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

Abstract

Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing1 followed by fluid–fluid phase separation, such as coacervation2–5. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water–DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (~25 s) and robust underwater contact adhesion (Wad ≥ 2 J m−2) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials.

Mussel adhesion – essential footwork

“…Phase inversions are common in the manufacture of polymeric membranes and typically are driven by changes in interfacial energy, viscosity and surface area between the phases (Strathmann and Kock, 1977). A recent investigation of a synthetic coacervate model system inspired by mussel adhesion revealed that complex coacervates can undergo phase inversion to form a structured fluid; the continuous inverted fluid phase then hardens to form a load-bearing porous material (Zhao et al, 2016). The relevance of these results to plaque formation remains to be demonstrated with plaque proteins.…”

Recent Progress of Mussel‐Inspired Underwater Adhesives

“…[29] A catechol-functionalized weak polyanion (poly-(acrylic acid)) was premixed with a polycation(bis-(trifluoromethane-sulphonyl)imide (Tf 2 N)) in dimethyl sulphoxide (DMSO). [30] Based on the influence of dielectric constants (ɛ) to ionization in weak polyelectrolytes, [31] the solvent exchange between DMSO and water can realize the robust underwater adhesion (W ad ≥2 J•m 2 ) with the electrostatic complexation, phase inversion, and rapid setting (~25 s). [30] The complexed underwater adhesive is applied to various substrates, such as plastics, glasses, metals, biological materials.…”

“…[30] Based on the influence of dielectric constants (ɛ) to ionization in weak polyelectrolytes, [31] the solvent exchange between DMSO and water can realize the robust underwater adhesion (W ad ≥2 J•m 2 ) with the electrostatic complexation, phase inversion, and rapid setting (~25 s). [30] The complexed underwater adhesive is applied to various substrates, such as plastics, glasses, metals, biological materials. [30] These biomimetic approaches may accelerate the development of the adhesives for industrial or biomedical applications.…”

“…[30] The complexed underwater adhesive is applied to various substrates, such as plastics, glasses, metals, biological materials. [30] These biomimetic approaches may accelerate the development of the adhesives for industrial or biomedical applications.…”

Bioinspired Superdurable Pestle‐Loop Mechanical Interlocker with Tunable Peeling Force, Strong Shear Adhesion, and Low Noise

“…Gecko foot encourages another kind of amazing bioinspired study from the viewpoint of surface adhesion,6 together with other natural adhesive systems like plant,7 insect,8 tree frog,9 octopus,10 and mussel 11. The most popular mechanical interlocker, velcro12 (hook‐loop interlocker) inspired by the hooks of burdock, has been applied in many fields since it was invented, such as clothing, room apparatus, and medical bandages.…”