Gels are commonly used products that are soft and sticky. They can be applied to hair or to the jelly-like components in various foodstuffs. While human skin shares gel-like characteristics, it has unique qualities that are very hard to replicate. It combines high stiffness with flexibility, and it has remarkable self-healing capabilities, often healing completely within 24 hours after injury.
Until now, artificial gels have either replicated this high stiffness or natural skin’s self-healing properties, but not both. Now, a team of researchers from Aalto University and the University of Bayreuth is the first to develop a hydrogel with a unique structure that overcomes earlier limitations, opening the door to applications such as drug delivery, wound healing, soft robotics sensors, and artificial skin.
In the breakthrough study, the researchers added exceptionally large and ultra-thin specific clay nanosheets to hydrogels, which are typically soft and squishy. The result is a highly ordered structure with densely entangled polymers between nanosheets, improving the hydrogel’s mechanical properties and allowing it to self-heal.
The secret of the material lies not only in the organised arrangement of the nanosheets, but also in the polymers that are entangled between them – and a process that’s as simple as baking. Postdoctoral researcher Chen Liang mixed a powder of monomers with water that contains nanosheets. The mixture was then placed under a UV lamp – similar to that used to set gel nail polish. ‘The UV-radiation from the lamp causes the individual molecules to bind together so that everything becomes an elastic solid – a gel,’ Liang explains.