Study On Epoxy Resin Self-Healing Materials Based On Dynamic Covalent Bond And Host-Guest Interaction

Epoxy resin has the advantages of easy curing,strong bonding,excellent mechanical properties,good heat and corrosion resistance,etc.It is widely used in many fields such as construction,railway,military and aviation.However,most epoxy resin materials also have the disadvantage of great brittleness.In the long-term use process,cracks are often generated due to the stimulation of external conditions,which seriously affects the use of epoxy resin materials.The research shows that the intrinsic selfhealing strategy can effectively prevent the appearance and expansion of cracks,prolong the service life of epoxy resin,and reduce the waste of resources.Compared with other intrinsic self-healing,reversible reaction of disulfide bond and host-guest interaction have the advantages of mild reaction conditions,low raw material price and no need for catalyst.Meanwhile,epoxy resin based on these two self-healing principles has the ability of multiple self-healing.Based on the advantages of reversible disulfide bond and host-guest interaction self-healing epoxy resin,this paper started from the design of the composition structure,mainly adopted the strategy of curing agent and epoxy resin to introduce self-healing units to prepare epoxy resin with high self-healing efficiency,studied its self-healing mechanism,and explored strategies to improve the self-healing efficiency and mechanical properties of epoxy resin.The main research contents are as follows:The first part is the preparation of self-repairing epoxy resins with disulfide bonds.An amine-based curing agent with a double-sulfur bonded self-healing unit was prepared by reacting dimethyl dithiodipropionate with polyetheramine,and this curing agent was used to cure with the epoxy resin to prepare a self-healing epoxy resin(PDEP)with a double-sulfur bond.Through the characterization of structure and properties,it was found that when the ratio of polyether amine to dimethyl dithiodipropionate was2:1,the self-repair efficiency of PDEP could reach 98%,and the self-repair efficiency could still reach more than 90% after three times of repair.The excellent self-healing properties come from the reversible reaction of disulfide bonds.In addition,the introduction of polyether amine greatly improved the toughness of epoxy resin,and the maximum elongation at break of PDEP was found to be about 800%.The second part is to introduce the host-guest self-healing unit into the curing agent,and then to prepare the host-guest self-healing epoxy resin(CAEP)through the curing reaction of epoxy resin.Through the performance test,it is found that the content of host-guest and the flexibility of epoxy resin jointly affect the self-healing efficiency.When the content of host-guest is 1%,the self-healing efficiency of CAEP can reach 89%.With the increase of host and guest content,the mechanical properties of CAEP also improved.The third part is to prepare multiple self-healing epoxy resin(PCEP)with both disulfide bond self-healing unit and host-guest self-healing unit by mixed curing agent.The synergistic effect of reversible reaction of disulfide bond and host-guest interaction improved the self-healing efficiency of epoxy resin as a whole,and the self-healing efficiency of PCEP in all proportions was above 70%.