Diels-Alder Chemistry to Develop Self-Healing Epoxy Resins and Composites Thereof

Abstract

Self-healing polymers are a class of smart materials able to recover after sustaining damage. A family of thermosetting epoxy resins, containing Diels-Alder (DA) adducts in the epoxy precursor backbone, has been prepared and characterized. The DA adducts can be reversibly cleaved and reformed under the appropriate thermal conditions, and this feature has been exploited to produce intrinsically self-repairing materials. This chapter focuses on the effects of different structural features, such as average number of crosslinking functionality and molecular mobility of epoxy precursors, on the efficiency of healing process. High cross-linking density and molecular stiffness improve mechanical performances, such as elastic modulus and glass transition temperature, and allow fabrication of self-healing fiber-reinforced composites by conventional manufacturing technologies. Within this chapter, the molecular design, the preparation, and the evaluation of properties of self-healing epoxy and its composites have been discussed.

Impact of the Chemical Structure of Photoreactive Urethane (Meth)Acrylates with Various (Meth)Acrylate Groups and Built-In Diels–Alder Reaction Adducts on the UV-Curing Process and Self-Healing Properties

“…This reaction is one of the most effective and reliable strategies for producing cyclic hydrocarbons, for which explorers Otto Diels and Kurt Alder won the Nobel Prize in 1950 [ 1 ]. A key element in the synthesis of this type of polymeric material is the incorporation of Diels–Alder adducts into the polymer structure and the use of appropriate adducts, which enable the coordinated cycloaddition of the substituted alkene to the conjugated diene and the possibility of self-repair of the polymer [ 2 , 3 , 4 , 5 ]. Self-healing materials respond to structural damage such as cracks, cavities, and dents.…”

Self-healing materials for potential use in textile and clothing applications

“…Thermosetting epoxy resins containing DA adducts in the epoxy precursor belong to self-healing polymers and form the class of smart materials from which intrinsically self-repairing materials are produced. One of the properties of DA adducts is their ability to be reversibly cleaved and reformed under suitable thermal conditions [69]. The study by Zolghadr et al investigated novel self-healing DA polymers and semi-interpenetrating polymer networks (semi-IPNs).…”