Preparation Of Epoxy Vitrimer And Its Interfacial Reaction Behavior With Linear Polymers

The dynamic crosslinking network structure of Vitrimer makes it combine the advantages of both traditional thermoplastic and thermosetting plastics,that is,it has outstanding repeatability on the premise of excellent mechanical properties.Therefore,it shows great application potential in many fields such as shape memory,bonding and reprocessing.However,most of the current studies on Vitrimer focus on synthesis and preparation,and little attention is paid to its performance regulation and interface behavior.In this paper,different kinds of epoxy Vitrimer were prepared and their interfacial diffusion kinetics with linear polymers were studied in order to provide theoretical basis and technical support for the application of such polymers in self-healing and bonding fields.The research results are as follows:（1）Performance regulation of epoxy Vitrimer:The factors affecting the performance of epoxy Vitrimer are explored by changing the type and dosage of crosslinking agent and catalyst and adding toughening agent.The longer the molecular chain of crosslinker,the better the toughness of epoxy Vitrimer prepared.The elongation at break of DT2.5 catalyzed by 2.5 mol%1,5,7-triazidicyclic[4.4.0]decan-5-ene（TBD）with dodecanedioic acid（DA）as crosslinker is about 330%higher than that of GT2.5 prepared with glutaric anhydride（GA）as crosslinker.The type and amount of catalyst affect the exchange reaction rate,and excessive catalyst will reduce the fracture strength of the material.Epoxy soybean oil（ESO）can effectively improve the toughness of epoxy Vitrimer,and the elongation at break（GT2.5）of GE12 prepared by adding 12 mol%ESO to GT2.5 increases 84%.The prepared epoxy Vitrimer has excellent shape memory effect.（2）By studying the interfacial reaction between epoxy Vitrimer and amino-terminated polystyrene（PS-NH₂）,it was found that:With the extension of annealing time,the interface layer with the width of tens of nanometers is formed at the interface.The chemical composition and mechanical properties of the interface layer are between epoxy Vitrimer and PS-NH₂,and the interface layer presents a stepped change with the change of the width.The width of interfacial layer is related to the molecular weight of PS-NH₂.After 1920min annealing at 195℃,the interfacial width of PS-NH₂ with molecular weight of9K is 424%wider than that of PS-NH₂ with molecular weight of 300K.Under the same annealing condition,when the catalyst loading in epoxy Vitrimer is7.5 mol%,the width at the interface of the double-layer sample is 11.6%wider than that at 2.5 mol%.