Researchers at the Technical University Munich developed supramolecular materials, which molecules disintegrate at a predetermined time.

Most artificial substances, from plastic bottles to T-shirts, are chemically very stable. To decompose them back into their components, a lot of energy has to be used.

In nature, on the other hand, biological cells are constantly synthesising new molecules from recycled ones. Some of them assemble into larger structures, which are called supramolecular assemblies. These assemblies form the structural components of the cell.

Artificial materials do not exchange molecules and energy, remaining the way they are, while living, biological materials, like skin and cells, need a constant input of energy and building blocks for their construction and maintenance. As long as enough energy is available, damaged components and entire cells can be broken down and replaced. If no energy is available, the organism dies and disintegrates into its basic building blocks.

The researchers in Munich based their materials on the natural model. The molecular building blocks are initially freely mobile, but when energy is added in the form of high-energy molecules, supramolecular structures form.

Once the energy disappears, the structures disintegrate. Therefore, the lifetime of the material can be predefined by the amount of energy is added. In turn, the degraded material can be reused by simply adding another batch of high-energy molecules.

The structures could be used for completely disappearing ink, or biomedical uses. On the long term, it might even be possible to develop supramolecular machines or mobile phones.

Photo: Benedikt Rieß / TUM