Circular Polydiketoenamine Elastomers with Exceptional Creep Resistance via Multivalent Cross-Linker Design

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Elastomers are vital in textiles, foam, and rubber but face recycling challenges due to difficult polymer chain deconstruction.
• Incorporating reversible bonds can enhance elastomer circularity, but often leads to undesirable creep.
• Dynamic covalent chemistry offers a pathway to create recyclable and stable polymer networks.

Purpose of the Study:

• To design and synthesize dynamic covalent polydiketoenamine (PDK) elastomers with both high recyclability and excellent creep resistance.
• To investigate the role of cross-linking architecture in controlling elastomer properties.
• To understand the mechanism of PDK bond deconstruction for efficient monomer recovery.

Main Methods:

• Synthesis of polydiketoenamine (PDK) elastomers using polyetheramine and triketone monomers.
• Architecting dynamic covalent networks by appending polytopic cross-linking functionality.
• Mechanical testing of elastomers and carbon-reinforced rubbers, including creep tests at high temperatures.
• Analysis of PDK deconstruction using acidolysis and computational mapping of reaction pathways.

Main Results:

• Polytopic cross-linking significantly reduced creep in PDK elastomers from over 200% to less than 1% compared to monotopic controls.
• The synthesized elastomers exhibited mechanical robustness and stability, even at elevated temperatures.
• Materials were readily depolymerized to pure monomers in high yield, demonstrating efficient circularity.
• Multivalent chain ends were found to be crucial for complete PDK deconstruction.

Conclusions:

• Dynamic covalent polydiketoenamine (PDK) elastomers can be engineered for both efficient recycling and high-temperature creep resistance.
• Polytopic cross-linking is key to achieving mechanical stability and preventing creep in these dynamic materials.
• The developed materials represent a significant advancement in creating sustainable and high-performance elastomers.