Multifunctional, oxidation-resistant, high-conductivity inks based on core-shell Cu@Ag nanorods for flexible printed electronics

First reported liquid-phase synthesis of copper nanorods from a highly concentrated copper precursor under low-alkalinity and low structure-directing agent conditions. • A highly oxidation-resistant conductive ink was prepared by electroless plating and by using an organosilane-modified polyurethane as the continuous phase. • The resulting conductive ink enables stable performance in flexible electronics applications, including motion sensing, physiological monitoring, human-machine interfaces, wireless communication, and electromagnetic interference shielding. Functional conductive inks are foundational to flexible electronics and demand tight control over the oxidation resistance and conductivity of the metallic phase, together with the rheology, mechanical compliance and thermal stability of the continuous phase, to optimise printability and device performance. Morphology control of the conductive phase is also essential; however, scalable, low-cost and environmentally benign syntheses remain challenging. Here reporting a strategy that addresses these barriers. Polyether diamine (ED-2003) serves as a structure-directing agent under low-alkalinity, ice-bath conditions, enabling, for the first time, large-scale copper nanorod production from a high-concentration precursor system. A facile, contamination-free electroless silver-plating step forms Cu@Ag core-shell nanorods with excellent oxidative stability, while functional-group incorporation into the polymer backbone of the continuous phase concurrently improves flexibility, thermal robustness and nanorod dispersibility. The resulting ink delivers ultrahigh conductivity (386,093.33 S cm −1 at 19 wt% solids) and retains 383,192.56 S cm −1 after one year in air. It prints high-resolution, uniform conductive patterns on latex, (polyurethane) PU, cellulose and PET, and the printed films maintain nearly constant conductivity after 10,000 bending cycles, and printed traces are stretchable to 1000%. Collectively, these results highlight the broad applicability of the ink in flexible printed electronic products and establish a new paradigm for the scalable manufacture of high-performance, low-cost printed conductive inks for flexible electronics. Download: Download high-res image (270KB) Download: Download full-size image