Dynamic metallopolymers – A rheology study
Milena Jäger,[a,b] Stefan Zechel,[a,b] Martin D. Hager,[a,b,c] Ulrich S. Schubert[a,b,c]
[a] M. Jäger, S.Zechel, M. D. Hager, U. S. Schubert
Laboratory of Organic and Macromolecular Chemistry (IOMC)
Friedrich Schiller University Jena
Humboldtstr. 10, Jena 07743, Germany
[b] M. Jäger, S.Zechel, M. D. Hager, U. S. Schubert
Jena Center for Soft Matter (JCSM)
Friedrich Schiller University Jena
Philosophenweg 7, Jena 07743, Germany
[c] M. D. Hager, U. S. Schubert
Helmholtz-Institute for Polymers in Energy Applications Jena (HIPOLE Jena)
Lessingstr. 12-14, Jena 07443, Germany
Metallopolymers combine the advantages of “classical” organic polymers, such as lightweight, tunability, and cost-effectiveness1 with the unique properties of metal complexes, including catalytic activity, bioactivity, and conductivity.2,3 This synergy makes them promising materials for different applications, such as self-healing polymers, shape memory polymers, and smart materials.4,5 However, a key challenge lies in understanding their structural dynamics.
In this study, we investigate terpyridine-based metallopolymers complexed with iron(II) or zinc(II) ions to gain deeper insights into their dynamic behavior. These materials were synthesized and characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and elemental analysis (EA). Rheological methods including dynamic mechanical thermal analysis (DMTA), frequency sweeps, stress relaxation, and time-temperature superposition were employed to examine their viscoelastic properties. Additionally, temperature-dependent Raman spectroscopy and density functional theory (DFT) calculations provided insights on the molecular level. Our findings reveal a reversible activation of the metal complexes in zinc(II)-containing metallopolymers, as observed in frequency sweep measurements. Raman spectroscopy confirmed these results, showing morphological changes in the polymer matrix without structural modifications of the metal complex. Furthermore, it was possible to calculate the activation energies for dynamic interactions within the metallopolymers. This study provides a more comprehensive understanding of the dynamic behavior of metallopolymers that could lead to the development of new smart materials with tunable properties.
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(2) Yaul, A. R.; Dhande, V. V.; Pethe, G. B.; Aswar, A. S. Synthesis, Characterization, Biological and Electrical Conductivity Studies of Some Schiff Base Metal Complexes. Bull. Chem. Soc. Ethiop. 2014, 28 (2), 255–264. https://doi.org/10.4314/bcse.v28i2.9.
(3) Ma, D.-L.; He, H.-Z.; Leung, K.-H.; Chan, D. S.-H.; Leung, C.-H. Bioactive Luminescent Transition-Metal Complexes for Biomedical Applications. Angew. Chem. Int. Ed. 2013, 52 (30), 7666–7682. https://doi.org/10.1002/anie.201208414.
(4) Bode, S.; K. Bose, R.; Matthes, S.; Ehrhardt, M.; Seifert, A.; H. Schacher, F.; M. Paulus, R.; Stumpf, S.; Sandmann, B.; Vitz, J.; Winter, A.; Hoeppener, S.; J. Garcia, S.; Spange, S.; Zwaag, S. van der; D. Hager, M.; S. Schubert, U. Self-Healing Metallopolymers Based on Cadmium Bis(Terpyridine) Complex Containing Polymer Networks. Polym. Chem. 2013, 4 (18), 4966–4973. https://doi.org/10.1039/C3PY00288H.
(5) Meurer, J.; Hniopek, J.; Bätz, T.; Zechel, S.; Enke, M.; Vitz, J.; Schmitt, M.; Popp, J.; Hager, M. D.; Schubert, U. S. Shape-Memory Metallopolymers Based on Two Orthogonal Metal–Ligand Interactions. Adv. Mater. 2021, 33 (7), 2006655. https://doi.org/10.1002/adma.202006655.