摘要
Diketoenamine bonds have been utilized in building up associate covalent adaptable networks for the preparation of vitrimers with closed-loop chemical recycling features. For further enhancement of their sustainability and properties, a biomass-based diacid, 2,5-furandicarboxylic acid (FDCA), is employed as a raw material for the preparation of the diketoenamine vitrimers in this work. Based on the rigid ring structure of the furan group, the FDCA-based diketoenamine resin shows a high glass transition temperature of 144 degrees C and good mechanical properties (storage modulus at 50 degrees C: 2.7 GP, Young's modulus: 1040 MPa, tensile strength: 54.4 MPa, and elongation at break: 7.1%). The resin exhibits a relaxation time of about 420 s at 170 degrees C and activation energy for stress relaxation of about 69 kJ mol-1, both are higher than the values reported to the aliphatic diacid-based analogues and could be attributed to the rigidity of the furan groups. The resin shows physical recycling and reprocessing features at 190 degrees C as well as a closed-loop chemical recycling properties through acid-catalyzed hydrolysis reaction of diketoenamine bonds. The monomer (FDCA-based triketone) recycling ratio is of about 68%. Moreover, the chemical recycling feature of the FDCA-based diketoenamine vitrimer also contributes to the full recovery of the carbon fibers (CF) from the diketoenamine vitrimer/CF composites. The biomass-based and sustainable vitrimers have potential applications for replacements of conventional cross-linked resins.