Degradation and Synthesis of Poly (Ethylene Terephthalate) by Functionalized Ionic Liquids

As a green environmentally friendly solvent and catalyst, ionic liquids have attracted much attention because of their various properties, such as good solubility, high catalytic activity, good thermal stability and easy recycling. Polyesters have tremendous production capacity around the world with applications in wide ranges, and at the same time their wastes result in some negative effects on environment. This paper is aimed to review commonly chemical degradation and recycling methods of polyester waste, and also the development in synthesis of polyester catalyzed by ionic liquids. Polyester can be easily converted into its monomers or oligomers by the method of chemical recycling for the purpose of recycling use. Several methods of chemical degradation of polyester waste locally and abroad are summarized, including hydrolysis method, methanol depolymerization method, ethanol depolymerization method, and ethylene glycol depolymerization method. The advantages and disadvantages of main chemical depolymerization methods are compared. Recent studies especially focus on degradation recycling of the most common polyester-poly (ethylene terephthalate) (PET), using functionalized ionic liquids as catalyst. Other applications of functionalized ionic liquids catalyst in polymerization of PET and mechanism of the glycolysis of PET catalyzed by Lewis acidic ionic liquids are also introduced. At last, challenges in the synthesis and degradation of polyester catalyzed by Lewis acidic ionic liquids are overviewed.