Nano-Blocks That Mix And Unmix In Response To Heat

Researchers in Japan have designed two types of nano-blocks that can combine and scramble repeatedly based on temperature differences in their environment.

AsianScientist (Apr. 11, 2019) – Researchers in Japan have designed two types of nano-sized building blocks that can automatically connect into cubes and scramble back into individual components based on the temperature of their environment. They published their findings in Nature Communications.

When two liquids—such as ink and water—are added together, they automatically disperse until they are perfectly mixed. However, separating the ink from the water is difficult.

Seeking to create a substance capable of reversible mixing, researchers led by Professor Shuichi Hiraoka at the University of Tokyo, Japan, developed two types nano-blocks that can connect or scramble themselves based on temperature differences.

The two types of nano-blocks are nearly identical and shaped like snowflakes, but differ in their color—red and blue. A cube assembled from red blocks is stable below 130 degrees Celsius, while a cube assembled from blue blocks is stable only below 65 degrees Celsius. When kept apart, the nano-blocks connect into entirely red or entirely blue uniform cubes.

When the two types of cubes are mixed together at room temperature, the red and blue building blocks automatically recombine into the most stable type of cubes, which are made of any combination of three red and three blue blocks. This mixture of red-blue cubes is analogous to well-mixed ink and water.

To obtain entirely red and entirely blue cubes once more, the researchers first heated the mixture to 100 degrees Celsius, which causes the blue cubes to become unstable and float off as individual molecules, while the red building blocks recombine into entirely red cubes.

Thereafter, the researchers rapidly cooled the mixture to zero degrees Celsius so that the red cubes stay together while the blue building blocks automatically assemble into entirely blue cubes. The team also showed that the two types of nano-blocks can be kept separate in the same container by adding molecules like hydocarbons.

“In the future, we plan to develop an even more complicated chemical system based on molecular cubes, using the unique self-assembly ability and a variety of energy sources beyond just heat,” said Hiraoka.

The article can be found at: Zhan et al. (2019) Temperature-controlled Repeatable Scrambling and Induced-sorting of Building Blocks Between Cubic Assemblies.


Source: University of Tokyo; Photo: Pixabay.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Asian Scientist Magazine is an award-winning science and technology magazine that highlights R&D news stories from Asia to a global audience. The magazine is published by Singapore-headquartered Wildtype Media Group.

Related Stories from Asian Scientist