Mussels Inspire the Making of Self-Repairing Surfboards

Imagine owning a surfboard that can seal its own cracks without having to cure in the sun for days. That's a reality that may be made possible thanks to a new synthesized polymer inspired by the sticky properties of mussels.

Researchers from the University of California Santa Barbara (UCSB) were interested in self-healing capabilities in moist or underwater conditions because it is a polymer field that hasn't gotten a lot of attention.

According to UCSB's Kolbe Ahn, dry condition self-healing polymers have been researched since the 1990s, but there is also a great demand for underwater self-healing polymers that is being left unmet.

"Much of the time, the presence of water limits the ability of an adhesive to stay tacky," Ahn's colleague, Herbert Waite, said in a statement. "So even polymers that can self-heal under dry conditions are frustrated from doing so underwater."

According to a study published in the journal Nature Materials, what stops traditional adhesives from holding cracks and breaks together is a thin layer of superficial liquid. This layer may be partially penetrated by a dry adhesive with some force, but the layer prevents the adhesive from directly applying to an entire surface area.

Imagine trying to push two puzzle pieces together with one hand. You could probably do it if you had the use of all your fingers, but suddenly someone sticks a bottle of water in the same hand. Now you have the use of only a few or your fingers and the task becomes much harder.

Mussels, however, have been seen to keep a firm grip on even the wettest of surfaces, showing that they somehow ignore this liquid layer - dropping the bottle, if you will. The secret is the secretion of a rare protein.

"In that particular protein, the percentage of catechol groups is high: up to a third of all residues," Waite explained.

Catechol, an organic compound, is not commonly found in proteins, hinting that it was what was allowing underwater adhesion.

The study found that polymer crafted from a synthetic version of the catechol protein was very effective at repairing and adhering to itself even under water.

The researchers suggest that an object coated or even entirely made of this polymer could quickly seal stress lines and cracks, leading to a very sturdy surfboard perfect for catching waves.