Self-healing hydrogels could help seal leakages

San Diego, US- Bioengineers at the University of California, San Diego have developed a self-healing hydrogel that binds in seconds, as easily as Velcro, and is strong enough to withstand repeated stretching.

The material has a range of potential applications in areas such as medical sutures, self-healing plastics and industrial sealants. For instance, the gel may be used in the field of energy conservation where self-healing materials could reduce industrial and consumer waste.

Until now, researchers have been unable to develop hydrogels that can rapidly repair themselves when a cut is introduced, limiting their potential applications.

Researchers at UC San Diego have overcome this challenge using what they term as “dangling side chain” molecules. These molecules extend like fingers on a hand from the primary structure of the hydrogel network enabling them to grasp one another.

To design the chain molecules, the team performed computer simulations of the hydrogel network. The simulations revealed that the ability of the hydrogel to self-heal depended critically on the length of the side chain molecules.

When two cylindrical pieces of gels at the optimised length were placed together in an acidic solution, they stuck to each other instantly. Researchers further found that by adjusting the solution’s pH, they could weld and separate the pieces easily.

“Being bioengineers, one question that repeatedly appeared before us was if one could mimic self-healing in synthetic, tissue-like materials such as hydrogels. The benefits of creating such an aqueous self-healing material would be far-reaching in medicine and engineering,” said Shyni Varghese who led the project.

The rapidity of self-healing in response to acids makes the material a promising candidate to seal leakages from containers holding corrosive acids. To test this theory, Varghese’s lab cut a hole in the bottom of a plastic container, “healed” it by sealing the hole with the hydrogel and demonstrated that it prevented any leakage of acid through the hole.

Moving forward, UC San Diego hope to test the material on a larger scale. The team also hopes to engineer other varieties of hydrogels that self-heal at different pH values to extend the applications beyond those involving acidic conditions.