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Robust Self-Healing Adhesives Based on Dynamic Urethane Exchange Reactions
Lillian M Felsenthal1, Subeen Kim1, William R Dichtel1
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
ACS Applied Materials & Interfaces
|October 15, 2024
Summary
This study developed a dynamic urethane adhesive using covalent adaptable networks (CANs). The adhesive demonstrates self-healing and reusable properties through reversible bonding, expanding CAN applications.
Area of Science:
- Materials Science
- Polymer Chemistry
Background:
- Thermoset polyurethanes (PUs) are typically single-use materials.
- Covalent adaptable networks (CANs) offer reprocessing capabilities through bond exchange.
- Previous CAN applications have not focused on adhesive functionalities.
Purpose of the Study:
- To create a dynamic urethane adhesive utilizing CAN technology.
- To demonstrate reversible covalent bonding between PU CANs and substrates.
- To explore self-healing and reusability in structural adhesives.
Main Methods:
- Synthesis of thermoset PU films with and without a carbamate exchange catalyst (Zr(tmhd)4).
- Characterization using FT-IR spectroscopy and dynamic mechanical thermal analysis (DMTA).
- Evaluation of dynamic bond exchange via stress relaxation analysis and adhesive performance testing.
Main Results:
- The catalyzed PU CAN film exhibited dynamic bond exchange behavior.
- The CAN adhesive demonstrated self-healing properties.
- The adhesive retained strength over five cycles due to reversible covalent bonding to glass.
Conclusions:
- Industrially relevant CANs can be extended to structural adhesive applications.
- Reversible transcarbamoylation with substrates enables adhesive reusability.
- This technology offers a sustainable alternative to single-use PU materials.
