Self-repairing rubber
Rubber materials are usually long molecules in the form of chains. For their formation smaller molecules (monomers) are joined by covalent bonds. In addition, they are elastic, that is, if deformed they recover the original form. However, if the chain is cut at some point, it is impossible to tie these two ends, at least under normal environmental conditions. A group of Parisian chemists, led by Ludwik Leibler, has synthesized a rubber that is cut and repaired on its own.
The secret is the monomers he has used to form the rubber. Instead of joining each other through covalent links, they form hydrogen bridges. Hydrogen bridges are much weaker than covalent bonds. They are not chemical bonds, but attraction forces derived from intermolecular interaction.
Unlike covalent bonds, hydrogen bonds can be performed and broken down at room temperature. This gives special properties to the material they have generated. It is, among other things, a very elastic material (it can be lengthened up to five times the natural size and in a minute it returns to the original size) and, if broken, broken joints can be repaired. The simple juxtaposition of the broken ends allows the reconstruction of the hydrogen bridges, thus recovering the rubber we had before its breakage.
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