SMART COLORANTS FOR TEXTILE

Commercial textile colorants are generally required to produce constant, predictable and consistent shades of a wide range of shade gamut. The shades produced in the yarns and fabrics should be permanent as far as technically feasible on exposure to effects of light, washing, abrasion, chemicals etc. There is a potential for niche market for textiles that show a change in shade in response to external stimulus. The novel effects obtained due to application of chromic colorants and glow in dark or luminous colorants have been studied by various researchers. The reversible change of color in response to external stimuli is known as chromism. Chromic colorants are classified on the basis of nature of external stimuli that the colorant responds to. The major classes of chromic colorants for textiles are thermochromic that respond to changes in temperature, photochromic that are induced by exposure to UV light. The other major classes are solvatochromic colors which respond to changes in polarity of the solvents and electrochromic colorants that show change on gain or loss of electrons. The present paper attempts to review the work done by various researchers to study the structure, properties and application to textiles. This paper covers the research work carried out on thermochromic, photochromic and glow-in-the dark colorants mainly as these are the most widely used smart colorants applied on textile substrates.