Development of recycling strategies using bio-based polymers for the recovery of the conductive inks in flexible printed electronics

Electronic waste (e-waste) has become a growing concern due to the increasing volume of electronic devices resulting from rapid technological advancement and lower manufacturing costs. Several industrial and academic efforts have focused on reducing e-waste through industrially scalable recycling pathways. As part of this effort, this research investigates the use of terpene solvents (i.e. linalool, carvone and terpineol), and albumen, to enable simple recycling strategies for recovering metallic particles from the conductive inks used in flexible printed electronics. Moreover, a sacrificial layer of ethyl cellulose dissolvable in terpenes and a sacrificial layer of albumen degradable in sodium hydroxide were developed. The use of linalool combined with ultrasonication to dissolve commercial inks without a sacrificial layer was explored as an additional recycling strategy. The relevant physicochemical attributes of the developed sacrificial layer formulations and the resulting film properties when blade-coated onto commercial PET were characterized. The printability and functionality of various commercial copper and silver inks on the sacrificial layers were subsequently verified through wireless readout tests of printed antennae. The recyclability of the inks and reusability of both the substrate and solvent/degrading solution were demonstrated by sonicating the printed components, followed by filtration. These results indicate that both the sacrificial layers and the use of linalool are efficient strategies for separating the metallic components of printed electronics and reusing both the substrate and solvent/degrading solution. Furthermore, the adoption of terpenes as green solvents further contributes to the sustainable processing of these electronic devices, offering a promising step towards a circular economy in printed electronics.