Dyeable electroconductive cotton wrapped CNT yarn for multifunctional textiles

Conductive fiber plays increasingly important role in the field of multifunctional textile and smart clothing for the signal/power transmission, electrothermal function and so on. However, their major bottle necks are rigid, undyeable and limited durability. In this study, we manufactured a dyeable, washable and flexible conductive yarn by wrapping cotton roving fiber (wrapped fiber) on the surface of Carbon Nanotube (CNT) fiber (core yarn) and twisting them together by core-spun yarn spinning technique, named as cotton wrapped CNT yarn (CWC yarn). The appearance and flexibility of the CWC yarn are similar with the cotton yarn, but showing excellent conductivities of 100 Ω/cm, (undyed CWC yarn) and 50 Ω/cm (dyed CWC yarn). The electrothermal temperature of the CWC yarn with length of 5 cm reached 70 °C with applied voltage of 20 V, which was even higher than that of the pristine CNT yarn (60 °C). Furthermore, its electrical and electrothermal property changed slightly after being loaded, bent, knotted, fold-released (100 cycles) and washed, showing excellent durability. In addition, the electrochromatically dyed CWC yarn after weaving or embroidering into fabrics displayed changed colors with the various applied voltages. This work demonstrated a simple and referential method to design dyeable and washable multifunctional yarns for wearable applications.