A new approach for the preparation of durable and reversible color changing polyester fabrics using thermochromic leuco dye-loaded silica nanocapsules

Abstract

Durable, reversible color changing polyester fabrics were successfully fabricated via a new approach of dyeing with thermochromic leuco dye-loaded silica nanocapsules (TLD@SiO₂). TLD@SiO₂ was prepared via tetraethyl orthosilicate hydrolyzation and condensation on the surfaces of emulsified thermochromic leuco dye (TLD) nano-droplets by a sol–gel method. The TLD@SiO₂ was about 20 nm in size, and its shell could provide protection for TLD. The color of TLD@SiO₂ changed from dark blue (25 °C) to light blue (45 °C) and white (80 °C), reversibly. The thermochromic mechanism originated from the conjugation structure conversion of the crystal violet lactone which was confirmed by density functional theory calculations. The shell materials (Si–O–Si) of TLD@SiO₂ could be hydrated in water with temperature increase and produced hydrophilic hydroxyl groups for further treating polyester fabrics. These resulting polyester fabrics exhibited excellent thermochromic performance with a color transition temperature of 45 °C. Their color reversibly changed from dark blue (K/S = 12) to light blue (K/S = 2) at 610 nm for more than 50 times. Meanwhile, thermochromic polyester fabrics dyed at 130 °C displayed good color fastness. The washing, dry rubbing and wet rubbing fastness of the thermochromic polyester fabrics all reached above 4 grades, and the thermochromic polyester fabrics showed good solvent resistance.