymer Chemistry

Background:

• Developing sustainable and ecofriendly materials is crucial for reducing environmental impact.
• Chitosan and poly-γ-glutamic acid are biocompatible polymers with potential adhesive properties.
• Conventional adhesives often pose environmental and health concerns.

Purpose of the Study:

• To synthesize and characterize novel ecofriendly hydrogels using chitosan and poly-γ-glutamic acid.
• To evaluate the adhesive performance of these hydrogels on wood and aluminum substrates.
• To explore potential applications of these bio-adhesives in various industries.

Main Methods:

• Hydrogels were prepared by physically blending chitosan (CH) with two fractions of microbial poly-γ-glutamic acid (γ-PGA) at different mass ratios.
• Physicochemical, rheological, and morphological properties of the hydrogels were characterized.
• Lap shear tests were conducted to assess adhesive strength on wood and aluminum, comparing them to commercial vinyl and acetovinyl glues.

Main Results:

• Six physically crosslinked hydrogels were successfully synthesized.
• Hydrogels with the highest yield (CH/γ-PGA ratio of 3/7) demonstrated significant adhesive strength on wood and aluminum.
• Performance on wood was comparable to commercial glues, while CH/R2 showed superior performance on aluminum.
• Scanning electron microscopy confirmed strong physical bonding between hydrogels and substrates.

Conclusions:

• Ecofriendly hydrogels derived from chitosan and poly-γ-glutamic acid exhibit excellent bio-adhesive properties.
• These materials offer a sustainable alternative to conventional adhesives.
• Potential applications span diverse fields including paints, coatings, heritage preservation, and the medical sector.