MIT scientists create two-dimensional polymers as strong as steel

Science does not respect timetables. Sometimes it takes years or even decades of experimentation, dead ends and failures before a breakthrough occurs. MIT scientists have been trying for two decades to make a two-dimensional polymer, something that all of their theories and models suggested was possible but could never be created in the lab. The scientists had convinced themselves that it was impossible to induce polymers to form 2D sheets.

According to an MIT blog post, chemical engineers at MIT have created a new material using a new polymerization process that is stronger than steel and as light as plastic. The best part is that it can be easily made in large quantities. Prior to this breakthrough, all polymers formed one-dimensional spaghetti-like chains. The new material is a two-dimensional polymer that self-assembles into sheets.

It could be used as a lightweight, durable coating for car parts or cell phones, or as a building material for bridges or other structures, says Michael Strano, a professor of chemical engineering at MIT and lead author of the new study. of research. “We don’t usually think of plastics as something you could use to support a building, but with this material you can enable new things,” he says. “It has very unusual properties and we are very excited about it.”

Polymers and monomers

Polymers, which include all plastics, are made up of chains of building blocks called monomers. These chains grow by adding new molecules to their ends. Once formed, the polymers can be shaped into three-dimensional objects, such as water bottles, using injection molding techniques.

Polymer scientists have long hypothesized that if polymers could be made to expand into a two-dimensional sheet, they should form extremely strong and lightweight materials. However, many decades of work in this area have led to the conclusion that it is impossible to create such sheets. One reason for this is that if a single monomer rotates up or down out of the plane of the growing sheet, the material will begin to expand three-dimensionally and the sheet-like structure will be lost.

However, in the new study, Strano and his colleagues proposed a new polymerization process that allows them to generate a two-dimensional sheet called polyaramid. For monomeric building blocks, they use a compound called melamine, which contains a ring of carbon and nitrogen atoms. Under the right conditions, these monomers can grow in two dimensions, forming discs. These disks stack on top of each other, held together by hydrogen bonds between the layers, making the structure very stable and strong.

I may have failed organic chemistry in college, but I know that hydrogen bonds are some of the strongest in the world of chemistry. This is one of the reasons why it takes so much energy to separate the hydrogen and oxygen atoms in a water molecule.

“Instead of creating a spaghetti-shaped molecule, we can create a sheet-like molecular plane, where we get the molecules to hook together in two dimensions,” Strano explains. “This mechanism occurs spontaneously in solution, and after synthesizing the material, we can easily spin coat extraordinarily strong thin films.”

Because the material self-assembles in solution, it can be made in large quantities by simply increasing the amount of raw materials. The researchers showed they could coat surfaces with films of the material, which they call 2DPA-1. “With this breakthrough, we have planar molecules that will be much easier to shape into a very strong but extremely thin material,” Strano says.

Light but strong

The researchers found that 2DPA-1 has a modulus of elasticity – a measure of the force needed to deform a material – that is between 4 and 6 times greater than bulletproof glass. They also found that its yield strength – a measure of the force needed to break a material – is twice that of steel. Yet it only has about one-sixth the density of steel.

Matthew Tirrell, dean of the Pritzker School of Molecular Engineering at the University of Chicago, who was not involved in the research, explains that the new technique “embodies very creative chemistry for making these linked 2D polymers. An important aspect of these new polymers is that they are easily solution processable, which will facilitate many new applications where a high strength-to-weight ratio is important, such as new composite materials or diffusion barriers.

Impermeable to gases and liquids

Another key feature of 2DPA-1 is that it is impermeable to gases and liquids. While other polymers are made from coiled chains with gaps that allow gases and liquids to seep through, the new material is made from monomers that interlock like LEGOs, meaning the molecules gas and liquid cannot pass between them. “This could allow us to create ultra-thin coatings that can completely block water or gases from passing through,” Strano says. “This type of barrier coating could be used to protect metal in cars and other vehicles, or steel structures.”

Strano and his students are now studying in more detail how this particular polymer is able to form 2D sheets, and they are experimenting with altering its molecular composition to create other types of new materials.

The research was funded by the Center for Enhanced Nanofluidic Transport, an Energy Frontier Research Center sponsored by the US Department of Energy Office of Science and the Army Research Laboratory. There is a lesson to be learned from this. This type of research requires significant funding – more than private enterprise could ever justify. At a time when everything governments do is branded by some as a waste of money and an affront to individual liberty, perhaps now is the time to give credit where credit is due, despite Tucker Carlson and his anti-democracy brigand brigade.

Takeaway meals

You never know where things created in labs can lead. The glue on the sticky notes is the result of a failed experiment to make advanced adhesives capable of bonding airplane wings to fuselage. Could a super-tough impermeable coating make transporting hydrogen economically feasible? Could it end salt corrosion on highway bridges or reduce the weight of cars and trucks so they use energy more efficiently?

If you like getting into the stock market, this is the kind of idea that could create significant wealth for patient investors who are able to take a long-term approach. It’s actually quite exciting, when you think about it. So many possibilities and thousands more that no one has thought of yet. Hang on to your hats. It could be bigger than Tang!

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