Crafting Nanostructured Hybrid Block Copolymer-Gold Nanoparticles by Confined Self-Assembly in Evaporative Droplets

Hybrid organic-inorganic nanostructures offer significant potential for developing advanced functional materials with numerous technological applications. However, the fabrication process is often tedious and time-consuming. This study presents a facile method for fabricating block copolymer-based photonic microspheres incorporating plasmonic gold nanoparticles. Specifically, the confined self-assembly of poly(styrene)-b-poly(2-vinylpyridine) in emulsion droplets allows the formation of spherical, noniridescent, concentric lamellar structures, i.e., onion-like particles that are subsequently infiltrated with gold salt. Using ethanol as a preferential solvent allows the loading of metal ions exclusively into the poly(2-vinylpyridine) domains, which are subsequently reduced, leading to the in situ, spatially controlled formation of gold nanoparticles. The hybrid structures exhibit a well-defined photonic bandgap and plasmonic resonance at low gold concentrations. These results demonstrate the feasibility of fabricating optically active photonic structures comprising metal nanoparticles in a block copolymer array via a simple two-step fabrication process.