Melanin-coating as a versatile entry to functionalized cellulose aerogels: synthesis, structure, properties.

A two-step approach consisting of the NaClO/TEMPO mediated oxidation of cellulose, followed by a freeze-drying procedure, led to the production of white carboxylated cellulose nanofibre (CNF) aerogels (a) [1]. By means of an ad hoc protocol, involving alkali-induced oxidative polymerization of 5,6-dihydroxyindole (DHI) [2] on the CNF aerogel, the efficient deposition of melanin polymer onto the aerogel leading to a black coating (b) could be achieved. Preliminary characterization of the melanized aerogels (Mel-CNF) by SEM microscopy confirmed the high degree of porosity of the original aerogel with no apparent bulk polymerization (c). Possible applications of the newly developed Mel-CNF material will be discussed based on a systematic characterization of its adsorption, paramagnetic and free-radical scavenging properties.