Minimal N-hydroxyphthalimide-urethane bonds enable superior thermomechanical stability for covalent adaptable
Yuhan Yin1,2, Shijia Yang1,2, Yong Zhou3
1Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
Nature Communications
|March 3, 2026
Summary
This study introduces a novel strategy for covalent adaptable networks (CANs) using dynamic N-hydroxyphthalimide-urethane bonds (NUBs). This approach enhances reprocessability and mechanical stability without compromising performance.
Area of Science:
- Materials Science
- Polymer Chemistry
- Chemical Engineering
Background:
- Classic thermosets lack reprocessability, a key limitation.
- Covalent adaptable networks (CANs) offer reprocessability but often sacrifice mechanical properties and thermal stability.
- Dynamic covalent bonds (DCBs) are crucial for CANs' adaptability.
Purpose of the Study:
- To develop a "High Activity & Low Content" strategy for CANs.
- To achieve superior thermomechanical stability and reprocessability in CANs.
- To overcome the trade-off between mechanical performance and reprocessability in dynamic polymers.
Main Methods:
- Utilized dynamic N-hydroxyphthalimide-urethane bonds (NUBs) for CANs.
- Employed a catalyst-free addition reaction between N-hydroxyphthalimides and isocyanates.
- Incorporated a low content (5 mol%) of dynamic units to create poly(N-hydroxyphthalimide-urethanes) (PNU) networks.
Main Results:
- Achieved near-quantitative conversion in 2 hours at room temperature.
- Demonstrated bond dissociation up to ~28% at 120°C.
- Developed PNU networks with superior mechanical properties, crack tolerance, and high-temperature stability.
- Exhibited excellent reprocessability and mild degradability in neutral aqueous conditions with minimal DCB content.
Conclusions:
- The "High Activity & Low Content" strategy effectively balances reprocessability and thermomechanical robustness in CANs.
- NUBs enable efficient dynamic characteristics with reduced DCB content.
- This approach overcomes the traditional limitations of dynamic polymers, offering enhanced performance and sustainability.
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