Fully biobased, catalyst-free vitrimers from tannic acid: a facile combination of mechanical robustness, recyclability and sustainability

Vitrimers are an emerging solution to the problem of plastic pollution including thermoset recycling, due to the embedded dynamic bond exchange reactions during their reprocessing. However, it remains a significant challenge to obtain vitrimers that combine high mechanical strength and enhanced recyclability within a fully sustainable and green framework, especially directly from commercially available biomass. Herein, we report the preparation of catalyst-free, fully biobased vitrimers with high mechanical strength and recyclability obtained from tannic acid (TA), epoxidized vegetable oils (EVOs) and maleic anhydride (MA). The vitrimers exhibited tensile strength ranging from 21.9 to 52.4 MPa. The vitrimers were able to withstand at least 3 rounds of mechanical recycling while still maintaining a tensile strength greater than 10 MPa. The unique branched poly-ring structure of tannic acid is responsible for the perfect combination of robust mechanical properties and good re-processability, permitting the formation of a hyperbranched network that possesses both high mechanical strength and chain mobility. The study also investigated typical viscous behaviors and potential applications including welding, shape memory and scratch healing. The unique hyperbranched structure formed from tannic acid provides both robust mechanical properties and catalyst-free recyclability to fully biobased transesterification vitrimers.