Circularly Recyclable Polymers Featuring Topochemically Weakened Carbon-Carbon Bonds

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Current plastic recycling methods face challenges due to energy-intensive processes and poor selectivity in breaking carbon-carbon bonds.
• Achieving closed-loop circular utilization of plastics is crucial for environmental sustainability but hindered by the stability of conventional polymer structures.

Purpose of the Study:

• To develop a novel topochemical approach for modifying polymer structures to facilitate efficient and selective depolymerization.
• To introduce elongated carbon-carbon bonds in various polymers to lower dissociation energies and enable easier recycling.

Main Methods:

• A topochemical strategy was employed to create elongated carbon-carbon bonds (1.57–1.63 Å) in the solid state for 12 different polymers across three classes.
• The synthesized polymers were characterized for their thermal stability, depolymerization behavior, processability, and mechanical properties.

Main Results:

• The modified polymers demonstrated rapid depolymerization via the elongated bond breakage within a 140–260 °C temperature range.
• These materials remained stable under harsh conditions, were processable, and 3D-printable, exhibiting high depolymerization yields and tunable mechanical properties.
• The approach successfully modified 12 distinct polymers, showcasing broad applicability.

Conclusions:

• The topochemical synthesis of polymers with elongated carbon-carbon bonds offers a promising route for efficient and selective plastic recycling and upcycling.
• This method, utilizing simple photochemistry without expensive catalysts, enables complete materials circularity and practical applications.
• The developed polymers present a sustainable alternative for materials with tunable properties and enhanced recyclability.