Polymeric Inverse Glasses for Development of Noniridescent Structural Colors in Full Visible Range

Abstract

Amorphous colloidal array with short-range order displays noniridescent structural colors due to the isotropic nature of the colloidal arrangement. The low angle dependence renders the colloidal glasses, which is 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 the blue region. To suppress the cavity mode and develop the colors in the 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 poly(ethylene glycol) dimethacrylate (PEGDMA) at a 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 backscattering 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 noniridescent structural colors.

Uniform Coating of Self-Assembled Noniridescent Colloidal Nanostructures using the Marangoni Effect and Polymers

“…1(f)]. As the structural color is developed by the internal structure rather than the surface, the deposit is expected to show non-iridescent color [7][8][9][10][11].…”

Structural Coloration with Nonclose‐Packed Array of Bidisperse Colloidal Particles

“…The colloidal glasses have isotropic structures with a short-range order, rendering them rotationindependent; [11,12] colloidal glasses still have angle dependence for specular reflection despite the dependency is lower than colloidal crystals. [13,14] To suppress colloidal crystallization and produce colloidal glasses, various approaches have been employed. For example, particles are rapidly concentrated by fast removal of dispersion media or centrifugation to kinetically capture amorphous array.…”

“…For example, the rate of colloidal concentration is controlled to modulate the degree of long-range ordering. [14,29,30] However, it is challenging to precisely control the rate and set the rate uniformly throughout the whole samples. Another way is to control a volume fraction of particles that have weakly repulsive interparticle potential.…”

“…To reduce the iridescence, colloidal glasses have been prepared. The colloidal glasses have isotropic structures with a short‐range order, rendering them rotation‐independent; colloidal glasses still have angle dependence for specular reflection despite the dependency is lower than colloidal crystals . To suppress colloidal crystallization and produce colloidal glasses, various approaches have been employed.…”

“…There are reports on the controlling colloidal arrangement between perfect crystal and glass. For example, the rate of colloidal concentration is controlled to modulate the degree of long‐range ordering . However, it is challenging to precisely control the rate and set the rate uniformly throughout the whole samples.…”