Preparation Of Photochromic Wool Fabrics Based On Thiol-halogen Click Chemistry

In recent years,with the increasing awareness of novelty and functionality of textiles,photochromic textiles are increasingly attracting more and more attention and have been widely used in people’s life.In order to meet the pursuit of unique aesthetic concepts and avant-garde changes in the color of textiles,some researchers have begun to introduce many color-changing materials to the textile and apparel fields of daily life,so that the textiles can demonstrate various color changes under different conditions.This paper proposes to graft photochromic compounds onto wool fabrics based on thiol-halogen click chemistry to impart excellent photochromic properties,while also providing a simple,highly efficient modification of wool fabrics under mild conditions.In this paper,a novel photochromic compound 9’-(2-bromo-2-methylethoxycarbonyl)-1,3,3-trimethyl-spiro[2H-indole-2,3’-[3H]naphtha[2,1-b][1,4]oxazine]was successfully synthesized by chemical method.The structure of the product was characterized by fourier transform infrared spectroscopy(FT-IR),UV/Vis spectrophotometer(UV)and nuclear magnetic resonance spectroscopy(~1H-NMR)after isolation and purification.The results showed that the structure of the product was consistent with the structure of the desired photochromic compound.Secondly,the wool fiber protein molecule contains a certain number of disulfide bonds (-S-S-),and tris(2-carbonxyethyl)phosphine hydrochloride(TCEP)was a very efficient and mild mercaptan reductant,which can reduce the-S-S-bonds into sulfhydryl groups(-SH).Therefore,TCEP was used to pretreat the wool fabric to obtain reactive-SH groups.Finally,the photochromic compound was grafted onto the wool fabric by using the-Br of the molecular terminal of the synthesized photochromic compound and the-SH on the pretreated wool fiber by click chemistry reaction.The results indicated the resultant photochromic wool fabric has excellent photochromic properties and good fatigue resistance.TheΔE value of the photochromic wool fabric after UV irradiation reaches 35.83.After 10 minutes of discoloration,the fabric recovered to its original color.Meanwhile,theΔE value of the photochromic wool fabric was 1.03 and the fading rate was up to 97%,which indicates that the photochromic wool fabric has a quick fading time.In addition,theΔE value of the fabric was decreased from 35.83 to 26.5 after 20 cycles of UV irradiation and fading,indicating that the fabric still maintains a good fatigue resistance.After five standard washing,theΔE value of the photochromic wool fabric can still be maintained at about27.The results showed that the photochromic wool fabric possesses good washing fastness.The total felting shrinkage was only about 7%for the photochromic wool fabric after 5 consecutive cycles of 5A washing and tumble drying according to the ISO 6330 standard,compared to about25%for the untreated wool fabric.Therefore,it can be concluded that the dimensional stability of the wool fabric after photochromic treatment was greatly improved and the felting shrinkage effect was remarkable.