New Article in ACS AM&I

posted May 1, 2016, 7:27 PM by Shin-Hyun Kim
Gun Ho Lee, Jae Young Sim, and Shin-Hyun Kim, "Polymeric Inverse Glasses for Development of Non-iridescent Structural Colors in Full Visible Range", ACS Applied Materials and Interfaces, accepted for publication (2016).

Amorphous colloidal array with short-range order displays non-iridescent structural colors due to isotropic nature of colloidal arrangement. The low angle dependence renders the colloidal glasses promising for various coloration applications. Nevertheless, the colloidal glasses are difficult to develop red structural color due to strong cavity-like resonance from individual particles in blue region. To suppress the cavity mode and develop the colors in full visible range, we prepare inverse glasses composed of amorphous array of air cavities with short-range order. To produce the structures in a simple and reproducible manner, monodisperse silica particles are dispersed in a photocurable resin of polyethylene glycol dimethacrylate (PEGDMA) at volume fraction of 0.3. The particles spontaneously form the amorphous array with short-range order, which is rapidly captured in polymeric films by photopolymerization of the resin. Selective removal of silica particles from the polymerized resin leaves behind amorphous array of air cavities. The inverse glasses display structural colors with negligible back-scattering in blue due to short optical path and low index in each cavity. Therefore, the colors can be tuned in full visible range by simply controlling the cavity size. The photocurable suspensions of silica particles can be patterned by photolithography, which enables the production of freestanding films containing patterned inverse glasses with non-iridescent structural colors.