Reference News Network reported on February 23 that the website of popular science recently reported that scientists have created plastic comparable to steel - it is as strong as steel, but not as heavy as steel.
Plastics are sometimes called "polymers" by chemists. They have long-chain molecules made up of short repeating units called "monomers". Unlike previous polymers with the same strength, this new material appears entirely in the form of membrane. Its sealing property is also 50 times that of the most airtight plastic on the market. Another noteworthy aspect of this polymer is that its synthesis is very simple. It only needs cheap materials to be manufactured in indoor environment. The polymer can be processed into large sheets only a few nanometers thick. The researchers published their findings in the journal Nature on February 2.
This material is called "polyamide". It is a threaded network of amide molecular units (amides are chemical groups of nitrogen attached to carbon atoms combined with oxygen). Such polymers include Kevlar synthetic fiber and refractory fabric Nomex, which are used to make bulletproof vests. Like Kevlar, the polyamide molecules in this new material will be connected to each other through their long-chain hydrogen bonds, so as to enhance the overall strength of the material.
"They stick together like velcros," said Michael strano, a chemical engineer at the Massachusetts Institute of technology and lead author of the study Tearing this material requires not only cutting off a single molecular chain, but also overcoming intermolecular hydrogen bonds throughout the polymer beam.
In addition, the new polymer can automatically form thin sheets. This makes the material easy to process. It can be made into a film or used as a film like surface coating. Traditional polymers often expand in the form of linear chains, or expand and connect repeatedly in three dimensions without selection. But strano's polymer expands in a unique two-dimensional form to form nano flakes.
"Can you polymerize in flakes? It turns out that you can't usually do it before we do it. So we found a new mechanism," strano said In this recent work, his team has overcome various obstacles to make this two-dimensional polymerization possible.
In a world surrounded by plastics, society has reason to be excited about a new type of polymer whose mechanical properties are by no means ordinary, strano said. This aromatic polyamide is very durable, which means that we can use a small amount of stronger materials to make common plastic products such as coatings, bags and food packaging. Strano added that from a sustainability perspective, this super strong two-dimensional polymer represents a step in the right direction to keep the world away from plastics.
