Whether in the ground, in water or in the air: glass remains stable for thousands of years. Alternatives made of plastics, on the other hand, break down into microplastics over time when they enter the environment. Neither is ideal from an environmental point of view. Now a biodegradable glass should minimize the ecological footprint of the material. A research team led by Xuehai Yan from the Chinese Academy of Sciences has presented how in the journal «Science Advances».
The experts use amino acids and short chains of these molecules, so-called peptides. They first heat these and then allow them to cool down quickly without creating a crystal structure.Instead, an amorphous structure – the essential characteristic of a glass is formed. The biggest hurdle that Yan’s team had to overcome was the heat stability of the starting molecules. Normally, these degenerate at the temperatures necessary for production. However, Yan and Co used chemical modifications to find a way to protect the molecules from this, for example by attaching acetyl or benzyloxycarbonyl groups.
The resulting glasses – so far probably only spheres of half a centimeter in diameter – were comparable in their properties and processing with conventional glass, writes the team. They would also be able to be processed by 3D printers. Tests have shown that small samples of this glass decompose into compost soil within about nine months. They serve the microorganisms as food and are thus recycled to a certain extent. The material also showed a fundamental suitability in animal experiments: it was degraded in the body of mice over time and could therefore be used for implants that dissolve on their own.
Source — https://www.spektrum.de/news/materialwissenschaft-ein-glas-das-biologisch-abbaubar-ist/2121969