Multifunctional polyurethane-vitrimers completely based on transcarbamoylation of carbamates: thermally-induced dual-shape memory effect and self-welding

Environmental protection and resources exhaustion have become the two major obstacles that the human race faces. Moreover, conventional thermoset polymers, which have been extensively applied in various fields, are difficult to be reprocessed and recycled thereby resulting in a wastage of resources and environmental pollution owing to their chemical crosslinks. Therefore, vitrimers may be a good option to solve this problem. In this study, renewable castor oil was used as the raw material to synthesize multifunctional polyurethane-vitrimers (PUVs), whose intrinsic carbamate bonds undergo transcarbamoylation reactions in the presence of a catalyst. Reprocessing experiments have shown that reprocessed PUVs have nearly the same excellent tensile property compared with the pristine PUVs and have significant potential for future engineering applications. Subsequent studies have indicated that crosslinked networks have properties of thermally-induced dual-shape memory effect (dual-SME) and self-welding due to transesterification reactions of carbamate bonds. As the current methods of dealing with abandoned thermoset polyurethanes have drawbacks, it can be anticipated that our findings will create significant benefits for our life.