Scientists discover material that can be made like plastic but behaves like metal

Scientists at the University of Chicago have discovered a way to create a material that can be made like a plastic, but conducts electricity more like a metal.

The research, published October 26 in Nature, shows how to make a kind of material in which the molecular fragments are mixed and disordered, but which can still conduct electricity very well.

It’s against all the rules we know about conductivity – to a scientist it’s a bit like seeing a car go through water and go 110 km/h. But the discovery could also be extraordinarily useful; if you want to invent something revolutionary, the process often begins with the discovery of a completely new material.

“In principle, this paves the way for the design of an entirely new class of electrically conductive materials that are easy to shape and very robust in everyday conditions,” said John Anderson, associate professor of chemistry at the University of Chicago and the lead author of the study. “Essentially, this suggests new possibilities for an extremely important technology group of materials,” said Jiaze Xie (Ph.D. ’22, now at Princeton), the paper’s first author.

“There is no solid theory to explain this”

Conductive materials are absolutely essential if you’re making any type of electronic device, whether it’s an iPhone, solar panel, or TV. By far the oldest and most important group of conductors is that of metals: copper, gold, aluminum. Then, about 50 years ago, scientists were able to create conductors made from organic materials, using a chemical treatment called “doping”, which sprinkles different atoms or electrons through the material.

This is advantageous because these materials are more flexible and easier to process than traditional metals, but the problem is that they are not very stable; they can lose conductivity if exposed to moisture or if the temperature gets too high.

But basically, these two organic and traditional metal conductors share a common feature. They are made up of straight, tight rows of atoms or molecules. This means that electrons can easily flow through the material, much like cars on a highway. In fact, scientists thought that a material had to have these straight and orderly rows in order to efficiently conduct electricity.

Then Xie started experimenting with some materials discovered years ago but largely ignored. He strung nickel atoms like beads into a string of molecular beads made of carbon and sulfur, and began testing.

To the amazement of scientists, the material easily and strongly conducts electricity. Moreover, it was very stable. “We heated it, cooled it, exposed it to air and moisture, and even poured acid and base over it, and nothing happened,” Xie said. This is extremely useful for a device that needs to work in the real world.

But for the scientists, what was most striking was that the molecular structure of the material was messy. “From a fundamental perspective, it shouldn’t be able to be a metal,” Anderson said. “There is no solid theory to explain this.”

Xie, Anderson and their lab worked with other scientists at the university to try to figure out how the material can conduct electricity. After tests, simulations and theoretical work, they believe that the material forms layers, like leaves in a lasagna. Even though the sheets spin sideways, no longer forming a neat lasagna stack, the electrons can still move horizontally or vertically, as long as the pieces are touching.

The end result is unprecedented for a conductive material. “It’s almost like conductive Play-Doh – you can put it in place and it conducts electricity,” Anderson said.

Scientists are thrilled because the discovery suggests a fundamentally new design principle for electronics technology. Drivers are so important that virtually any new development opens up new avenues for technology, they explained.

One of the interesting features of this material is the new processing options. For example, metals usually need to be melted down in order to be shaped into the right shape for a chip or device, which limits what you can do with them, as other components of the device need to be able to withstand it. to the heat necessary for the treatment. these materials.

The new material has no such restriction because it can be made at room temperature. It can also be used where the need for a device or device parts to withstand heat, acid or alkalinity, or moisture has previously limited engineers’ options for developing new technology. .

The team is also exploring the different forms and functions the material could have. “We think we can make it 2D or 3D, make it porous, or even introduce other functions by adding different linkers or nodes,” Xie said.