Installing a Trigger to Upcycle High-Density Polyethylene.

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Polyethylene (PE) lacks inherent degradation sites, hindering sustainable recycling.
• Introducing C═C bonds into PE offers a strategy for controlled degradation and upcycling.
• Existing methods for C═C bond incorporation face challenges in controlling copolymer composition and regularity.

Purpose of the Study:

• To develop a controlled method for incorporating C═C bonds into PE via copolymerization.
• To investigate the properties and degradation behavior of the resulting ethylene/butadiene (E/BD) copolymer.
• To demonstrate the upcycling potential of the degradation products.

Main Methods:

• Utilized an amidinate gadolinium complex for ethylene and butadiene (E/BD) copolymerization.
• Characterized the copolymer's properties, comparing them to commercial high-density-PE.
• Investigated the degradation of the copolymer into α,ω-telechelic oligomers.
• Demonstrated upcycling of oligomers into compatibilizers via atom-transfer radical polymerization and immortal ring-opening polymerization.

Main Results:

• Achieved controllable E/BD copolymerization with butadiene incorporated in a uniform 1,4 mode.
• The resulting copolymer exhibited comparable physical, mechanical, processing, and antioxygen properties to commercial high-density-PE.
• The incorporated C═C bonds facilitated controlled degradation into narrow-distribution α,ω-telechelic oligomers.
• Successfully upcycled these oligomers into functional compatibilizers.

Conclusions:

• Amidinate gadolinium complex enables controlled E/BD copolymerization for PE functionalization.
• The functionalized PE maintains desirable properties while allowing for controlled degradation.
• This approach provides a viable route for the sustainable upcycling of polyolefins into valuable materials.