A modular telechelic catechol platform for tunable Fe- and V-coordinated dynamic polymer gels

Abstract

Dynamic metal–catechol coordination networks provide a powerful platform for bioinspired polymer gels, yet systematic molecular design rules connecting monomer structure to network mechanics and thermal behavior remain limited. Here, a modular series of telechelic catechol-based monomers were synthesized with controlled ethylene glycol spacer lengths and either ester or amide linkages and rapidly cross-linked with FeCl₃ or VCl₃ under mild NH₃-mediated basic conditions. By varying the linker length, functional group identity, and metal ion, we establish clear structure–property relationships across a family of reticulated gels with tunable thermal stability, glass transition behavior, and viscoelastic response. Spectroscopic analysis (ATR-FTIR, resonance Raman, EPR, and Mössbauer) reveals distinct coordination environments, including oxidation to V(iv) species that yield more elastically resilient, kinetically stabilized networks relative to stiffer but more brittle Fe-based gels. Finally, the coordination cross-links can be selectively disrupted under mild conditions to recover the original catechol monomers, demonstrating a chemically reversible pathway toward closed-loop gel design. Together, these results provide a systematic framework for engineering dynamic catechol-based polymer networks with tailored properties through molecular-level control.