Ultra-Fast Microwave Assisted Self-Healing of Covalent Adaptive Polyurethane Networks with Carbon Nanotubes

Vitrimers are a class of covalent adaptive networks which, unlike other covalent networks, can be thermally reprocessed, recycled, and are self-healing. In this research, a polyurethane vitrimer network is prepared using 1,4-phenylene diisocyanate and excess amount of polycaprolactone polyol. The dynamic nature of this network is provided by a dual effect of dynamic transesterification reactions as well as dynamic transcarbamoylation reactions. This vitrimer can be reshaped, be recycled, and heal potential defects at high enough temperatures. A fast healing strategy is developed by the addition of small amounts (0.05 wt%) of carbon nanotubes (CNTs) which enables the use of microwave radiation for an efficient fast healing process. Using this strategy the healing time decreases more than 30 times compared to using a conventional oven. CNTs also enhance the vitrimer mechanical properties and compensate for the mechanical property loss of the dynamic PU network in comparison to the permanent PU network.