Kevlar-inspired molecular nanofibers are stronger than steel

Self-assembly of molecules is widespread in nature, serving as a way of forming organized structures in

every living organism.This phenomenon can be seen, for example, when two strands of DNA - without any external push or direction - join together to form a double helix. Or, for example, when a large number of molecules combine to create membranes or other vital cellular structures.

The last couple of decades, scientists and engineersfollow nature's lead by creating molecules that self-assemble, for example in water. The goal is the creation of nanostructures, primarily in the biomedical field.

A team of scientists from MassachusettsInstitute of Technology (MIT) has developed a new class of small molecules that spontaneously assemble into nanoribbons with unprecedented strength while retaining their structure outside of water.

Usually self-assembly structures are modeled bya sample of the cell membrane. Their outer part is hydrophilic, while the inner part is hydrophobic. The configuration is based on radically different processes and provides the driving force for self-assembly. However, outside the water, such a structure disintegrates.

New design of a molecule created in MassachusettsInstitute of Technology, consists of three main components: the outer hydrophilic part, which "likes" to interact with water, the aramids in the middle for binding, and the inner hydrophobic part with its "aversion" to water. According to scientists, it is inspired by the structure of Kevlar. Aramids in the structure provide its chemical stability and strength.

Researchers have tested dozens of moleculesmeeting these criteria before finding a design that led to the creation of long ribbons with thickness on the nanometer scale. The authors then measured their strength and stiffness to understand the effect of incorporating Kevlar interactions between the molecules. They found that such nanofibers were unexpectedly strong - even stronger than steel.

This discovery made the authors wonder ifwhether to tie nanoribbons into a bundle to obtain stable macroscopic materials. The aligned fibers were pulled together into long strands that could be dried and processed. It turned out that they are capable of supporting 200 times their own weight.

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Aramid is a long chain of syntheticpolyamide, in which at least 85% of the amide bonds are attached directly to two aromatic rings. The properties of aramid fibers are determined by both chemical and physical microstructure.

Kevlar is a para-aramid fiber manufactured byby DuPont. Kevlar is highly durable. For the first time, Kevlar was obtained by the group of Stephanie Kwolek, an American chemist and employee of DuPont, in 1964, the production technology was developed in 1965, and industrial production began in the early 1970s.