All-In-One Epoxy/MXene Nanocomposites with Bead-Type Polymeric Imidazole Latent Curing Agent for Enhancing Storage Stability and Flame Retardancy

Abstract

Developing a single-component epoxy system is challenging but crucial for advanced thermoset applications. Unfortunately, conventional latent curing agents using chemical or physical passivation do not provide satisfactory storage stability and the necessary property requirements. Here, it is demonstrated that all-in-one epoxy/MXene nanocomposite system, comprising epoxy resin, polymeric imidazole latent curing agent beads (PILCAB), and Ti3C2Tx MXene, exhibits excellent storage stability, improved flame retardancy, and enhanced mechanical strength. PILCABs, prepared through a Diels？Alder (DA) crosslinking reaction between furan groups of poly(imidazolyl methacrylate)-random poly (furfuryl methacrylate) (PIm-r-PFu) copolymer and bismaleimide (BMI), exhibit excellent storage stability, as stable as under 60 °C storage due to the imidazole reactivity being suppressed synergistically by both physical and chemical passivation mechanisms. Ti3C2Tx MXene flakes, surface-functionalized with alkylated 3,4-dihydroxyl-L-phenylalanine, exhibit excellent compatibility with the epoxy matrix. Consequently, the enhanced storage stability, flame retardancy, and mechanical strength of the all-in-one epoxy/MXene nanocomposite are attributed to the strong DA bond formation in latent curing agent, efficient charring capability of MXene and BMI, and the catalytic effect of the MXene. This study opens new avenues for designing and developing single-component epoxy systems that satisfy demanding requirements, including storage stability, mechanical strength, and flame retardancy, which are essential for practical applications.