A thermally remendable multiwalled carbon nanotube/epoxy composites via Diels-Alder bonding

Mechanically robust and self-healing epoxy composites are highly desired to satisfy the increasing demand of high-performance smart materials. Herein, a dual functionalized epoxy composite (EpF-MWCNT-PA-BM) with self-healing performance based on Diels-Alder chemistry has been investigated. The furfuryl grafted epoxy (EpF) and furfuryl modified MWCNTs (MWCNT-F) are reacted with bifunctional maleimide (BM) and normal anhydride curing agent (PA) to form a covalently bonded and reversibly crosslinked epoxy composite with two types of intermonomer linkage. That is, thermally reversible Diels-alder bonds between the furan groups of both epoxy and MWNCTs with malemide and thermally stable bonds of epoxide and anhydride groups. MWCNTs act as both reinforcer and a healant in the epoxy composite. In this way, the cured epoxy composite possessed not only enhanced mechanical properties but also thermal remendability that enabled elimination of cracks. The latter function took effect as a result of successive retro-DA and DA reactions, which led to crack healing upto 79.82% healing efficiency in a controlled manner through chain reconnection.