Self-Healing Functional Materials Based On Coordination Bonds

The damage of polymer materials will lead to waste of resources,material failure,and even some safety accidents.The self-healing property of polymer materials can extend its service life and improve their safety/stability.However,in the field of self-healing polymeric materials,especially in the field of supramolecular self-healing materials still exist some problems,such as the development of the self-healing polymers with excellent mechanical properties and good self-healing performance,the development of functional self-healing materials,the development of the self-healing polymers that suitable for the harsh environment.The above problems restrict the practical application of supramolecular self-healing materials.Coordination bonds are an effective means to design new self-healing materials due to spontaneously forming bonds,adjustable bond energy,combination of thermodynamic stability/kinetic lability and functionalization.In this paper,the simple and effective strategies were utilized to study following three problems by using coordination bonds.First,the supramolecular self-healing polymer networks with excellent mechanical properties and good self-healing properties were designed by using Zn2+-imidazole coordination bonds;Second,supramolecular self-healing block polymer networks with excellent mechanical properties and good self-healing properties were obtained via incorporating lanthanide ion(Eu3+/Tb3+)-isophthalic acid coordination bonds with the structure design of polymers,and the fluorescence properties were also given;Third,supramolecular self-healing polymer networks that can responsively self-healing in seawater is developed by using Ca2+/Mg2+(in seawater)-isophthalic acid coordination bonds,and it is applied to the flexible tail of bionic fish,which expands the application prospect of supramolecular self-healing materials.To obtain supramolecular self-healing materials with excellent mechanical properties and good self-healing properties,the coordination bonds and urea hydrogen bonds were introduced into the supramolecular networks.Polymer P1,P2 and P3 were obtained by RAFT polymerization(Reversible Addition-Fragmentation Chain Transfer Polymerization).Then,Zn2+ was introduced into the system to obtain the self-healing polymer materials(P/Zn-a,P/Zn-b and P/Zn-c)with the dual dynamic interaction of Zn2+-imidazole coordination bonds and urea-hydrogen bonds.The Zn2+-imidazole coordination bonds have an important influence on the mechanical properties of the self-healing polymer,which gives the system excellent and adjustable mechanical properties.The mechanical properties of self-healing polymers can be easily regulated by the content of Zn2+-imidazole coordination bonds in the system.In addition,the Zn2+-imidazole coordination bonds and the presence of urea-hydrogen bonds in the system give the polymer good self-healing properties.The results of situ FT-IR spectroscopy clearly confirmed the reconstruction of the dual dynamic supramolecular interactions with increasing temperature,indicating that the excellent mechanical properties and good self-healing properties are attributable to the dual dynamic interactions.The supramolecular self-healing material Poly(MMA-co-BA-co-IUA)/Zn-a with excellent mechanical properties and good self-healing properties was obtained by optimizing the experimental conditions.Based on above self-healing polymer,a conductive self-healing film is obtained,which is expected to be used in self-healing wearable devices.Special functions can make supramolecular self-healing materials with both excellent mechanical properties and good self-healing ability more attractive.In this chapter,fluorescent supramolecular self-healing block materials P(BA-co-IPA)-b-PStx-Eu3+-y with excellent mechanical properties and good self-healing properties was obtained by combining coordination bonds with the structure design of polymers.The mechanical properties of the system could be easily adjusted by adjusting the content of the Eu3+-isophthalic acid coordination bonds.The supramolecular self-healing block materials have mild self-healing conditions and high self-healing efficiency.The excellent mechanical properties and self-healing properties are attributed to the introduction of Eu3+-isophthalic acid coordination bonds and the design of block structure.Lanthanide ion(Eu3+/Tb3+)-isophthalic acid coordination bonds can also give the supramolecular self-healing block materials excellent and adjustable fluorescence properties.The fluorescence properties are tunable through changing the molar ratio of Eu3+/Tb3+in the system,which is expected to be applied in the fields of UV excited fluorescent anti-counterfeiting/encryption ink.The ultimate goal of developing new and reliable supramolecular self-healing materials is to meet the practical application.Thus,it is necessary to endowing them with the self-healing ability under harsh environment.In this section,supramolecular self-healing materials(poly(BA-co-IPA)and poly(BA-co-IPA)-Fe3+-1)with responsive self-healing in seawater were obtained by coordination bonds due to the important application prospect of self-healing polymer materials in the marine environment.When damaged,the isophthalic acid groups responsively uptake calcium and magnesium ions from the seawater for coordination bonds to complete the repair.EDS results show a certain amount of calcium and magnesium ions appeared in the scratches of the film after being immersed in seawater for 24 hours,which proved the responsive self-healing in seawater.In addition,swelling experiments show that the responsive self-healing film is stable in seawater.The flexible tail of bionic fish was made by using this responsive self-healing film.The damaged flexible bionic tail could be spontaneously self-healed in seawater and drive the bionic fish to normally swim in seawater.Bionic fish could be used to detect pollutants in seawater or biological monitoring,even for military reconnaissance.In this paper,three problems in the field of supramolecular self-healing materials have been studied and made some achievements.The coordination bonds between special functional groups and metal ions was utilized to endowing the supramolecular self-healing materials with excellent mechanical properties and good self-healing properties,fluorescence performance and responsive self-healing ability in seawater.We expect that more new supramolecular self-healing materials will be developed and applied in future studies inspired by the supramolecular self-healing polymer networks designed in this paper.