Durable and tunable temperature responsive silk fabricated with reactive thermochromic pigments

Abstract

A durable and tunable multiple-color thermochromic natural silk is prepared with vinyl modified thermochromic pigments (VTPs) by thio-ene reaction. The VTPs is obtained by the hydrolysis-polycondensation between the siloxane groups of trietoxyvinylsilane (VTEO) and the hydroxy groups of thermochromic pigments (TP). The reversible thermochromic properties of VTPs perform well in the heating-cooling cycle. The color of VTPs gradually fades during heating, and returns to its origin color when cooled. Its thermal decomposition temperature is up to 272 ℃. The vinyl of VTPs can react with sulfhydryl of 3,3′,3′'-phosphinetriyltripropanoic acid hydrochloride (TCEP) treated silk fabrics and form covalent bonding between vinyl groups and sulfhydryl groups via thio-ene reaction. The color of fabricated thermochromic silk fabrics changes reversibly during heating and cooling cycles, which is consistent with the color change behaviors of VTPs. The sulfhydryl-vinyl covalent bonds formed between silk fibers and VTPs provide good washing fastness (3−4 grade) and rubbing fastness (3 grade). By combining thermochromic pigments with different color and transition temperatures, thermochromic silk fabrics with the features of multiple-color change, various responsive temperatures and continuous color change are fabricated, making it highly promising for smart textile application.