Enhanced thermal and electrical properties of waterborne PVOH-based Cu@Ag conductive composites

Waterborne conductive composites hold promise for flexible electronics, yet achieving high conductivity, strong adhesion, and long-term stability remains a challenge. This study developed a waterborne conductive composite based on a multi-component poly(vinyl alcohol) (PVOH) organic carrier and Cu@Ag core–shell particles. Optimization of the PVOH blend composition and the H₂O-to-propylene glycol (PG) ratio yielded a carrier with balanced solubility, printability, and stable viscosity, while retaining sufficient hydroxyl groups for effective filler particle wetting and adhesion. The Cu@Ag filler leverages the cost-effectiveness and conductivity of copper alongside the oxidation resistance of silver, facilitating the formation of conductive contacts at low processing temperatures. The melting temperature of the optimized ternary PVOH composites is approximately 44.6 °C higher than that of single-component PVOH, indicating improved thermal resistance and chain packing. At the filler loading of 75–80%, the printed composite films form the percolation plateau, demonstrating low resistivity of 9.78 × 10⁻⁶ Ω·cm. These composites also possess strong substrate adhesion and good stability, with the resistivity changing by approximately 5% over one year and maintaining performance after aging at 85 °C/85% relative humidity. This work presents an environmentally friendly approach to fabricating low-temperature printable conductors for flexible electronics.