Ni-P metallization of nylon 6,6 yarns with varying twist numbers by supercritical CO2 catalyzation toward weavable devices

Abstract

Weavable devices are innovative fabric-based electronics created by weaving yarns with various functions into a single cloth, enabling multifunctionality beyond traditional wearable devices. Electrically conductive yarns are essential for this integration, and in practical applications, yarns are prepared with varying twist numbers. This study investigates the metallization of nylon 6,6 yarns using a supercritical CO₂-assisted NiP electroless plating method and examines the influence of twist numbers on metallization characteristics. The results show that increasing the twist number significantly decreases the electrical resistance of Ni-P/nylon 6,6 composite yarns, underscoring the critical role of yarn structure in electrical conductivity. Energy-dispersive X-ray spectroscopy (EDS) analysis indicates that higher twist numbers (0 T/m to 865 T/m) improve the distribution of Pd catalysts on scCO₂-catalyzed nylon 6,6 yarns. Additionally, scanning electron microscope (SEM) observations and EDS analysis show that increasing the twist number leads to thicker and more uniform NiP coatings, thereby improving the electrical performance. Overall, this study demonstrates that optimizing twist number is key to improving the metallization quality and electrical properties of nylon 6,6 yarns for advanced weavable electronic applications.