Benzene Tetraamide: A Covalent Supramolecular Dual Motif in Dynamic Covalent Polymer Networks

Huiyi Zhang; Annemiek van Hertrooij; Tobias Schnitzer; Yinjun Chen; Soumabrata Majumdar; Rolf A T M van Benthem; Rint P Sijbesma; Johan P A Heuts

doi:10.1021/acs.macromol.3c01083

Benzene Tetraamide: A Covalent Supramolecular Dual Motif in Dynamic Covalent Polymer Networks

Macromolecules. 2023 Aug 11;56(16):6452-6460. doi: 10.1021/acs.macromol.3c01083. eCollection 2023 Aug 22.

Authors

Huiyi Zhang¹, Annemiek van Hertrooij¹, Tobias Schnitzer¹, Yinjun Chen¹, Soumabrata Majumdar¹, Rolf A T M van Benthem^{2

3}, Rint P Sijbesma¹, Johan P A Heuts¹

Affiliations

¹ Institute 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.
² Laboratory of Physical Chemistry, Department of Chemical Engineering & Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
³ PTX-C, Shell Technology Center Amsterdam, Grasweg 31, 1031 HW Amsterdam,The Netherlands.

Abstract

In dynamic polyamide networks, 1,2,4,5-benzene tetraamide (B4A) units act simultaneously as a dynamic covalent cross-linker and as supramolecular stacking motif. This results in materials with a rubbery plateau modulus that is about 20 times higher than that of a corresponding reference network in which the supramolecular interaction is suppressed. In branched polyamides with the same B4A dynamic motif, hydrogen bonding and stacking lead to strong and reversible supramolecular networks, whereas a branched polyamide with the nonstacking reference linker is a viscous liquid under the same conditions. Wide-angle X-ray scattering and variable-temperature infrared experiments confirm that covalent cross-linking and stacking cooperatively contribute to the dynamics of the network. Stress relaxation in the reference network is dominated by a single mode related to the dynamic covalent chemistry, whereas relaxation in the B4A network has additional modes assigned to the stacking dynamics.