Bright, Angle-Independent, Solvent-Responsive, and Structurally Colored Coatings and Rewritable Photonic Paper Based on High-Refractive-Index Colloidal Quasi-Amorphous Arrays

Abstract

Bright structural colors with an angular-independent character are in increasing demand in many fields such as pigments, buildings, sensors, color displays, and anti-counterfeiting labels. However, the structural colors produced by amorphous colloidal assemblies with low refractive index contrast or without black additives often exhibit low color visibility and low liquid-bleaching resistibility. Herein, large-scale and angleindependent structural colors were constructed from Fe 3 O 4 @SiO 2 colloidal quasiamorphous arrays (QAAs) prepared through a rapid "spraying" process. Due to the high-refractive-index and intrinsic black nature of Fe 3 O 4 , the coatings exhibit high brightness of structural colors even on white substrates under ambient lighting conditions. Moreover, as-obtained structural colors possess the ability of antiliquid bleaching and solvent-responsiveness. More importantly, flexible Fe 3 O 4 @SiO 2 /PDMS photonic paper can be fabricated by permeation of PDMS into the voids of Fe 3 O 4 @SiO 2 colloidal QAAs. This QAAs-based photonic paper shows the ability to infuse silicone oils into its structure, locally swelling it and changing the reflected color. In turn, the resulting colored patterns can be easily erased by applying ethanol or low molecular weight silicone oils. The as-prepared photonic paper exhibits excellent durability and is rewritable at least 50 times without any significant changes in performance. Compared with the traditional long-range ordered photonic crystals, the rapidly prepared QAAs-based photonic coatings have unique advantages in the applications of permanents, color coatings, color printing, liquid colorimetric sensors, rewritable photonic paper, etc. because of the good structural color performance and are suitable for rapid and large-area preparation.

Low-Angle-Dependent Anticounterfeiting Label Decoded by Alcohol Tissue Wiping Based on a Multilayer Photonic Crystal Structure

“…Therefore, the angle dependence of the information PC layer needed to be reduced by means such as increasing the effective refractive index of the whole microstructure. 37,38 Here, we designed an anticounterfeiting label using a high refractive index (RI) material (CdS PC infiltrated by polymer) as an information layer (Scheme 1a). As the information carrier, the CdS/polymer PC demonstrates a bright low-angledependent structural color due to the high RI of CdS spheres (n∼2.0).…”

Multi-responsive, flexible, and structurally colored film based on a 1D diffraction grating structure

“…Structural colors are ubiquitous in nature and daily life, such as birds (Stavenga et al, 2011;Michelson, 1911), insects (Hsiung et al, 2017;Biro ´et al, 2007), reptiles (Teyssier et al, 2015), petals (Whitney et al, 2009), rainbows, and compact discs (Whitney et al, 2009). Inspired by these models, a series of materials have been developed to mimic these structures for applications such as coating (Wen et al, 2021), textile (Wang et al, 2019), display (Ohtsuka et al, 2015;Bechinger et al, 1996;Wang et al, 2015), sensor (Zhang et al, 2018;Kou et al, 2019;Li et al, 2020), and anti-counterfeiting (Heo et al, 2016;Yao et al, 2021). Especially, reversible stimuli-responsive structural colors have received much attention in recent years because of their ability to exhibit a specific color in a particular situation.…”

UV-Responsive, wide color gamut, inkless dynamic photonic paper enabled by disulfide-containing polyurethane based Fabry-Perot resonant cavity

“…[7][8][9][10][11][12] Furthermore, by introducing an active substance into or as the building blocks of the microstructure, dynamic photonic paper with tunable color and patterns can be achieved based on the responsive feature of the building blocks under external stimuli. [13][14][15][16][17] As one of the most commonly reported dynamic photonic paper, responsive photonic crystals generate dynamic color patterns by combining with a responsive polymer and changing the effective refractive index or lattice constant in the specific area under the stimuli, [18][19][20][21][22] which are widely used in information security materials and anti-counterfeiting materials. 23,24 However, in order to obtain color patterns with high quality, specific fabrication processes, which are complicated and time-consuming, are needed to prepare photonic crystals with a strictly ordered periodic structure, greatly hindering the practical applications of dynamic photonic paper.…”