Biobased Aliphatic Polyurethane Vitrimer with Superior Mechanical Performance and Fluorescence-Based Defect Diagnostic Function

Thermosetting polyurethanes generally have robust mechanical properties, good chemical resistance, and biocompatibility. However, they suffer difficulties in repairing or recycling once they served their initial purpose as a result of their cross-linked structure. Hence, we report an unconventional catalyst-free polyurethane vitrimer (PUV) prepared from a bio-based feedstock. The obtained compounds have abundant carbamate linkages, and the dense hydrogen bonds between carbamates and hydroxyl groups contribute to the impressive tensile strength and impact energy absorption values of 76.8 MPa and 60.4 kJ/m2, respectively. In addition, rich carbamate bonds and free hydroxyl groups present in the network enable a thermally induced intrinsic dynamic carbamate interchange reaction (referred to as transcarbamoylation) (DCIR) without the need of the catalyst. With the highly efficient DCIR, the damaged PUV film can be repaired fully at 160 °C in 10 min, and its fragments can be recycled into an integral film via hot pressing at 180 °C in 2 h. Also, the application of PUV is demonstrated with a fluorescent indicator film, the damages and defects on the surface of which are easily detectable and repairable. Overall, this work proposes a simple strategy for preparing a catalyst-free high-performance PUV from bio-based alcohols and demonstrates its potential use in high-performance film applications.