Efficient preparation of liquid photonic crystals and their application in bionic structural coloration of textiles

Photonic crystals (PCs) constructed by colloidal self-assembly have attracted increasing attention in textile field because of their brilliant structural colors produced without using chemical colorants (dyes and pigment). And, the rapid and large-scale production of PC structurally colored textiles could be achieved via self-assembly of high-mass fractions of liquid photonic crystals (LPCs). However, the extensive and efficient preparation of LPCs still remains a challenge. In this work, the rotary evaporation method is applied for rapid preparation of LPCs, and a three-dimensional barrier based on charge repulsion and space obstruction was constructed by the syn-ergistic effect of anionic/nonionic surfactants. As a result, the key issue that, the colloidal nanospheres aggregate and sediment more and more seriously with increasing the mass fraction of nanospheres during rotary evapo-ration, was resolved, and the LPC system with pre-crystallized form was efficiently prepared from the mono -dispersed nanosphere system with low mass fraction of 30 wt% or lower. The mass fraction of nanospheres in the prepared LPC system enriched 55%, and the optical properties of LPCs could be controlled by the mass fraction and/or the particle size of nanospheres. With the increase of the nanosphere mass fraction in the system, the pre -crystallization region increased, and the structural color became much brighter. The prepared LPCs exhibited excellent dynamic reversibility of the assembled structure. Under the applied external force, the LPCs dis-assembled, as it could be concluded from the vanishing structural color. After removing the external force, the structure was quickly reconstructed into a pre-crystallized LPC in around 10 s, and the structural color reap-peared, showing a fast response performance of the LPC. Finally, the prepared LPC was applied onto a flexible textile substrate under external shear force. Due to the characteristics of LPC, it quickly reconstructed to form a uniform LPC film on the substrate surface, which rapidly transformed into a solid PC film with brilliant structural colors, realizing a rapid large-scale preparation of PC structural color fabrics.