Filaments for 3D Printing of Iridescent Structural Colors

Abstract Inspired by nature, this work presents a scalable method to produce opalescent 3D printing filaments with angle‐dependent structural color. Compared to conventional colorants, these colors provide a more vivid appearance, possess the ability to dynamically change in response to alterations of illumination, and may feature superior longevity as well as durability. Particle synthesis via emulsion polymerization in starved‐feed mode is utilized to achieve a tailored core–shell particle architecture. During processing, the thermoplastic polyacrylate‐based shells form a continuous matrix, wherein the pristine polystyrene cores self‐assemble. The colloidal ordered structure thus formed selectively scatters light according to Bragg's law. Adjusting particle size makes the perceived colors easily tunable over the visible spectrum. The filaments are printable on entry‐level printers with comparable settings to commercial filaments and state‐of‐the‐art print quality. With this work, sustainable 3D printing of iridescent objects with a novel and superior coloration strategy becomes possible for everyone – from hobbyists over customized goods and industrial prototypes to serial production.