Reprocessable Shape Memory Epoxy Resin Based on Substituent Biphenyl Structure

Abstract

which had good thermal ability with glass transition temperature (T g ) about 150 °C. Zhang's group synthesized a series of regular rigid-flexible crosslinking epoxy networks, which had excellent shape memory performance and storage modulus was over 900 MPa. [14] Krajnc's group prepared epoxy-benzoxazine copolymers, which possessed strong shape-memory ability and whose stiffness was enhanced. [15] Nevertheless, the irreversible covalent cross-links in the above epoxy resins make their reprocessability inherently arduous. Given the significance of shape memory epoxy resin in practical applications, the lack of reprocessability hinders the development of epoxy resin. Consequently, it is highly desirable to develop reprocessable SMPs, aimed at achieving sustainable development. [16] The incorporation of dynamic covalent bonds into SMPs offers a feasible solution. Dynamic covalent bonds can be broken and reformed reversibly in response to external stimulus, [17] endowing thermosetting polymers with reprocessability. Efforts have been made to fabricate the reprocessable shape memory epoxy resin through feasible synthetic routes. Lei's group prepared a reprocessable shape memory epoxy resin containing siloxanes, which had good shape memory performance with R f of 91.5%, R r of 85.9% and the strain about 5%. [18] Liu's group synthesized a reprocessable shape memory epoxy resin with the reaction of epoxidized soybean oil and fumaric acid, which exhibited high R f of nearly 98%, R r of nearly 89% and the strain about 6%. [19] Li's group fabricated a reprocessable epoxy resin from epoxy soybean oil and glycyrrhizic acid, which completed the shape memory cycles, with R f about 92% and R r about 94%. [20] Despite much progress in achieving good reprocessing performance in shape memory epoxy resin, the reprocessable epoxy resins mentioned above are usually limited to low shape recovery, poor repeatability, and small strain. Thus, SMPs can realize good shape recovery and good repeatability, which is challenging but exceedingly important. Some special structures have been designed to improve the shape memory performance, such as including well-controlled network structure, [21] semiinterpenetrating network structure, [22] liquid crystal unit, [23] star network structure, [24] and topological slide-ring structure. [25] For instance, our group synthesized topologically well-controlled poly(ethyl methacrylate) structures [21] and semicrystalline slidering shape-memory polycaprolactone-based polyurethane network, [25] which both showed excellent shape memory performance. Li et al. also studied PMMA/PEG semi-interpenetrating network [26] and PMMA-PCL copolymer networks [27] possessed Despite significant progress in realizing the reprocessability in epoxy resins, it is very meaningful to develop a reprocessable shape memory epoxy resins with excellent shape recovery properties and good repeatability. In this work, a reprocessable shape memory epoxy resin based on substituent diphenyl structure is synthesized successfully via solution...

Developing Reprocessable shape memory thermosetting resins with high thermal resistance and strength through building a crosslinked network based on bismaleimide and epoxy resins

“…Epoxy resin is the most representative type of thermosetting resins and occupies about 70% of the whole market of thermosetting resins, 23 so SMPs based on epoxy resin have attracted great interest, 17,22,24–26 however, these SMPs generally have low heat resistance and insufficient mechanical strength 18,20–22,24,27–31 …”