Robust Full‐Spectral Color Tuning of Photonic Colloids. Issue 6 (4th December 2022)

• Record Type: Journal Article
• Authors: Dodero, Andrea; Djeghdi, Kenza; Bauernfeind, Viola; Airoldi, Martino; Wilts, Bodo D.; Weder, Christoph; Steiner, Ullrich; Gunkel, Ilja
• Is Part Of: Small. Volume 19:Issue 6(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-04
• Subjects: 3D confined self‐assembly -- bandgap tunability -- block copolymers -- concentric lamellar microspheres -- photonic pigments; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202205438
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Creation of color through photonic morphologies manufactured by molecular self‐assembly is a promising approach, but the complexity and lack of robustness of the fabrication processes have limited their technical exploitation. Here, it is shown that photonic spheres with full‐color tuning across the entire visible spectrum can be readily and reliably achieved by the emulsification of solutions containing a block copolymer (BCP) and two swelling additives. Solvent diffusion out of the emulsion droplets gives rise to 20–150 µm‐sized spheres with an onion‐like lamellar morphology. Controlling the lamellar thickness by differential swelling with the two additives enables color tuning of the Bragg interference‐based reflection band across the entire visible spectrum. By studying five different systems, a set of important principles for manufacturing photonic colloids is established. Two swelling additives are required, one of which must exhibit strong interactions with one of the BCP blocks. The additives should be chosen to enhance the dielectric contrast, and the formation kinetics of the spheres must be sufficiently slow to enable the emergence of the photonic morphology. The proposed approach is versatile and robust and allows the scalable production of photonic pigments with possible future applications in inks for cosmetics and arts, coatings, and displays. Abstract : A methodology to create photonic pigments as dispersed and micrometer‐scale particles based on highly ordered concentric lamellar microspheres made of block copolymers is presented. Color tuning of the Bragg interference‐based reflection band across the entire visible spectrum is achieved by controlling the lamellar thickness by domain differential swelling. These photonic pigments find applications in inks, coatings, and displays.