Robust Structurally Colored Coatings Composed of Colloidal Arrays Prepared by the Cathodic Electrophoretic Deposition Method with Metal Cation Additives

Katagiri Kiyofumi

Uemura Kensuke

Uesugi Ryo

Tarutani Naoki

Inumaru Kei

Uchikoshi Tetsuo

Seki Takahiro

Takeoka Yukikazu

ACS Applied Materials and Interfaces

Structurally colored coatings composed of colloidal arrays of monodisperse spherical particles have attracted great attention owing to their versatile advantages, such as low cost, resistance to fading, and low impacts on the environment and human health. However, the weak mechanical stability is considered to be a major obstacle for their practical applications as colorants. Although several approaches based on the addition of polymer additives to enhance the adhesion of particles have been reported, the challenge remains to develop a strategy for the preparation of structurally colored coatings with extremely high robustness using a simple process. Here,we have developed a novel approach to fabricate robust structurally colored coatings by cathodic electrophoretic deposition. The addition of a metal salt,i.e., Mg(NO3)2, to the coating dispersion allows SiO2particles to have a positive charge, which enables the electrophoresis of SiO2 particles toward the cathode. At the cathode, Mg(OH)2 co-deposits with SiO2 particles because OH−ions are generated by the decomposition of dissolved oxygen and NO3−ions. The mechanical stability of the colloidal arrays obtained by this process is remarkably improved because Mg(OH)2 facilitates the adhesion of the particles and substrates. The brilliant structural color is maintained even after several cycles of the sandpaper abrasion test. We have also demonstrated the coating on a stainless steel fork.This demonstration reveals that our approach enables a homogeneous coating on a complicated surface. Furthermore, the high durability of the coating is clarified because the coating did not peel off even when the fork was stuck into a plastic eraser. Therefore,the coating technique developed here will provide an effective method for the pervasive application of the structural color as a colorant.

structural color

colloidal arrays

abrasion test

electrophoretic deposition

eng

American Chemical Society

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsami.0c10588.

This is not the published version. Please cite only the published version. この論文は出版社版ではありません。引用の際には出版社版をご確認、ご利用ください。

[ISSN] 1944-8244

[ISSN] 1944-8252

[DOI] 10.1021/acsami.0c10588

[DOI] https://doi.org/10.1021/acsami.0c10588