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Reprocessable, Self-Healing, and Creep-Resistant Covalent Adaptable Network Made from Chain-Growth Monomers with
Tong Wang1, Yixuan Chen1, Boran Chen1
1Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208 United States.
ACS Macro Letters
|August 16, 2024
Summary
New covalent adaptable networks (CANs) utilize nonisocyanate thiourethane chemistry for enhanced reprocessability and self-healing. These dynamic materials demonstrate associative dynamics, with stress relaxation governed by polymer backbone relaxation.
Area of Science:
- Polymer Chemistry
- Materials Science
- Organic Chemistry
Background:
- Covalent adaptable networks (CANs) offer dynamic properties for advanced materials.
- Nonisocyanate thiourethane chemistry provides a pathway for synthesizing novel CANs.
- Understanding the relationship between network dynamics and material properties is crucial for design.
Purpose of the Study:
- To synthesize and characterize novel CANs using nonisocyanate thiourethane chemistry.
- To investigate the reprocessability, self-healing, and creep resistance of these CANs.
- To explore the relationship between network dynamics and stress relaxation behavior.
Main Methods:
- Synthesis of glycidyl methacrylate with cyclic dithiocarbonate (GMA-DTC).
- Free-radical polymerization of n-hexyl methacrylate with GMA-DTC.
- Cross-linking with difunctional amine and characterization via stress relaxation and tensile property recovery.
Main Results:
- Successfully synthesized CANs with dynamic thionourethane and disulfide bonds.
- Demonstrated CAN reprocessability with full recovery of cross-link density.
- Exhibited complete self-healing at 110 °C and excellent creep resistance at 90-100 °C.
Conclusions:
- The dynamic covalent bonds enable excellent material recyclability and repair.
- Associative character dominates the dynamic response of the CANs.
- The activation energy of stress relaxation is dictated by the polymer backbone's α-relaxation, supporting the hypothesis for associative CANs.
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