Polydimethylsiloxane-Assisted Catalytic Printing for Highly Conductive, Adhesive, and Precise Metal Patterns Enabled...

Paper and textile are two ideal carriers in wearable and printed electronics because of their flexibility and low price. However, the porous and fibrous structures restrain their use in printed electronics because the capillary effect results in ink diffusion. Especially, conventional metal ink needs to be post-treated at high temperatures (>150 °C), which is not compatible with paper and textile. To address problems involved in ink diffusion and avoid high-temperature treatment, herein, a new strategy is proposed: screen-printing of high-viscosity catalytic inks combined with electroless deposition of metal layers on paper and textile substrates. The ink consists of Ag nanoparticles, a polydimethylsiloxane (PDMS) prepolymer, and a curing agent. PDMS as a viscoelastic matrix of catalysts plays key roles in limiting ink diffusion, enhancing interfacial adhesion between the substrate and metal layer, keeping metal flexible. As a demonstration, metal Cu and Ni are printed, respectively. The printed precision (diffusion < 1% on filter paper) can be controlled by adjusting the Ag content in the PDMS matrix; interfacial adhesion can be enhanced by ink coating on substrate microfibers and metal embedding into the PDMS matrix. In addition, Cu on paper shows extremely low sheet resistance (0.29 mΩ/□), and Cu on nylon shows outstanding foldability with a resistance of less than five times of initial resistance during 5000 folding cycles.