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

摘要

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 degrees C) to light blue (45 degrees C) and white (80 degrees 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 degrees 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 degrees 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.