Preparation and characterization of an azide–alkyne cycloaddition based self-healing system via a semiencapsulation method

Abstract

An azide–alkyne cycloaddition based self-healing system was designed by a semiencapsulation method. Multiwall carbon nanotubes were functionalized with poly(t-butyl acrylate) containing azide end functionality using atom transfer radical polymerization. Subsequently the alkyne counterpart was encapsulated in urea formaldehyde microcapsules and embedded in an epoxy matrix. The healing click reaction was triggered by an embedded copper catalyst. Whenever a damaging event occurs in the epoxy matrix, the liquid cross linker in the presence of catalyst will dissolve the implanted catalyst from the matrix initiating the crosslinking reaction between azide and alkyne and thus healing the cracks. The effects of temperature and healing duration on healing efficiency are investigated. Once healed, the self-healing system recovers as much as 65% of its original fracture toughness.