Mechanically Robust and Recyclable Polyurea Networks Enabled by Dynamic Caprolactam-Urea Bonds

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Dynamic covalent bonds offer pathways to advanced, recyclable polymer materials.
• Developing sustainable polymers with robust mechanical and chemical properties is crucial for circular economy initiatives.

Purpose of the Study:

• To report a novel catalyst-free dynamic caprolactam-urea (CAU) bond for constructing recyclable polymer networks.
• To demonstrate the dual mechanical and chemical recyclability of poly(caprolactam-ureas) (PCAU) networks.
• To establish CAU chemistry as a platform for high-performance dynamic polymers in circular manufacturing.

Main Methods:

• Synthesis of poly(caprolactam-ureas) (PCAU) networks utilizing a catalyst-free dynamic caprolactam-urea (CAU) bond.
• Evaluation of mechanical robustness, solvent resistance, and hydrolytic stability of PCAU networks.
• Mechanical recycling via hot-pressing and chemical recycling through catalyst-free depolymerization and repolymerization.

Main Results:

• PCAU networks exhibit remarkable mechanical robustness, solvent resistance, and hydrolytic stability.
• Mechanical recycling via hot-pressing over multiple cycles retained >92% of mechanical properties.
• Catalyst-free chemical recycling achieved selective depolymerization into caprolactam monomers, enabling repolymerization into new PCAU networks.

Conclusions:

• The developed CAU chemistry provides a versatile platform for designing high-performance dynamic polymers.
• PCAU networks demonstrate excellent dual mechanical and chemical recyclability, supporting sustainable material applications.
• This approach facilitates circular manufacturing through efficient monomer recovery and repolymerization.