Science subjournal: academician Tian He of Huali and Professor Qu Dahui reported a new generation of high-performance supramolecular polymer simply prepared

Recently, science advanced, a comprehensive sub Journal of science, an international top academic journal, reported on-line the important progress of academician Tian He and Professor Qu Dahui's research team on supramolecular polymers in the form of research papers in the joint research center of felinga Nobel Prize scientists, School of chemistry and molecular engineering, East China University of science and technology molecule for stretchable,self-healing and adhesive supramolecular polymers ”（ DOI: 10.1126/sciadv.aat8192 ）。 The development of high-performance polymer materials is of great significance to meet the growing needs of human production and life Although scientists at home and abroad have developed a series of polymer materials with excellent properties, which respectively show plasticity, extensibility, self-healing, adhesion, and recyclability However, in order to achieve these complex properties and functions, people often need to increase the complexity of their polymer system, which undoubtedly increases the difficulty and cost of material synthesis Therefore, reducing the complexity of the system and increasing the properties of the materials have always been the key trade-off points in the design and development of polymer materials The bottleneck of the research is how to use simple and easily available materials to obtain polymer materials with excellent properties through simple preparation methods Fig 1 Supramolecular polymer synthesized from lipoic acid and its main properties (source: science advances) lipoic acid is a small molecule of natural biological origin, which exists in the form of coenzyme in animals and plays an antioxidant role As a common nutriment, it is a kind of low-cost, easy to get and biocompatible small molecule compound Because the five membered ring with disulfide bond at its end can often be modified to the surface of precious metal as a ligand, thiooctanoic acid and its derivatives are often used by chemists to synthesize and stabilize some nano metallic colloids When the team applied it to the protective ligands of nanoparticles, they found that the synthesized lipoic acid and its derivatives were very easy to spontaneously become insoluble polymers at high concentrations This is due to the strong five membered ring tension and the existence of dynamic disulfide bond of thiooctanoic acid Under high concentration, dynamic covalent ring opening polymerization will take place to form sulfur-containing polymer chain At the same time, a large number of carboxyl groups in the side chain of poly (thiocaprylic acid) can be used as noncovalent hydrogen bonding sites to further associate to form cross-linking network Fig 2 The mechanical properties (source: Science Advanced) of the resulting polymer, which is easy to self polymerize, has attracted the interest of researchers, thus creating a new type of thermoplastic supramolecular polymer that can be formed without solvent The synthesis method is very simple By directly heating and melting the commercial thiooctanoic acid powder, a dynamic thiooctanoic acid liquid is obtained Then a small amount of commercial covalent crosslinker diisopropenylbenzene and non covalent crosslinker trivalent iron ion are added, and the reaction is stirred for 5 minutes and then cooled to room temperature for molding The copolymer obtained by this method is a yellow transparent solid soft material Its unique three-dimensional network structure has three different dynamic chemical bonds, dynamic covalent disulfide bond, non covalent metal carboxyl coordination bond and hydrogen bond The existence of these three kinds of dynamic covalent bonds makes the whole copolymer exhibit excellent mechanical properties Its elongation at break is over 15000% and shows a high Young's modulus After serious damage (3 / 4 of the diameter of the incision), the copolymer can still stretch to more than 110 times of its initial length without fracture Due to its highly dynamic structure, the polymer can spontaneously self repair at room temperature, and the original mechanical strength and elongation at break can be restored in 5 minutes At the same time, the copolymer was also found to be able to be used as a reusable super molecular adhesive, which has strong adhesion to a variety of materials including glass and Teflon, and can be recycled through a simple heating cooling process This work has been highly praised by both editors and reviewers: "this article is very interesting in technology The simplicity and generality of this synthesis method can arouse a lot of research interest." Fig 3 The paper on the adhesion properties of the polymer (source: science advances) was completed by Zhang Qi, Ph.D student of feilinga Nobel Prize scientists joint research center of East China University of science and technology, and Shi Chenyu, an undergraduate, under the guidance of Professor Qu Dahui, academician Tian He and academician Ben L Feringa, Nobel Prize winner in chemistry Prof long Yitao and associate researcher Hua Xin support the material testing The research was supported by NSFC innovation groups, major projects and 111 talent introduction program.