Dynamic decrosslinking enables self-healing, reprocessability, and upcycling in polyurethane networks.

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Engineering

Background:

• Thermosetting polymers offer excellent mechanical properties but pose environmental challenges due to their non-reprocessable nature.
• Current recycling methods for thermosets are limited, often resulting in performance degradation after multiple cycles.
• Developing sustainable solutions for thermoset waste is crucial for environmental protection and resource conservation.

Purpose of the Study:

• To introduce a new strategy for the decrosslinking and upcycling of post-service thermosets.
• To demonstrate the transformation of thermosets into reprocessable thermoplastics.
• To showcase the high-value applications of the upcycled materials.

Main Methods:

• A dynamic polyurethane network incorporating hindered urea bonds (HUBs) was synthesized.
• Controlled network disassembly was achieved through amine-induced exchange reactions of HUBs.
• The decrosslinked material was used to create advanced composites with glass fiber and carbon nanotubes.

Main Results:

• The dynamic polyurethane network exhibited high mechanical strength, self-healing, and thermal reprocessability.
• Decrosslinking via HUB exchange reactions successfully converted thermosets into reprocessable thermoplastics.
• Upcycled materials significantly enhanced glass fiber matrices (229% toughening) and provided effective electromagnetic shielding (28.1 dB).

Conclusions:

• A molecularly engineered decrosslinking-upcycling approach for thermosets was established.
• This method enables the creation of high-performance composites from recycled thermosetting polymers.
• The findings present a viable pathway for circular thermoset utilization, advancing sustainable polymer technologies.