Materials Chemistry, Short Talk
Mat-013

Multifunctional Photonic Microparticles via Block Copolymer Self-Assembly: From Structural Color to Magnetically Responsive Optical Materials

A. Dodero1,2, G. Mazzotta3,2*, N. R. Schwarz1,2*, S. Bertucci1*, R. Schobinger 1*, D. Peddis4*, D. Comoretto4*, U. Steiner1,2*
1Adolphe Merkle Insitute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland, 2NCCR Bio-Inspired Materials, Chemin des Verdiers 4, 1700 Fribourg, Switzerland, 3Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland, 4Department of Chemistry and Industrial Chemistry, University of Genoa, Via Dodecaneso 31, 16146 Genoa, Italy

Controlling structural color through scalable, precise, and multifunctional material design remains a key objective in the development of next-generation photonic systems. Here, we present a robust fabrication platform based on the confined self-assembly of block copolymers (BCPs) within emulsion droplets, enabling the production of photonic microparticles with lamellar architectures and vivid structural color. The process allows precise tuning of the photonic bandgap across the visible spectrum by modulating domain periodicity and refractive index contrast through supramolecular additives and low molecular weight swelling agents.1

This approach addresses key challenges in photonic material design by combining structural robustness, spectral tunability, and compatibility with scalable emulsification methods. It further enables the incorporation of functional nanomaterials – such as quantum dots, plasmonic, and magnetic nanocrystals – into specific block copolymer domains, resulting in hybrid microparticles that integrate photonic coloration with tailored emission,2 plasmonic,3 or magnetic properties. Additionally, we demonstrate the fabrication of anisotropic, rod-like photonic microparticles by tuning emulsion conditions and embedding magnetic nanoparticles into the BCP matrix. These rods exhibit orientation-dependent color and can be dynamically aligned using external magnetic fields, enabling programmable optical responses.

The resulting materials offer a promising platform for a wide range of applications. In particular, we demonstrate the formulation of water-based structural color coatings by combining photonic microparticles with broadband absorbers and polymeric binders, yielding vibrant, fade-resistant paints suitable for industrial application on surfaces, packaging, textiles, and cosmetics. Beyond coatings, these materials show strong potential in sensing, optical tagging, anti-counterfeiting, display technologies, and wearable devices where their tunable, angle-independent, or magnetically reconfigurable coloration can be exploited for dynamic, responsive, and secure photonic systems.

[1] A. Dodero, K. Djeghdi, V. Bauernfeind, M. Airoldi, B. D. Wilts, C. Weder, U. Steiner, I. Gunkel, Small 2023, 19, 2205438.

[2] S. Bertucci, D. Piccinotti, M. Garbarino, A. Escher, G. Bravetti, C. Weder, P. Lova, D. Comoretto, U. Steiner, F. Di Stasio, A. Dodero, Nanoscale 2025, 17, 10194.

[3] A. Escher, G. Bravetti, S. Bertucci, D. Comoretto, C. Weder, U. Steiner, P. Lova, A. Dodero, ACS Macro Lett 2024, 13, 1338.