Lower Critical Solution Temperature-Driven Self-Coacervation of Nonionic Polyester Underwater Adhesives

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Adhesion Science

Background:

• Aquatic organisms like mussels use coacervation for underwater adhesion, delivering protein-rich adhesives.
• Mussel adhesive protein Mfp-3s utilizes coacervation, but synthetic mimics using oppositely charged polymers have limited pH and salt stability.
• Existing synthetic coacervate adhesives are sensitive to environmental conditions, restricting their practical applications.

Purpose of the Study:

• To design and synthesize novel nonionic, self-coacervating polyesters inspired by mussel foot protein Mfp-3s.
• To overcome the limitations of existing coacervate adhesives by enhancing stability across a wide range of pH and ionic strength.
• To develop bioabsorbable, photo-cross-linkable adhesives for underwater applications.

Main Methods:

• Utilized lower critical solution temperature-driven coacervation for material design.
• Synthesized tropoelastin-like, bioabsorbable, nonionic polyesters.
• Evaluated underwater adhesive properties, including coacervation behavior and adhesion speed.

Main Results:

• Developed nonionic, self-coacervating polyesters that mimic mussel adhesive protein Mfp-3s.
• These "charge-free" polyesters exhibit coacervation in wide pH (3-12) and ionic strength (0-1 M NaCl) ranges.
• Rapid underwater adhesion (<300 s) to submerged substrates was achieved.

Conclusions:

• Introduced smart materials that replicate the self-coacervation and environmental stability of Mfp-3s.
• Demonstrated the potential of these nonionic polyesters as robust underwater adhesives.
• Highlighted applicability in biological adhesive scenarios with expected high water content, salts, and pH fluctuations.