Self-Reducing Silver Ink on Polyurethane Elastomers for the Manufacture of Thin and Highly Stretchable Electrical Circuits
Krzysztof K. Krawczyk, Jonas Groten, Oleksandr Glushko, Matic Krivec, Matthias Frühwirth, Gernot Schulz, Christian Wolf, Delara Hartmann, Maximilian Moser, Megan J. Cordill, Barbara Stadlober, and Thomas Griesser
Chemistry of Materials 2021 33 (8), 2742-2755, 3/2021
Stretchable conductive films were obtained by screen printing and thermal treatment of a homogenous ink comprising a thermally reducible silver formate complex, an acrylate monomer, and a radical initiator. In the curing process, both the filler nanoparticles and the polymer matrix are generated in situ, at temperatures as low as 100 °C. The obtained conductors, consisting of percolated silver nanoparticles embedded in a polymeric matrix, typically show a resistivity of (2–4) × 10–5 Ω·m. When applied on an elastomeric substrate, the composite is stretchable up to 200% with very low R/R0 values, which is unprecedented for stretchable silver composite inks. Quasi-in situ confocal laser scanning microscopy of the strained samples revealed an initial fracture strain above 40%, which is unusually high for metal–nanoparticle films. The described system was compared to some commercial stretchable screen-printing inks and proved superior with regard to both R/R0 and resistance to cyclic tensile loading.