ENGINEERING TECHNOLOGY

A team of Chinese scientists has created a new substance, elastic ceramics, plastics


Hardness and elasticity are a pair of “contradictory bodies” in nature, and it seems impossible to want a substance to have two properties at the same time.

Professor Tang Ruikang of the Department of Chemistry of Zhejiang University and researcher Liu Zhaoming collaborated to create a new substance that fuses organic compounds and inorganic ionic compounds at the molecular scale, perfectly achieving “compatibility” of hardness and elasticity in the same substance, while also having plasticity like plastics. The team named the new substance “elastomeric plastic.” The results were published online on June 8 in the journal Nature.

The results were highly praised by the reviewers and editors: “This paper reports a completely new material with the strength and hardness of ceramics and the deformability, flexibility and elasticity of polymers. This will be of interest not only to the materials science community, but also to the entire scientific community, because new materials always open up new possibilities. Nature also had a special research brief at the same time.

Group photo of the team. (Photo courtesy of the research group)

The “yellow buttons” are not easy to get

As can be seen at the scene, the new substance is a small yellow block like a button, which looks ordinary on the surface. Even the team didn’t realize it was a new substance at first.

Elastic ceramic plastic. (Photo courtesy of the research group)

Of course, such a new substance does not appear out of thin air, having previously undergone a rather long process of “gestation”.

In the traditional cognition, the preparation methods of materials in the field of inorganic chemistry and polymer chemistry are completely different, but in 2019, Tang Ruikang’s team proposed a new concept of “inorganic ion oligomers and their polymerization reactions”, breaking the boundaries between the two.

Since calcium carbonate can be prepared like plastics, can organic chemistry be used to make inorganic substances? The research group carried out a large number of experiments.

“Organic matter is linked by covalent bonds, inorganic ionic compounds are bound by ionic bonds, and this medium is very important to achieve the unity of organic matter and inorganic matter in one molecule.” Tang Ruikang said.

The research group integrates the synthesis concept of “functional group reaction” in organic chemistry into inorganic synthetic chemistry, designs a functional group reaction of inorganic ion oligomers, introduces organic functional molecules into “inorganic ion molecules”, and realizes the synthesis of hybrid molecules with organic fragments and inorganic ion fragments.

“After screening many chemical reactions, we finally chose the classic acid-base reaction in inorganic chemistry. This method can simply and quickly connect basic ionic salts with acidic organic molecules to form hybrid molecules. Taking calcium carbonate oligomers and lipoic acid molecules as examples, macroscopic materials can be formed from hybrid molecules ‘bottom-up’ through the polymerization of ion fragments and the polymerization of disulfide bonds in lipoic acid. Liu Zhaoming said.

The macroscopic material made of this hybrid molecule is the “little yellow button” we eventually see.

There is a mystery within the new structure

The material structure formed by this hybrid molecule is not just as simple as realizing the “hand-in-hand” of inorganic matter and organic matter. Through cryo-EM experiments to do three-dimensional imaging, the research team found that this is a new structure.

In this molecule, the inorganic ionic bond network and the organic covalent bond network are intertwined, “You have me, I have you”. This interspersed network is like a retractable skeleton, which has the properties of inorganic matter and retains the characteristics of organic matter, so it has both hardness and elasticity. When a certain external force is applied, the inorganic skeleton can provide hardness and strength. When the elastic deformation occurs under a large external force, the entire skeleton deformation has a cushioning effect. After the force is removed, the organic skeleton exerts a rebound effect, so that the entire network can be restored to its original state.

“This organic covalent bond network and inorganic ion bond network interspersed with each other structure is not in the past,” Tang Ruikang said, the previous organic matter inorganic fusion, is a simple superposition of the two, such as pouring the inorganic powder into the framework of organic matter, and then stirring evenly, if the layer is subdivided, to the molecular level, it is still “you belong to you, I belong to me”, so more precisely, just a mixture of the two, “Our experiment produced a new molecule that was not in the past, so we got a completely new structure.” It breaks the barrier between organic compounds and inorganic compounds at the molecular scale, and subverts the previous understanding. ”

The “pentagonal warrior” is all-powerful

This new achievement, in short, is that researchers have created a new molecule by stitching together molecular units containing organic and inorganic matter, thus constituting a new material world.

Concept diagram of elastic ceramic plastic with double continuous network. (Photo courtesy of the research group)

This new substance that breaks cognition is an intertwined organic covalent and inorganic ion network at the molecular level, of which the chemical proportion of organic matter and inorganic matter accounts for about half, and in terms of macroscopic materials, it is a composite plastic with both rubber and ceramic characteristics.

Scientists from Zhejiang University compared the performance of this new substance with representative ceramics, rubber, plastics, and metals, and found that it has reached high scores in several indicators such as hardness, springback, strength, deformation and processability, both the hardness of marble, the elasticity of rubber, and the plasticity of plastics, and there is also a characteristic that traditional plastics do not have: it will not soften after heating. The power is so powerful that it can be described as a “pentagonal” warrior.

Tang Ruikang said: “From new molecules to new structures to new materials, we have opened up a new world. ”

Talking about the next step, Tang Ruikang said that new molecules, new structures and new materials are expected to be applied in many research fields from basic chemistry to material science, and also leave more room for imagination for future scientific research.

The project has been funded by the National Natural Science Foundation of China, the National Key Research and Development Project, and the Basic Research Business Fund of Central Universities. (Source: Cui Xueqin, China Science News)

Related paper information:https://doi.org/10.1038/s41586-023-06117-1



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