Matter
Volume 4, Issue 4, 7 April 2021, Pages 1352-1364
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Article
Dual closed-loop chemical recycling of synthetic polymers by intrinsically reconfigurable poly(disulfides)

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Highlights

  • Synthetic poly(disulfides) polymers can be chemically recycled in a closed loop

  • The depolymerization process is efficiently completed in basic aqueous solutions

  • The chemically recycled materials are additive substitutable and modulus tunable

Progress and potential

It is crucial to develop polymeric materials that can be recycled repeatedly. Here, we show that the intrinsic reconfigurability of poly(thioctic acid) enables the establishment of a closed-loop chemical recycling system among single monomer and two types of polymeric materials. By elaborating the reversible ring-opening polymerization of thioctic acid, both the preparation (polymerization) and recycling (depolymerization) process of this material can be performed in a simple, mild, environmentally friendly, and high-yield manner. The structure and properties of the resulting materials can be easily tuned by the nature of metal ion additives, either exhibiting amorphousness with excellent stretchability and self-healing ability or showing semi-crystallinity with mechanical robustness. This unique polymer combining simplicity of preparation, functional complexity, and chemical recyclability shows great potential in constructing future circular plastic systems.

Summary

The excessive use of plastics has led to severe global problems involving environmental, energy, and health issues and demands for sustainable and recyclable alternatives. Toward circular plastics, the development of efficient chemical recycling methods without loss of properties or allowing reprocessing into new materials offer tremendous opportunities. Here, we report an intrinsically recyclable and reconfigurable poly(disulfide) polymer using a natural small molecule, thioctic acid (TA), as the feedstock. Taking advantage of its dynamic covalent ring-opening polymerization, this material enables a dual closed-loop chemical recycling network among TA monomers and two kinds of polymer products, including self-healing elastomers and mechanically robust ionic films. Mild and complete depolymerization into monomers in diluted alkaline aqueous solution is achieved with yields of recovered monomers up to 86%. The polymer materials can be repeatedly recycled and reused with reconfigurable polymer composition and tunable mechanical properties offering prospects for sustainable functional plastics.

Keywords

sustainable plastics
chemical recycling
dynamic polymers
dynamic covalent chemistry

Material Advancement Progression

MAP4: Demonstrate

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