Preparation And Characterization Of The Self-healing Polymer

Polymer materials will be gradually damaged when they are exposed to the environment,such as sunshine light,UV light,and heat,et al.Those extreme conditions would change the bulk properties of polymer materials,lower their performance,and eventually shorten their service life.Self-repairing,which can be simulated from the healing of damage of living beings,is a new method to solve the damage of polymers and make them more durable.In this paper,recent progress in the area of self-repairing polymer materials is reviewed,which can be divided into self-repairing polymers by covalent bond and self-repairing polymers by supramolecular interaction.Their chemical mechanism and preparation method are discussed thoroughly.Furthermore,except for mechanical properties,other useful properties that need to be self-repaired are also reviewed.Some of those important examples are collected and classified,such as three dimension shape self-repairing,electronic conductivity self-repairing,and hydrophobisity self-repairing of polymer surface.Our research mainly includes the preparation of furanyl polyurethane with furyl alcohol as monomer,and the further reaction with bismaleimide to prepare Diels-Alder DA covalent crosslinked polymers.When the damaged material is heated to a certain temperature,the DA reaction proceeds forward and the covalent bond recombines to achieve the purpose of repairing the material.Due to the difference of monomer and crosslinking agent,the repair temperature of the material is slightly different.The results of DSC and DMA showed that this phenomenon showed certain regularity: the repair temperature of amide monomer was the highest,the imide temperature was the second,and the amines temperature was the lowest.At the same time,in order to improve the repair performance of the material and to further protect the material,we filled the matrix of the self-repairing material with nano-silica loaded with low surface energy substance.The material has hydrophobic ability to achieve self-protection.Moreover,nanoparticles migrate as the chain moves,creating a durable and recoverable hydrophobic surface.In order to attach low surface energy to the surface of silica nanoparticles,we first synthesized diazomethane containing perfluoroalkyl at the end,and then heated diazomethane to form carbene.The surface modification of nano-silica was realized by the insertion reaction between carbene and hydroxyl groups on the surface of silica.By changing the content of nano-silica in polyurethane materials,the effects of nano-silica on mechanical properties and hydrophobic properties were summarized and analyzed.The mechanical repair efficiency of the material was obtained by electron microscope and tensile test.Through the contact angle and surface element analysis and testing,it is proved that the surface properties of the material can be repaired.To sum up,we have obtained a polyurethane composite material which can be excited by the same condition(heat)and can be repaired by both mechanical and surface at the same time.After the material is damaged,the covalent reaction between furan and bismaleimide is carried out in a positive direction after the material is damaged,and the internal mechanical properties of the material are repaired;at the same time,the material is expanded and moved through the molecular chain.The nano-silica nanoparticles are driven to move and migrate to the surface of the cracks to achieve the effect of auxiliary repair of mechanical properties.At the same time,the low surface energy substances and nanoparticles migrate to the surface of the material,which improves the antenna of the material surface,that is,increases the surface hydrophobic ability of the material,prevents the material from being corroded,and then achieves the purpose of protecting the material.