This work reports for the first time the copolymerization studies of 11 newly synthesized epoxidized vegetable oils (EVOs) that reacted with a disulfide-based aromatic dicarboxylic acid (DCA) to produce thermoset materials with recyclability properties. These new EVOs' reactivity and properties were compared with those of the two commercial references: epoxidized linseed oil (ELO) and epoxidized soybean oil (ESO). The structure−reactivity correlation is proposed by differential scanning calorimetry (DSC) analysis, corroborating the epoxy content of EVO monomers, the initiator effect, the copolymerization reaction enthalpy, and the temperature range. The thermomechanical properties of the obtained thermosets were evaluated and discussed in correlation with the structure and reactivity of monomers by dynamic mechanical analysis (DMA), tensile testing, and thermogravimetric analysis (TGA). It has been found that the higher the EVO functionality, the higher is the reactivity, cross-linking density, and final performances, with tan δ values ranging from 34 to 111 °C. This study investigates the chemical recycling and the solvent resistance of these vitrimerlike materials that have a high bio-based carbon content, from 58 to 79%, with potential application in coating or composite materials in the automotive sector.

Bisphenol A-based epoxy thermosets involve both environmental and health risks. By reacting a vegetal oil-based epoxide with an aromatic diacid containing S–S bonds a thermoset is produced. Herein, reprocessable thermosets were synthesized, the recyclability being designed through a dual mechanism: that of disulfide metathesis and of transesterifications. To assess the feasibility of the reprocessing, a series of 10 initiators was tested to probe their effect not only on the cross-linking reaction but also on the recyclability. This study introduces for the first time the key role of the initiator on the material performance and on their reprocessing. A very good reprocessability was obtained for thermosets prepared using as initiator the imidazole. Moreover, the thermosets exhibit complete chemical recyclability in 1 N NaOH at 80 °C, after 3 days, without needing additional chemicals. The reprocessed materials have similar performance with the virgin ones, even after 10 cycles of reprocessing.

In a sustainable development context, epoxidized vegetable oils (EVO) have unlimited and promising future prospects as renewable and environmentally friendly feedstock. The only drawback to their use is their low and non-selective reactivity compared to the aromatic epoxides. Properly, a small optimized amount of “true” initiators can overcome this issue and also beneficially serve in properties such as glass transition, modulus, strength, elongation at break, and chemical resistance. This paper presents efforts to understand and identify the initiator’s effect to more accurately predict how to select a good initiator on EVO/dicarboxylic acid systems. A new bio-based reprocessable epoxy resin was prepared from epoxidized linseed oil (ELO) and 2,2′-dithiodibenzoic acid (DTBA). The evolution of the chemical structures and the reactions’ mechanisms have been systematically studied by in situ Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopies and differential scanning calorimetry (DSC). A screening of 10 initiators was performed for the ELO/DTBA cross-linking reaction. The influence of the initiator’s structure, basicity, and nucleophilicity was assessed and ranked in terms of the kinetic response including the epoxy–acid reaction rate and the percentage of functional group consumption. An excellent effect achieved by imidazole as an initiator was demonstrated. An attempt has been proposed to corroborate the experimental values with the results of quantum chemistry calculations.

The preparation of thermosets based on epoxidized vegetable oils (EVOs) involved a peculiar attention in recent years; however, most of them cannot be recycled once cross-linked. In the present work, epoxy thermosetting resins like-vitrimers with dynamic disulfide covalent bonds were prepared by copolymerizing twelve EVOs with 2,2′-dithiodibenzoic acid, as hardener. Here, we show for the first time the reprocessability, repairability, and recyclability properties of EVOs thermosets. The 3R abilities were evaluated in correlation with the EVO epoxy contents, which influence the final thermo-mechanical properties of the recycled material. The virgin versus recycled materials' comparison was studied by FT-IR, DSC, TGA, and DMA, also comparing their swelling ability and high gel content. The study investigates, in addition, the excellent shape memory properties of the reprocessed EVOs/disulfide materials.

Beyond the need to find a non-toxic alternative to DiGlycidyl Ether of Bisphenol-A (DGEBA), the serious subject of non-epichlorohydrin epoxy resins production remains a crucial challenge that must be solved for the next epoxy resin generations.

Thermoset polymers with permanently cross-linked networks via thermally reversible covalent bonds have outstanding self-healing and adaptable properties, combined with very good mechanical properties and solvent resistance. This work reports in...

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The reactivity of epoxidized perilla oil and epoxidized safflower oil with two aromatic dicarboxylic acids was studied. The presence of S–S bonding at the β position of the carboxylic group increases the reactivity of the acidic proton toward epoxy ring opening.