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Benzene Tetraamide: A Covalent Supramolecular Dual Motif in Dynamic Covalent Polymer Networks
Huiyi Zhang1, Annemiek van Hertrooij1, Tobias Schnitzer1
1Institute for Complex Molecular Systems & Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering & Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
Macromolecules
|August 28, 2023
Summary
1,2,4,5-benzene tetraamide (B4A) units create robust dynamic polyamide networks by acting as both cross-linkers and stacking motifs. These supramolecular networks exhibit significantly enhanced mechanical properties and unique relaxation dynamics compared to non-stacking materials.
Area of Science:
- Polymer Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Dynamic covalent chemistry enables self-healing and stimuli-responsive materials.
- Supramolecular interactions, like hydrogen bonding and pi-stacking, can reinforce polymer networks.
- Integrating dynamic covalent and supramolecular features offers a pathway to advanced material properties.
Purpose of the Study:
- To investigate the dual role of 1,2,4,5-benzene tetraamide (B4A) as a cross-linker and supramolecular motif in dynamic polyamide networks.
- To compare the network dynamics and mechanical properties of B4A-containing polyamides with reference materials lacking stacking interactions.
- To elucidate the cooperative contribution of covalent cross-linking and supramolecular stacking to network behavior.
Main Methods:
- Synthesis of dynamic polyamide networks with and without the B4A motif.
- Mechanical testing to determine rubbery plateau modulus and stress relaxation.
- Wide-angle X-ray scattering (WAXS) and variable-temperature infrared spectroscopy (VTIR) to probe network structure and dynamics.
Main Results:
- B4A-based networks exhibited a rubbery plateau modulus approximately 20 times higher than reference networks.
- Branched polyamides with B4A formed strong, reversible supramolecular networks, while reference materials were viscous liquids.
- WAXS and VTIR confirmed cooperative effects of covalent cross-linking and B4A stacking on network dynamics.
- Stress relaxation in B4A networks showed additional modes attributed to stacking dynamics, distinct from covalent chemistry.
Conclusions:
- The 1,2,4,5-benzene tetraamide (B4A) motif effectively enhances polyamide network properties through simultaneous covalent cross-linking and supramolecular stacking.
- Cooperative dynamics between covalent and supramolecular interactions lead to superior mechanical strength and unique relaxation behaviors.
- This study demonstrates a powerful strategy for designing advanced dynamic materials by integrating orthogonal molecular interactions.
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