Eumelanin & keratin sourced from waste: unraveling criss-cross functionalities for green electronic applications

In the framework of the Circular Economy this study provides a detailed analysis of water-based suspensions of two biopolymers derived by sustainable processes: eumelanin from insect farming and keratin from chicken feathers. The latter material was obtained via two different extraction procedures. Colloidal-like suspensions were produced in water either as a single component system or a mixture of both in selected ratios, taking advantage of their high solubility. The suspensions were examined using a comprehensive set of chemical, structural and dielectric techniques to gather information on their properties. Small-Angle x-ray Scattering results provided insights into the elemental polymer sections within the suspension, while Transmission Electron Microscopy images indicate that keratin is the component driving the shape of the aggregation structure in a colloidal environment, and, in some cases, eumelanin internalization. Furthermore, the co-presence of both polymers in water determines the aggregation dimensions and shapes. The discussion focuses on the influence of the aggregation on the dielectric proper-ties by comparing the former to the AC dynamic response returned by Broadband Dielectric Spectroscopy (BDS). Within the BDS framework various items are highlighted including dielectric relaxations, screening effects, counterion condensation and ionic charge transport. The results shown in this work let to foresee the adoption of water or biofriendly aqueous BSF-EuM:Keratin suspensions in the production of devices and sensors with low environmental impact.