Fluorine-Based Strong and Recyclable Biobased Epoxy Vitrimer for Application in Carbon Fiber Reinforced Composites

Introducing dynamic covalent bonds into epoxy resins to endow them with self-healing, recyclable, and reprocessable properties is of significant importance for extending service lifetimes and addressing environmental issues caused by epoxy resin waste. However, resolving the contradiction between the mechanical properties and the repair efficiency is still highly challenging. In this work, a robust, recyclable, multifunctional biobased epoxy vitrimer (ESFB) was prepared by soybean oil and the fluorinated curing agent 2,2′-dithiobis (6-fluorobenzoic acid) (DTFB). The introduction of the fluorine motif formed fluorine–hydrogen bonds, enabling improvement of the mechanical strength of epoxy vitrimers, while the electron-withdrawing effect of fluorine atoms accelerated the exchange of dynamic bonds, thus improving the reprocess performance. The developed ESFB showed high tensile strength (32.1 MPa), excellent self-healing efficiency (96.8%), and reprocessability compared with its nonfluorinated counterpart (ESLB). Owing to the dynamic exchange characteristics of disulfide and ester bonds, the obtained biobased epoxy vitrimer also demonstrates multifunctional properties, including shape memory effect, weldability, and degradability. Taking advantage of the above features, the carbon fiber/epoxy resin-based composites were prepared based on ESFB. The composites exhibited excellent tensile strength (133.2 MPa), and the carbon fiber can be achieved through nondestructive recycling at 50 °C with a recycling time of only 4 h. In conclusion, this research provides a perspective on the design of high-performance and multifunctional biobased epoxy composites.