Rapid and Tunable Method To Fabricate Angle-Independent and Transferable Structurally Colored Films.

The assembly of monodisperse particles into colloidal arrays that diffract visible light through constructive interference is of considerable interest due to their resilience against color fading. In particular, noniridescent structurally colored materials are promising as a means of coloration for paints, inks, cosmetics, and displays because their color is angle independent. A rapid and tunable assembly method for producing noniridescent structurally colored colloidal-based materials that are pliable after fabrication is described. Structurally colored particle arrays were fabricated by centrifuging highly charged silica particles suspended in deionized water. By tuning the particle diameter, the colors displayed by the arrays spanned the visible spectrum while retaining angle-independent structural color. The color of centrifuged colloids of a single particle diameter was precisely controlled within 50 nm by modulating the particle concentration. The peak wavelength diffracted by the material was further tuned by altering the centrifugal rate and assembly time. Centrifugation assembly of particles in a polymer solution also produces noniridescent colloidal films, and the control of their color is reported. Together, these results offer design considerations for the centrifugation-based assembly of colloidal films with tunable structural color that are transferable after fabrication and are angle independent.