Smart cotton fabric screen-printed with viologen polymer: photochromic, thermochromic and ammonia sensing

Abstract A multi-responsive chromic textile was conveniently fabricated by screen-printing with a covalent organic polymer of viologen (COP 2+ ) on the surface of cotton fabric, which was endowed with ammonia sensing, photochromic and thermochromic capabilities. The COP 2+ coated fabric (CCF) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The coating treatment endowed the fabric with fast response to ammonia gas, ultraviolet light and heat without compromising its breathability, flexibility, and comfortability. The color of CCF turned from yellow to green instantly when exposed to ammonia gas and quickly returned yellow when removed from the stimulus. The reversible color transition process can also be induced by UV light (exposure for 10 s) or heat (110 °C) and is cyclable. This durable multi-responsive textile has great potential to be used as flexible sensor for environmental monitoring. Graphic abstract