The beautiful structural colors in bird feathers are some of the brightest colors in nature, and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index, and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles’ diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications.

A novel approach for creating non-iridescent bright structural color materials from polydopamine (PDA) black particles that mimic melanin granules found in nature is presented. 43 290 3393; Tel: +81 43 290 3393 † Electronic supplementary information (ESI) available. See

A free-standing polymer brush film with tailored thicknesses based on a colorless polydopamine (PDA) thin layer is prepared and characterized. The surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) is performed on a PDA layer with thickness of ca. 6 nm, which generated an optically transparent and colorless free-standing PHEMA brush film (1.5 cm × 1.5 cm). Because the cross-linked PDA layer is used as the base for the polymer brushes, the reported method does not require cross-linking the polymer brushes. The free-standing film thicknesses of ≈16-75 nm are controlled by simply changing the ATRP reaction time. The results show that the free-standing PHEMA brush film transferred onto a plate exhibits a relatively smooth surface and is stable in any solvent.

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