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Abstract Plasmonic metal nanostructures can simultaneously scatter and absorb light, with resonance wavelength and strength depending on their morphology and composition. This work demonstrates that unique dichroic effects and high‐contrast colour‐switching can be achieved by leveraging the resonant scattering and absorption of light by plasmonic nanostructures and the specular reflection of the resulting transmitted light. Using core/shell nanostructures comprising a metal core and a dielectric shell, we show that their spray coating on reflective substrates produces dichroic films that can display colour switching at different viewing angles. The high‐contrast colour switching, high flexibility in designing multicolour patterns, and convenience for large‐scale production promise their wide range of applications, including anticounterfeiting, mechanochromic sensing, colour display, and printing. 

We report here that dissolution and regrowth of resorcinol formaldehyde (RF) colloidal particles can occur spontaneously when they are subjected to etching in solvents such as ethanol and tetrahydrofuran, resulting in the formation of hollow nanostructures with controllable shell thickness. The hollowing process of the RF particles is attributed to their structural inhomogeneity, which results from the successive deposition of oligomers with different chain lengths during their initial growth. As the near-surface layer of RF colloids mainly consists of long-chain oligomers while the inner part consists of short-chain oligomers, selective etching removes the latter and produces the hollow structures. By revealing the important effects of the condensation degree of RF, the etching time and temperature, and the composition of solvents, we demonstrate that the morphology and structure of the resulting RF nanostructures can be conveniently and precisely controlled. This study not only improves our understanding of the structural heterogeneity of colloidal polymer particles, but also provides a practical and universal self-templated approach for the synthesis of hollow nanostructures. 

While titania and carbon are conventionally perceived as white and black materials, here we show that their combination in the form of composite hollow nanoshells can display striking colors with considerably high contrast through resonant Mie scattering. Our unique design utilizes hollow nanostructures to produce the color by minimizing random multiple scattering and the incorporated carbon species to act as an internal black background to suppress multiple scattering and enhance the color contrast. Synthesized through a simple sol–gel process followed by high-temperature carbonization, these hollow carbon-containing titania (C-TiO 2 ) nanoshells can exhibit variable bright colors from purple to blue and green by controlling their diameter. They can be conveniently used as alternative pigments in many color-related applications, with the advantages of high chemical and optical stability and low toxicity that are associated with titania and carbon materials and the structural coloration mechanism. In addition, as the visible Mie scattering responds rapidly and reversibly to changes in the surrounding medium, these nanoshells may also serve as active color components for many applications that require dynamic color switching, such as signage and displays, colorimetric sensors and detectors, and anti-counterfeiting devices. 

Abstract Conventional templating synthesis confines the growth of seeds in rigid spaces to achieve faithful morphological replication. Herein, we explore the use of spherical shape‐deformable polymeric nanoshells to regulate the anisotropic growth of Ag nanoplates. The flexible shells deform adaptively to accommodate the initial overgrowth of the seeds but restrict the growth in the directions where the shells are fully stretched, eventually producing nanoplates with an unconventional circular profile. The diameter of the final Ag nanoplates can be precisely predicted by stretching and flattering the nanoshells into a plate‐like capsule while retaining their original internal surface area. Furthermore, unlike conventional templates, the polymer shells eventually turn themselves into a conformal coating that binds to the surface of the full‐grown Ag nanoplates and significantly enhances their stability against oxidative etching.