Understanding the Electrophoretic Deposition Accompanied by Electrochemical Reactions Toward Structurally Colored Bilayer Films

Abstract

Safe, low-cost structurally colored materials are alternative colorants to toxic inorganic pigments and organic dyes. Colloidal amorphous arrays are promising structurally colored materials because of their angle-independent colors. In this study, we focused on precise tuning of the chromaticity by preparing bilayer colloidal amorphous arrays through electrophoretic deposition (EPD). Systematic investigations with various EPD conditions clarified the contributions of each condition to the EPD process and the competing electrochemical reactions, which enabled us to prepare well-colored coatings. EPD films composed of colloidal amorphous array bilayers were successfully synthesized with controlled film thickness. Chromaticity of the films was found to be precisely controlled by the EPD duration. We believe that this understanding of the EPD process and its application to synthesis of structurally colored bilayer films will bring structurally colored materials closer to practical industrial use.

Influences of Heat Treatment, Particle Arrangement, and Binder Addition on the Mechanical Robustness of Structurally Colored Coatings Formed with Monodisperse SiO2 Spheres

“…Against this background, we developed a novel strategy for the preparation of structurally colored coatings with colloidal array structures. [33][34][35][36][37][38] The electrophoretic deposition (EPD) method can be considered to be one of the most versatile methods to prepare coatings, including colored thin films, from colloidal dispersions. [39][40][41] The EPD technique allows us to create coatings with complicated shapes and differentiate between colloidal crystalline and amorphous structures.…”

Multi-color inkless UV printing using angle-independent structural color paper

“…23 In comparison, the concept of amorphous structural color has recently been exploited as another unique coloration approach to improve structural color printing. [24][25][26] These structures are essentially isotropic with short-range order on a length scale comparable to the optical wavelengths of the incident light, and therefore the reflection spectra become almost angle independent based on wavelength-specific constructive interference. [27][28][29] Amorphous structural color is more natural and familiar to human beings.…”