Histidine–Zinc Interactions Investigated by Isothermal Titration Calorimetry (ITC) and their Application in Self-Healing Polymers

Enke, Marcel; Jehle, Franziska; Zechel, Stefan; Vitz, Jürgen; Hager, Martin D.; Schubert, Ulrich S.

Abstract:

Histidine–zinc interactions are believed to play a key role in the self-healing behavior of mussel byssal threads due to their reversible character. Taking this as inspiration, the authors synthe- size here histidine-rich copolymers, as well as model histidine compounds and characterize them using isothermal titration calorimetry (ITC). With this approach, the influence of two dif- ferent zinc(II) salts and the role in the complex formation of the amine function of the imida- zole ring are investigated in detail. The extracted metal–ligand ratios are utilized to design novel self-healing metallopoly- mers. For this purpose, n-lauryl methacrylate is copolymerized with the histidine monomer via reversible addition-fragmen- tation chain transfer polymerization. The copolymers are crosslinked using different zinc salts, and the resulting coat- ings are characterized with Raman spectroscopy to investi- gate the metal coordination behavior and with scratch healing tests to investigate the self-healing capacity. Finally, the self- healing behavior of the different materials is correlated with the metal–ligand binding affinity measured by ITC.

Research areas:

• Polymer Science

Year:

2017

Type of Publication:

Article

Journal:

Macromolecular Chemistry and Physics

Volume:

218

Number:

1600458

DOI:

10.1002/macp.201600458