One-Pot Upcycling of Heterogeneous Polyester Waste to Biodegradable Thermoplastics: A Cost-Effective Solution for a Circular Economy

Abstract

The efficient recycling of poly(ethylene terephthalate) and poly(butylene terephthalate), the most extensively produced plastics, is essential for reducing global carbon emissions and the current dependence on fossil resources. However, the chemical recycling of polyesters primarily involves polymer-to-monomer and monomer-to-polymer processes, resulting in significant greenhouse gas emissions owing to significant electricity and fuel consumption. Herein, this research reports a simple and efficient one-pot polymer-to-polymer upcycling process that directly converts these two polyester wastes into biodegradable thermoplastic poly(ether ester)s using poly(tetramethylene ether) glycol (PTMG). The synthesized series of poly((ET-co-BT)-mb-PTMG) (PEBTG) exhibit a maximum tensile strength of 68 MPa, with 85% weight loss after 20 weeks in composted soil. Techno-economic analysis and life cycle assessment indicate that PEBTG is more cost-competitive and environmentally beneficial than currently existing plastics derived from fossil fuels, such as polypropylene and polybutylene adipate terephthalate. Once de-risked, the proposed upcycling strategy for polymer waste can be extended to expedite the development of a sustainable plastic economy.