(511f) PMMA/TiO2 One-Dimensional Photonic Crystal Films with Structural Colors

Abstract: There are many examples of color that are not chemical in origin but rather physical in nature. Compared to pigment color, structural color has the characteristics of brightness, high saturation and fade-resistance. Artificial photonic crystals are the main source of structural color. Photonic crystals are a periodic array of media of different refractive micro-structures. Because one-dimensional photonic crystals have simple structure and facile preparation method, they have received widespread attention in recent years. In addition, as organic and inorganic complex photonic crystals may combine the advantages of both, they show promising prospect in application, such as coatings, naked eye inspection, displays, etc.

Here, nanoparticle-nanoparticle based organic-inorganic complex one-dimensional photonic crystal films were first designed with poly(methyl methacrylate) (PMMA) nanoparticles as low refractive index material and TiO₂ nanoparticles as a high refractive index one, and PMMA/TiO₂ stacks with structural colors were assembled through layer-by-layer spin coating. PMMA and TiO₂ nanoparticles with average diameter of about 40nm were first prepared. We used PMMA nanoparticles as low refractive index material and TiO₂ nanoparticles as the high refractive index one, and assembled PMMA/TiO₂ one-dimensional photonic crystals with structural colors through layer-by-layer spin coating. By adjusting the parameters of the nanoparticle dispersion and spin coating, such as the concentration of nanoparticles, rate and times of spin coating, and the stack number, we prepared angle-dependent structure colors of wide range from violet to nearly red. The morphology, reflective spectra and color properties of the one-dimensional photonic crystal films were investigated. This method can be effectively used for assembling other functional organic/inorganic complex one-dimensional photonic crystals for a wide usage.