Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomimetic Engineering

Background:

• Polyelectrolyte complexation is crucial for material formation but its evolution into solid microarchitectures is poorly understood.
• Existing methods for material formation often involve aqueous mixing and phase separation like coacervation.
• The sandcastle worm's cement proteins provide inspiration for novel adhesive strategies.

Purpose of the Study:

• To develop a versatile and strong underwater adhesive inspired by natural cement proteins.
• To investigate polyelectrolyte complexation triggered by solvent exchange for material formation.
• To achieve rapid setting and robust adhesion on various substrates under wet conditions.

Main Methods:

• Premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulfoxide (DMSO).
• Applying the pre-mixed solution underwater to diverse substrates.
• Utilizing water-DMSO solvent exchange to simultaneously actuate electrostatic complexation, phase inversion, and rapid setting.

Main Results:

• A microporous adhesive was formed through simultaneous complexation, inversion, and setting.
• Rapid underwater adhesion was achieved in approximately 25 seconds.
• Robust adhesion (Wad ≥ 2 J m⁻²) was demonstrated on plastics, glass, metals, and biological materials.

Conclusions:

• Solvent-exchange-triggered polyelectrolyte complexation offers a versatile route to strong, microporous adhesives.
• This biomimetic approach enables rapid and robust underwater adhesion on a wide range of surfaces.
• The developed adhesive has potential applications in wet environments where traditional adhesives fail.