Dual Photo-Responsive Diphenylacetylene Enables PET In-Situ Upcycling with Reverse Enhanced UV-Resistance and Strength

A novel in situ chemical upcycling strategy for plastic waste is proposed by the customized diphenylacetylene monomer with dual photo-response. That is, diphenylacetylene reactive monomers are in situ inserted into the macromolecular chain of polyethylene terephthalate (PET) plastics/fibers through one-pot transesterification of slight-depolymerization and re-polymerization. On the one hand, the diphenylacetylene group absorbs short-wave high-energy UV rays and then releases long-wave low-energy harmless fluorescence. On the other hand, the UV-induced photo-crosslinking reaction among diphenylacetylene groups produces extended pi-conjugated structure, resulting in a red-shift (due to decreased HOMO-LUMO separation) in the UV absorption band and locked crosslink points between PET chains. Therefore, with increasing UV exposure time, the upcycled PET plastics exhibit reverse enhanced UV resistance and mechanical strength (superior to original performance), instead of serious UV-photodegradation and damaged performance. This upcycling strategy at oligomer-scale not only provides a new idea for traditional plastic recycling, but also solves the common problem of gradual degradation of polymer performance during use. Starting from the oligomer-scale, this work implements a novel in situ chemical upcycling strategy for PET plastic wastes through tailored diphenylacetylene monomer. Uniquely, the dual photo-responses of diphenylacetylene enable upcycled PET plastics with reverse enhanced UV-resistance and strength.image

Automated summary

This study proposes a novel in situ chemical upcycling strategy for plastic waste using a customized diphenylacetylene monomer. By inserting diphenylacetylene reactive monomers into the macromolecular chain of polyethylene terephthalate (PET) plastics/fibers, the upcycled PET plastics exhibit reverse enhanced UV resistance and mechanical strength.