Researchers from China have developed a powerful new adhesive that grips strongly in extreme temperatures, from the deep freeze of liquid nitrogen to the sweltering heat of an oven. Better yet, it can be broken back down into its component parts and reused without losing strength.
The new adhesive belongs to a class known as supramolecular adhesives, which are made up of molecular components specially designed to self-assemble into strong bonds during curing. One is a ring-shaped molecule called a crown ether, which can wrap around the second component, a small protein produced by bacteria.
When these are combined and the mixture is heated, the crown sticks to the surface of the protein tightly, strengthening the bond through several molecular interactions, including their opposite charges. The team described it as “welding” the molecules together, giving them an incredibly strong interlocking structure.
That makes for an incredibly powerful adhesive. The team tested it out by gluing steel plates together, and found that they could withstand up to 22 Megapascals of shearing force. Most impressively, that strength worked not only at room temperature but anywhere from -196 °C (-320.8 °F) up to 200 °C (392 °F). It proved promising on other materials as well, and even worked underwater.
The team attributes the adhesive’s success in part to those strong supramolecular interactions. The tight bond drives water out of the protein, which means that when the temperature drops no ice crystals can form and crack open the material, as often happens with other glues. This could also help explain why it works underwater.
As an added bonus, those interlocking components can be dismantled on demand and recycled, with the second generation adhesive showing basically the same strength.
The researchers say that this supramolecular adhesive could be particularly useful for things that will face large temperature fluctuations during use, such as spacecraft.
The research was published in the journal Angewandte Chemie.
Source: Wiley
