Upcycling of waste PET into high-performance and multifunctional materials

Recycling waste plastics has brought a global upsurge, but there are still troubles of high-energy consumption and low utilization rates in the recovery process. Here, we present a low-energy consumption route for recycling waste PET into high-value-added and high-performance materials. Bis(2-hydroxyethyl) terephthalamide (BHETA) containing several polar groups is obtained by aminolysis of PET under mild conditions and it is prepared as a BHETA-based adhesive with considerable urethane bonds. Outstanding adhesion properties (1.34 MPa) are maintained in different climatic conditions and organic solutions. To further improve the mechanical properties of the adhesive, subsequently, a multifunctional adhesive with abundant cross-linking structures driven by hydrogen bonding and π-π stacking interactions was prepared by introducing PEG400, which exhibits strong adhesion strength of 2.5 MPa on wood and has excellent sealing performance underwater. Furthermore, the adhesion strength of the adhesive to the wood did not decay significantly after 10 cycles. Benefiting from the above-mentioned adhesion and recyclability advantages, BHETA can also be developed into a high-density rigid foam with remarkable compression resistance (2.1 MPa), which does not lose its compressive strength over a long period of time. This novel recycling strategy offers a new idea for the efficient utilization of degraded products from waste PET.