Environmentally sensitive hydrogel functionalized with electroactive and complexing-iron(III) catechol groups

Thermoresponsive pNIPA (poly (N-isopropylacryla-mide)) gels modified with dopamine methacrylamide were syn-thesized using free-radical polymerization. In this way, thecatechol groups were introduced into the polymer network. Thepresence of dopamine in the gel led to a significant shift in thevolume phase transition temperature (VPTT). It was found thathydrogels were electroactive and that oxidation of catecholgroups also led to a strong shift in the VPTT. The temperaturewindow, that is, the range of temperature where volume of thegel could be substantially changed by oxidation of the catecholgroups, for the gel formed from the polymerization solution con-taining 5% of the dopamine derivative, was 30–408C. Addition-ally, the influence of Fe31ions, which form the most stablecomplexes with dopamine, on swelling behavior of the gels wasinvestigated at various pH.