Robust Biobased Vitrimers and Its Application to Closed-Loop Recyclable Carbon Fiber-Reinforced Composites

Vitrimers are being actively studied as sustainable plastics. To that end, robust vitrimer films fabricated from a ternary aqueous solution of tannic acid (TA), boric acid (BA), and polyvinyl alcohol (PVA) are reported herein. The trimeric vitrimer films include B–O–C dynamic covalent bonds. The optimal vitrimer film exhibits excellent crosslinking density (0.0471 mol/cm3), tensile strength (77 MPa), and modulus (3.2 GPa). A carbon–fiber-reinforced vitrimer (CFRV) was prepared with a vitrimer film and carbon fiber at temperatures above Tv. The CFRV (tensile strength, 570 MPa; modulus, 21 GPa) can be used as a structural composite material. Additionally, it retains the unique recyclability and reprocessability of the vitrimer. The solution-cast film can be reproduced from the vitrimer solution prepared during recycling, and a CFRV similar to the original can be recreated by remolding the recovered carbon fiber with the reproduced vitrimer film. The synthesized biobased high-strength vitrimer films can facilitate the development of sustainable carbon–fiber-composite materials.