The "De-Re Polymerization" Strategy: From Nondegradable Pet to Degradable Peat

Polyethylene terephthalate (PET) is a widely used plastic, but its short service life and non-degradable features make it a major source of white pollution. In this context, the efficient recycling and rational reuse of PET have become a global research priority. In this paper, a deep eutectic solvent(DES?is prepared using methylurea and zinc chloride to catalyze the efficient PET glycolysis, which produces a high purity product bis(2-hydroxyethyl) terephthalate (BHET), in 83.75% of yield. The product is condensed with diethyl adipate to produce Poly (ethyleneadipate-co-terephthalate) (PEAT). The relationships between the structural, thermal, mechanical, and degradation properties of PEAT with different intrinsic viscosities and composition ratios are studied. The addition of benzene ring improves the thermal properties and tensile strength of PEAT, but also makes them stiffer and less degradable. An increase in intrinsic viscosity can improve the thermal and mechanical properties to some extent but has little effect on the degradation. In general, the PEAT produced by the above process has good thermal properties, controllable degradation properties, and better mechanical properties than Poly (butyleneadipate-co-terephthalate) (PBAT). This work achieves the conversion of waste PET to high value-added PEAT and has potential development prospects in recycling of PET. High purity BHET monomer is obtained by efficient glycolysis of PET using DES as catalyst. The monomer is copolymerized with degradable aliphatic components to prepare a new degradable copolyester PEAT, which has good mechanical properties and certain degradation properties, and is of great significance for the low-carbon and high-value utilization of PET.image