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

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Plastic waste, particularly polyethylene terephthalate (PET), poses significant environmental challenges.
• Conventional recycling methods often lead to degradation of polymer properties.
• UV exposure causes photodegradation in polymers, reducing their performance and lifespan.

Purpose of the Study:

• To develop a novel in situ chemical upcycling strategy for PET plastic waste.
• To enhance the UV resistance and mechanical properties of PET through a dual photo-response monomer.
• To provide a sustainable solution for plastic recycling that improves material performance.

Main Methods:

• A customized diphenylacetylene monomer with dual photo-response was synthesized.
• The monomer was in situ inserted into the polyethylene terephthalate (PET) macromolecular chain via one-pot transesterification (slight-depolymerization and re-polymerization).
• The upcycled PET was exposed to UV radiation to induce photo-crosslinking and evaluate property changes.

Main Results:

• Diphenylacetylene groups absorbed high-energy UV rays and emitted harmless fluorescence.
• UV-induced photo-crosslinking formed extended π-conjugated structures, red-shifting the UV absorption band.
• Upcycled PET exhibited enhanced UV resistance and superior mechanical strength with increased UV exposure time, counteracting photodegradation.

Conclusions:

• The proposed in situ chemical upcycling strategy effectively enhances PET properties.
• This oligomer-scale upcycling method offers a new approach to plastic recycling, improving material durability.
• The strategy addresses the issue of performance degradation in polymers during use and recycling.