MIT Scientists Create 2-Dimensional Polymers As Strong As Steel – CleanTechnica
Science does not respect timetables. Sometimes it takes years or even decades of experiments, blind alleys, and failures before a breakthrough occurs. Scientists at MIT have been trying for two decades to make a 2-dimensional polymer, something that all their theories and models suggested was possible but could never be actually created in the lab. Scientists had convinced themselves it was impossible to induce polymers to form 2D sheets.
According to an MIT blog post, MIT chemical engineers have created a new material using a novel polymerization process that is stronger than steel and as light as plastic. The best part is, it can be easily manufactured 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 itself 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 senior author of the new research study. “We don’t usually think of plastics as being something that 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’re very excited about that.”
Polymers & Monomers
Polymers, which include all plastics, consist of chains of building blocks called monomers. These chains grow by adding new molecules onto their ends. Once formed, 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 induced to grow into a 2-dimensional sheet, they should form extremely strong, lightweight materials. However, many decades of work in this field led to the conclusion that it was impossible to create such sheets. One reason for this was that if just one monomer rotates up or down out of the plane of the growing sheet, the material will begin expanding in three dimensions and the sheet-like structure will be lost.
However, in the new study, Strano and his colleagues came up with a new polymerization process that allows them to generate a 2-dimensional sheet called a polyaramide. For the monomer 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 disks. These disks stack on top of each other, held together by hydrogen bonds between the layers, which make the structure very stable and strong.
I may have been a failure at organic chemistry in college, but I know hydrogen bonds are some of the strongest in the world of chemistry. That’s one reason why it takes so much energy to break the hydrogen and oxygen atoms apart in a molecule of water.
“Instead of making a spaghetti-like molecule, we can make a sheet-like molecular plane, where we get molecules to hook themselves together in two dimensions,” Strano says. “This mechanism happens spontaneously in solution, and after we synthesize the material, we can easily spin-coat thin films that are extraordinarily strong.”
Because the material self-assembles in solution, it can be made in large quantities by simply increasing the quantity of the starting materials. The researchers showed that they could coat surfaces with films of the material, which they call 2DPA-1. “With this advance, we have planar molecules that are going to be much easier to fashion into a …….