Impact of Metal Coordination on the Structures and Dynamics of Ethyl Acrylate-Vinylimidazole Copolymers.

Abstract

The integration of weak sacrificial bonds into the polymer networks has become a universal approach for enhancing the mechanical properties of polymers. Particularly, the presence of non-covalent associative interactions leads to significant changes in polymer dynamics and viscoelastic behaviors. In this study, we report a high-performance metallo-supramolecular elastomer based on metal-imidazole coordination. Different metal ions, including Cu²⁺, Co²⁺, and Zn²⁺, were incorporated into a random copolymer composed of ethyl acrylate (EA) and 1-vinylimidazole (VI), resulting in dramatic variation in mechanical and viscoelastic properties due to differences in metal-coordination strength. High-resolution 2D ¹H double-quantum/single-quantum (DQ/SQ) NMR spectroscopy directly reveals the formation of metal-coordination in the polymer materials and shows that metal-coordination leads to enhanced structural and dynamic heterogeneity. Specifically, both local segmental motions and terminal relaxation of metallo-supramolecular elastomer are slowed down by the metal-coordination. This study provides detailed molecular-level insights into the structure and dynamics of polymer networks with varying metal-coordination strengths, providing great potential for the rational design of high-performance metallo-supramolecular polymers.