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

Abstract

Self-healing materials are particularly desirable for load-bearing applications because they offer the potential for increased safety and material lifetimes. A furan-functionalized polymer network was designed that can heal via covalent bonding across the crack surface with the use of a healing agent consisting of a bismaleimide in solution. Average healing efficiencies of approximately 70% were observed. The healing ability of fiber-reinforced composite specimens was investigated with flexural, short beam shear, and double cantilever beam specimens. It was found that solvent amount and maleimide concentration play key roles in determining healing efficiency.

Recent advances in fiber/matrix interphase engineering for polymer composites

“…Pioneering activity in this field should be attested to the group of Palmese [145][146][147]. The basic idea was to bring one of the required functional groups onto the fiber surface, whereas the counterpart groups are in the matrix resin.…”

“…Complete recovery of the IFSS was reported for a resin system with a Tg≈6°C. A recent work of the Palmese group [147] addressed the room temperature healing of EP and EP/GF composites via DA reaction. Here the healing was achieved by a combination of solvent-induced swelling and covalent bonding through DA.…”

“…Proposed healing mechanism owing to physical (interlocking caused by solvent induced swelling) and chemical interactions (DA reaction between furan and maleimide functional groups) (based on ref. [147]). Symbols as in Figure 10.…”

“…The related chemical pathway is given in Figure 12. Similar to the approach of the group of Palmese [145][146][147], the EP was furan modified by adding FGE. The healing efficiency was checked by microbond tests.…”

Reversible oligomerization of 3-aryl-2-cyanothioacrylamides via [2s + 4s] cycloaddition to substituted 3,4-dihydro-2H-thiopyrans

“…To achieve intrinsic self-healing abilities of the material, in particular the Diels-Alder (DA) cycloaddition has been applied in many materials, because the original properties of the materials do not change significantly. [1][2][3] Due to the thermal reversibility of the retro-Diels-Alder (rDA) reaction, it is possible to obtain self-healing polymers with well-defined architectures and properties. [4,5] The DA reaction of furan and maleimide is the commonly used functional system for most reversible self-healing polymers of this type.…”