Clay has been used in various kinds of pottery since prehistoric times, but in the 20th century plastic objects became much more ubiquitous. Now clay could see a widespread renaissance thanks to research by Takuzo Aida and colleagues at the University of Tokyo in Japan, which has brought a 21st century touch to this ancient material.
It turns out that water and clay (2–3% by mass) plus small amounts of suitable organic compounds (less than 0.4% by mass) can produce transparent hydrogels that could take the place of plastics. The materials produced in this way are mechanically strong, but what is more remarkable is that, if damaged, they will completely self-heal – after all, they are nearly all water. The key to these remarkable properties is the non-covalent supramolecular bonds between the dendritic organic molecules – ones that have many “fingers" to grab onto things – and the clay.
Unlike plastics, these hydrogels are environmentally friendly. Moreover, as the researchers point out, with the world’s focus on reducing dependency on fossil-fuel energy, there is a big role for materials that are much less dependent on petroleum than conventional plastics are.