Crafting Nanostructured\nHybrid Block Copolymer–Gold\nNanoparticles by Confined Self-Assembly in Evaporative Droplets

Hybrid organic–inorganic nanostructures offer\nsignificant\npotential for developing advanced functional materials with numerous\ntechnological applications. However, the fabrication process is often\ntedious and time-consuming. This study presents a facile method for\nfabricating block copolymer-based photonic microspheres incorporating\nplasmonic gold nanoparticles. Specifically, the confined self-assembly\nof poly(styrene)-<i>b</i>-poly(2-vinylpyridine) in emulsion\ndroplets allows the formation of spherical, noniridescent, concentric\nlamellar structures, i.e., onion-like particles that are subsequently\ninfiltrated with gold salt. Using ethanol as a preferential solvent\nallows the loading of metal ions exclusively into the poly(2-vinylpyridine)\ndomains, which are subsequently reduced, leading to the <i>in\nsitu</i>, spatially controlled formation of gold nanoparticles.\nThe hybrid structures exhibit a well-defined photonic bandgap and\nplasmonic resonance at low gold concentrations. These results demonstrate\nthe feasibility of fabricating optically active photonic structures\ncomprising metal nanoparticles in a block copolymer array via a simple\ntwo-step fabrication process.