Conventional epoxy polymers are constructed by petro-based resources that are toxic and nonrenewable, and their permanent cross-links make them difficult to be reprocessed, reshaped, and recycled. In this study, a unique eugenol-derived epoxy (Eu-EP) is synthesized, and then vitrimeric materials are prepared by reacting Eu-EP with succinic anhydride (SA) at various ratios (1:0.5, 1:0.75, and 1:1) in the presence of zinc-containing catalysts. All vitrimers exhibit excellent shape changing, crack healing, and shape memory properties. Although vitrimers with 1:0.75 and 1:1 ratios cannot be physically reprocessed, they can be well reprocessed by the chemical method of being simply decomposed in a benign ethanol solution without loading additional catalyst. The collected decomposed polymers can form vitrimers again after exposure at 190 °C for 3 h. This work combines the concepts of vitrimer preparation, chemical recycling, and biobased polymer together, which would bring a feasible way to satisfy the demands of sustainability.

Early epoxy vitrimers in the literature rely on an inequivalent epoxy/anhydride stoichiometry and a large amount of catalyst to achieve a decent transesterification rate within the crosslinked network. This design approach raises a number of concerns such as poor miscibility of the catalyst with other ingredients, poor mechanical properties owing to insufficient crosslinking, the toxicity of the catalyst, etc. In this study, a hydroxyl-amine compound, triethanolamine (TEOA), is incorporated as a catalytic co-curing agent to a typical BPA epoxy–cyclic anhydride curing system to give a TEOA-mediated covalent adaptable network system. The hydroxyl groups and tertiary amine of TEOA catalyze the curing process, and the tertiary amine and the regenerated hydroxyls in the crosslinked network accelerate dynamic transesterification. The resulting epoxy vitrimer exhibits a high glass transition temperature (∼135 °C), excellent tensile strength (∼94 MPa), and fast repairing rate (10 min at 190 °C). Recycling of the TEOA-mediated epoxy vitrimer and reuse of the recyclate are also studied. In an experiment, the vitrimer is ground into powder, and in another, it is degraded in an aqueous solution. The recyclates collected from both experiments are incorporated into the fresh resin, and the new vitrimer materials exhibited similar T gs and moduli to that of original vitrimer samples. This work provides a solution to eliminate the performance gap between conventional epoxy and epoxy vitrimer and offers simple recycling methods of epoxy vitrimer for new epoxy.

Epoxy vitrimers prepared from anhydride‐cured epoxies exhibit, repairable and reprocessable properties; however, they generally rely on a large amount of catalyst for accelerating the dynamic transesterification (DTER). If the catalyst loading is not enough, the vitrimer properties will be limited. In this work, a preparation method of catalyst‐free epoxy vitrimer is demonstrated by adding glycerol to an epoxy–anhydride curing system. The hydroxyls of glycerol first react with the anhydride to induce the ring‐opening of anhydride and form a carboxylic acid, and the latter attacks the epoxy and form a β‐hydroxyester linkage, so the curing can be performed in the absence of catalyst. A significant amount of hydroxy groups are preserved in the crosslinked network, and they serve as both reacting moiety and catalyst for the DTER, which imparts fast relaxation and satisfactory repairability to the materials. By taking advantage of this mechanism, a catalyst‐free and self‐healing coating is demonstrated. These findings provide a solution to avoid using catalyst in vitrimer preparation and advance the application of vitrimer in coating. However, the addition of glycerol produces a decrease of the T g of the final materials, which needs to be further addressed in the future study.

This work offers a successful loop-closing strategy for increasing the sustainability and lowering the manufacturing cost of epoxy materials.

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Utilization of low-value agricultural waste for polymer composite materials has great environmental and economical benefits. Sunflower head residue (SHR) as an agricultural waste may be used as a reinforcement in polymeric materials because of its fiber characteristics. In this work, composites of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and SHR were prepared via melt-extrusion compounding. To improve interfacial compatibility, maleic anhydride (MA) grafted PBAT (PBAT-g-MA) was prepared and used as a compatibilizer for the PBAT/SHR composites. The effects of the concentrations of SHR and PBAT-g-MA on the morphology, mechanical properties, melt rheology, and water resistance of the composites were examined. Interfacial adhesion between phases in the PBAT/SHR composites was enhanced by the introduction PBAT-g-MA as interface-strengthening agent, resulting in improved mechanical properties and moisture resistance of the composite. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44644.