Soft dynamic covalent hydrogels based on iron(III)tetraphenylporphyrinato-functionalized 4-arm poly(ethylene oxide)

New hydrogels were prepared from iron(III)tetraphenylporphyrinato-functionalized 4-arm poly(ethylene oxide) films in which water plays both the role of a cross-linker and a swelling agent. Depending on the pH conditions, the hydrogels present the feature of either a chemical network or that of a dynamic transient network. Importantly, this intriguing behaviour is fully reversible as evidenced by rheological analysis and solubility tests.