| Epoxy resin has excellent dimensional stability,solvent resistance and mechanical properties,and is irreplaceable in many practical applications,such as electronic appliances,automotive and aerospace equipment.However,their stable covalent three-dimensional cross-linking network makes it difficult for them to be re-formed,healed or recycled after being completely cured,which brings about problems such as resource waste and environmental pollution.With the development of dynamic chemistry,dynamic polymer chains are rearranged due to the reversible exchange of dynamic bonds,giving thermosetting materials the same reprocessing,healing or recycling properties as thermoplastic materials.But at present,the dynamic bond polymers with strong rigidity generally need harsh stimulation to show their characteristics,and most of the dynamic bond polymers will lose the stability of the material under a certain stimulation,and then limit their application.In addition,the disassembly conditions of the dynamic bond polymers are relatively harsh and single,which greatly limits their application range.In order to balance the contradiction between dynamic performance and strength of dynamic bonding polymer materials,and to obtain materials with adjustable crosslinking structure or bonding mode to show good stability and multiple stimulation disassembly,the controllable design and comprehensive application of dynamic epoxy resins are very important.Using single dynamic interaction between non covalent cation-π build hard epoxy resin material,because its mode of combination of "point-face",big outer stimulation effect area under the action of dissociation and reconstruction of high efficiency and developed under the medium temperature shows that the dynamic characteristics of epoxy resin,show the condition of 120 ℃ to machining and welding ability,and has 38 MPa mechanical strength,It can be restored to 32 MPa after reprocessing.The rapid removal and reconstruction properties of the cation-π give the material versatility,such as triple shape memory and tension-triggered fluorescence.Based on the study of dynamic non-covalent cation-π,dynamic disulfide bond was introduced into epoxy resin,and different dynamic disulfide bond crosslinking structure of double dynamic epoxy resin was designed.The effect of different crosslinking structure on dynamic properties was studied respectively.First through the choice of functional monomers,the preparation of the dynamic interaction between disulfide bond and cation-π with parallel structure of crosslinked "parallel interlock" double dynamic type epoxy resin,the epoxy resin shows good stability and dismantling a single stimulus selectivity,polymer with a single stimulus is still with the stability of threedimensional crosslinked structure,when two stimulation effect at the same time,Material disassembly can be realized.At the same time,the epoxy resin exhibits excellent mechanical properties（tensile strength 90 MPa,storage modulus 1.37GPa）.Secondly,a class of functional epoxy indole monomers were designed,and a class of series double dynamic epoxy resins with dynamic disulfide bond and cation-π interaction were prepared.Due to the different stimulus responses of dynamic disulfide and cation-π interactions,the series duplex dynamic epoxy resin exhibits multiple stimulus disassembly.When the epoxy group ratio of regulated bisphenol A epoxy resin（DGEBA）to indole（IN）was 2:1,the epoxy resin not only had multiple stimulus response degradation characteristics,but also had good stability and mechanical strength of 53 MPa,and could be reprocessed at 150℃. |
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