Polydimethylsiloxane-Assisted Catalytic Printing for Highly Conductive, Adhesive, and Precise Metal Patterns Enabled on Paper and Textiles

Abstract

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.

Fabricating flexible conductive structures by printing techniques and printable conductive materials

“…There are many factors that affect the screen-printing quality and characteristics for fabricating flexible electronics, such as the viscosity of the ink, printing speed, squeegee angle and geometry, distance between the screen and the substrate, mesh size, and printing materials. 71,72 Notably, the ink exposed to the air induces a quickly dry and a blocked mesh during screen printing, which should be paid attention to fabricate flexible electronics.…”

Printable All-Paper Pressure Sensors with High Sensitivity and Wide Sensing Range

“…However, these organic substrates are difficult to degrade, resulting in electronic pollution. With the rise of green electronics and recycled electronics, cellulose paper has been widely exploited as a flexible substrate because of its naturally biodegradable and biocompatible properties. , Combined with cost-effectiveness and environmental friendliness, paper-based electronics are in accord with the thought principles of sustainable development. At the same time, paper’s porosity and rough microstructure with a plenty of surface functional groups can easily anchor other electronic materials compared with the abovementioned smooth organic substrates.…”

Destructive-Treatment-Free Rapid Polymer-Assisted Metal Deposition for Versatile Electronic Textiles

“…Chemical pretreatments such as NaOH mercerization, acid activation, and self-assembled monolayer modification have also been developed to improve the adhesion of catalysts. Recently, a mild chemical modification technology, namely, polymer-assisted deposition (PAMD), was reported. ,− In such process, functional polymers possessing a high affinity to the catalytic moieties are chemically grafted on target substrates. The functional polymers serve as anchors between the catalytic moieties and the substrates to address the wetting issue of catalytic moieties on the substrates.…”