Chinese chemists had sumasailalim polymer: if you cut a sample of such material in half and then put two parts close to each other, after 10 minutes it will be whole again. Recovery may occur under severe conditions: in the alkali or the acid as well as at low temperature. In this case, no energy from the outside — heat, light, pressure is required. All this is possible thanks to the combined action of three different linkers — linking groups, which are glued together polymer chains. The results of a study published in Nature Communications.
The tissue of living organisms (skin, muscle) can somosaguas, that is, restore its structure after damage. Now scientists are working on recreating a similar effect in the artificial — most often a polymeric material. Primarily such materials are needed as a basis for electronic skin and artificial muscles, they can also find application in flexible Wearables and other devices. However, most artificial sumasailalim materials yet has one common drawback: in order to run the recovery sample, need external energy — light, heat or mechanical. Therefore, the process of self-healing could not be considered fully Autonomous.
Jing Yang (Jing Yang) and lei Zhang (Lei Zhang) from the University of Tianjin, together with his colleagues managed to obtain a polymeric material that can repair themselves — without the influx of energy from outside. In search of the optimal formula they synthesized seven different polymers. The basis for each was a long chain of polydimethylsiloxane (PDMS), to which was added various linkage groups (linker). When the polymer interacts with the linker, they are firmly glued together, the ends of his chains, resulting in longer polymer. Unlike the usual polymers (e.g., polyethylene) such compounds do not possess a regular structure: long chain dimetilsiloksana and compact bridge groups located randomly.
The authors used three different linker: aromatic disulphide (SS), which is composed of bridging ties, sulfur-sulfur, derived bipyridine (BNB), which can form hydrogen bonds, as well as isophoron diocesano (IP), which can also form hydrogen bonds, but weaker. The proportion of polydimethylsiloxane and linkers varied — a total of seven different compositions of polymer