CNT/cotton composite yarn for electro-thermochromic textiles

Electro-thermochromic yarn was prepared by wrapping pure cotton yarn on carbon nanotube/cotton composite yarn. The CNT/cotton composite yarn as the core yarn provides good electrical conductivity while the pure cotton yarn as the wrapped yarn plays a protective role and enables the color changing effect after coating with thermochromic inks. The electro-thermochromic yarn showed remarkable resistive heating and color-changing properties under different applied currents. Abundant and reversible color changes are clearly observed by coating the thermochromic inks onto the surface of yarn and fabric. Depends on the methods, a pure color changing fabric can be made from the electrothermochromic yarns and fabrics with color changing patterns can be achieved by printing the thermochromic inks into the fabrics from the CNT/cotton cored yarn. Moreover, when the current is 5 mA, the surface temperature of the CNT/cotton cored yarn can increase within several seconds to its maximum 60 oC. The average temperature of the electro-thermochromic fabric can reach up to 90 oC under 4 mA. The printed pattern changes color from deep rose to yellow when a current of 4 mA is applied on the electro-thermochromic fabric. The electro-thermochromic yarns and fabrics show repeatable and reversible color changing effects.