At MIT learned to control the properties of plastic

For over a hundred years of plastic products and plastics are widely used in many areas of our life. However, the physical properties of this material can depend not only on composition but also on the molecular structure. Recently, the engineers of the Massachusetts Technological University (MIT) have created a metal-organic polymer that can change shape when exposed to light waves of different lengths.

According to the editors of the journal Nature, the new material created by a team under the leadership of Yuveya GU. New metal-organic polymer cures under UV light and softens and becomes readily fusible under a green lamp. Change of physical properties occurs due to the change of the plastic particles. They consist of molecular chains of the ligands associated with the palladium atoms. Such compounds are called polymeric metal-organic due to the fact that the polymer have long “tails” that are going around the metal atoms, forming a geometric structure in the form of quadrangles.

The new material each palladium atom forms 4 chemical bonds with ligands. At the time when accumulated a lot of palladium and polymer molecules – in the structure of the formed clusters with a variable number of metal atoms. Scientists have found a way to create a “large” clusters, with 24 atoms of palladium to ligands 48 and “small” — 3 atom of palladium by 6 ligands. To control the transition between the clusters, the researchers added a substance DTE in the molecule of which the bond between the two sulfur atoms is formed and breaks under ultraviolet light. In ultraviolet radiation DTE molecule becomes more rigid and breaks small clusters, causing the palladium to form larger clusters. The reverse process occurs when under the influence of light the green bond in the molecule is destroyed DTE, which reduces the intensity of impact and creates small clusters.

It turned out that “small” clusters make the material very soft and fusible, which allows, for example, to repair mechanical damage. “Big” cause solidification. This is now possible to produce up to 7 cycles the state transition that does not affect the material properties, however this figure is projected to increase in the future. It is easy to guess that this type of plastic is perfect for creating things with extended life and recyclable.

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