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Abstract Conjugated polymers have received significant attention as potentially lightweight and highly tailorable alternatives to inorganic semiconductors, but their synthesis is often complex, produces toxic byproducts, and they are not typically designed to be degradable or recyclable. These drawbacks necessitate dedicated efforts to discover materials with design motifs that enable targeted and efficient degradation of conjugated polymers. In this vein, the synthetic simplicity of 1,4‐dihydropyrrolo[3,2‐b]pyrroles (DHPPs) is exploited to access azomethine‐containing copolymers via a benign acid‐catalyzed polycondensation protocol. Polymerizations involve reacting a dialdehyde‐functionalized dihydropyrrolopyrrole withp‐phenylenediamine as the comonomer usingp‐toluenesulfonic acid as a catalyst. The inherent dynamic equilibrium of the azomethine bonds subsequently enabled the degradation of the polymers in solution in the presence of acid. Degradation of the polymers is monitored via NMR, UV‐vis absorbance, and fluorescence spectroscopies, and the polymers are shown to be fully degradable. Notably, while absorbance measurements reveal a continued shift to higher energies with extended exposure to acid, fluorescence measurements show a substantial increase in the fluorescence response upon degradation. Results from this study encourage the continued development of environmentally‐conscious polymerizations to attain polymeric materials with useful properties while simultaneously creating polymers with structural handles for end‐of‐life management or/and recyclability.
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Chemically recyclable polymers: a circular economy approach to sustainability
The current practices in the generation and disposal of synthetic polymers are largely unsustainable. As part of the solution, the development of biodegradable polymers, which constitute a class of “green polymers” according to green chemistry principles, has been intensively pursued in the past two decades. However, the degradation of such polymers in Earth's landfills typically leads to no recovery of the materials’ value, and their degradation in the Oceans could create new or unintended environmental consequences. Industrial mechanical recycling always suffers from a significant quality loss. The proposed more sustainable solution is to develop chemically recyclable polymers that not only solve the end-of-life issue of polymers, but also provide a direct approach to establish a circular materials economy. Accordingly, this critical review article captures some selected highlights of the emerging area of recyclable “green polymers” by focusing on the major progress made and the technical and environmental benefits obtained in the development of repurposing and depolymerization processes for chemical recycling of polymers at the end of their useful life.
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- Award ID(s):
- 1664915
- PAR ID:
- 10066487
- Date Published:
- Journal Name:
- Green Chemistry
- Volume:
- 19
- Issue:
- 16
- ISSN:
- 1463-9262
- Page Range / eLocation ID:
- 3692 to 3706
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c7gc01496a
