Reversible Diels–Alder Cycloaddition for the Design of Multifunctional Network Polymers

Room-Temperature Healing of a Thermosetting Polymer Using the Diels−Alder Reaction

“…Physical bonding is caused by solvent-mediated swelling and interlocking, whereas chemical bonding results from the thermoreversible Diels-Alder reaction of furans and maleimides. This reaction forms a ring structure below 60°C and reforms the respective diene (furan) and dienophile (maleimide) above 90°C, which is shown in Figure 1 (19)(20)(21). The thermoreversible nature of the Diels-Alder reaction has been previously demonstrated at these temperatures with NMR and FTIR, among other characterization methods (20,22,23).…”

The Effect of Molecular Weight on the (Re)-Processability and Material Properties of Bio-Based, Thermoreversibly Cross-Linked Polyesters

“…The DSC results indicate that after multiple heating cycles, the conformation of the formed adducts gradually shifts from endo to exo, resulting in the higher thermal stability of the adducts, as evident from the shifting of the DSC RDA peak to higher temperatures. The shift from endo to exo configurations at higher temperatures is confirmed by multiple sources [45][46][47][48][49], often accompanied by NMR studies on model compounds. Figure 4 shows the NMR spectra of PE-fur and bismaleimide after several stages.…”

“…It is well known that the DA reaction of furan and maleimide forms a stereoisomeric mixture. Initially, the kinetically-favored endo adduct is formed though at higher temperatures, the thermodynamically favored exo conformation is obtained [45][46][47]. Hence, after heating the material above the rDA temperature, the more stable exo adduct will mainly be formed upon cooling down from a high-temperature starting point.…”