DOI: https://doi.org/10.29363/nanoge.emlem.2024.002
Publication date: 13th July 2024
The pursuit for innovative materials with vibrant, enduring colors resistant to chemical or photobleaching is a critical aim in industries like paints, cosmetics, and displays. This goal has gained importance due to continuous technological progress and to this end nature serves as a significant source of inspiration, showcasing a variety of optical effects developed through evolution, such as the brilliant iridescence of bird feathers and the adaptive colors of camouflaging chameleons. These effects often stem from complex internal structures at the nano- and microscale, resulting in unique light-matter interactions. Particularly intriguing is the structural coloration produced by periodic arrangements of two or more dielectric materials with different refractive indices, where the lattice dimensions are comparable to the wavelength of visible and near-infrared radiation. These photonic materials hold the potential for significant societal benefits due to their light-manipulating capabilities, which are anticipated to drive multiple technological breakthroughs. In this framework we present the fabrication of hybrid organic-inorganic photonic microparticles with unique functionalities achieved through the three-dimensional confined self-assembly of block copolymers (BCPs) within emulsion droplets. By carefully selecting the type of BCP and the processing conditions, we can produce either highly ordered structures (e.g., concentric or stacked lamellae) or quasi-random structures with short-range order. These structures consist of alternating domains with differing refractive indices, resulting in strong light reflection that can be tuned across the visible spectrum. Additionally, we integrate these structurally colored microparticles with various light-emitting inorganic colloidal semiconductor nanomaterials. This integration is achieved quickly through a straightforward, one-step solvent evaporation co-assembly process within emulsion droplets. By fine-tuning the enthalpic and/or entropic interactions between the block copolymers and the ligands on the nanomaterials' surfaces, we control the spatial arrangement of the inorganic nanomaterials within the resulting nanostructured particles. The resulting hybrid photonic structure retains its characteristic structural color while also functioning as a dielectric environment for the embedded quantum dots thus modifying their emission properties.