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We report the fabrication and characterisation of near-IR reflecting films and coatings based on shear-assembled crystalline ensembles of polymer composite microspheres, also known as "polymer opals". Extension of the emulsion polymerisation techniques for synthesis of tractable larger core-interlayer-shell (CIS) particles, of up to half a micron diameter, facilitates the engineering and processing of thin-film synthetic opals, with a tunable photonic stopband spanning an extended spectral range of λ ≈ 700–1600 nm. Samples exhibit strong "scattering cone" interactions, with considerable angular dependence and angle tuning possible, as measured with a goniometric technique. These intense optical resonances in the near-IR, particularly within the important region around λ ~ 800 nm, combined with an appreciable translucency within the visible light spectrum, is indicative of the potential applications in coatings technologies and solar cells. [ABSTRACT FROM AUTHOR]

Three-dimensional goniometric measurements of structural color from melt-sheared polymer nanoparticle composites is presented revealing high-angle features arising from Bragg scattering. These features are presented in terms of 'scattering cones' from full 180° hemispherical scans showing the spectroscopic and angular properties of these scattering spots. This work identifies the Miller indices of the photonic crystal planes responsible for these features and makes further observations as to the appearance of this scattering in the context of these structures as quasi-ordered systems. We probe structural color metrics such as peak wavelength and the tunability of reflectance intensities. As such, this report contributes towards an improved understanding of Bragg scattering and structural color from structures with inherent disorder. The complexity and specificity of color quality across the scattering hemisphere is an important consideration for practical uses such as in sensing applications, and we suggest that soft photonics, in particular, are strong candidates in high-angle color uses. [ABSTRACT FROM AUTHOR]

We report on shear-ordered polymer photonic crystals demonstrating intense structural color with a photonic bandgap at 270 nm. Our work examines this UV structural color, originating from a low refractive index contrast polymer composite system as a function of the viewing angle. We report extensive characterization of the angle-dependent nature of this color in the form of 'scattering cones', which showed strong reflectivity in the 275–315 nm range. The viewing range of the scattering was fully quantified for a number of planes and angles, and we additionally discuss the unique spectral anisotropy observed in these structures. Such films could serve as low-cost UV reflection coatings with applications in photovoltaics due to the fact of their non-photobleaching and robust mechanical behavior in addition to their favorable optical properties. [ABSTRACT FROM AUTHOR]