Mechanochemically catalytic upcycling of PET wastes toward aerogels for thermal insulation

Nowadays, a huge amount of polyethylene terephthalate (PET) waste is mainly disposed of through conventional landfills or incineration, leading to significant environmental issues and wastage of petroleum-based resources. These problems have spawned considerable attention to the efficient upcycling of PET waste. Herein, we develop for the first time the depolymerization of PET waste into PET oligomers with controllable molecular weight and narrow polydispersity index through an efficient mechanochemical catalytic approach. The obtained PET oligomers and three additives including carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose (HPMC), and polyvinyl alcohol (PVA), were ground together in a ball mill to construct two-component aerogels: PET/CMC, PET/PVA, and PET/HPMC, which exhibit excellent thermal insulation performance, and the thermal conductivity is as low as 0.0433 W m−1 K−1. Furthermore, melamine was introduced into the two-component aerogels above to build three-component aerogels, which showed a lower thermal conductivity as 0.0401 W m−1 K−1, the improved flame retardancy and compressive resistance. This study offers a new insight into the upcycling of PET waste into novel aerogels with outstanding thermal insulation.