Chemically Controlled Order and Geometries of Plasmonic Patches at Soft Curved Interfaces

Creating ordered plasmonic nanoparticle lattices on soft, curved templates remains challenging due to curvature‑induced frustration and kinetic trapping at fluid interfaces. Here we report a chemically programmable route to organize 5‑nm gold nanoparticles (AuNPs) into hexagonally ordered surface "patches" on crosslinked liquid-crystalline polymer nanoparticles (LCNPs) synthesized via miniemulsion polymerization. We find that, contrary to expectations from elastic templating alone, AuNPs remain predominantly surface‑dispersed in the absence of proper co-stabilizer. By tuning the identity and concentration of hydrophobic co‑stabilizers, we induce a controlled transition from surface-dispersed distributions to monolayer patches with local hexagonal packing and tunable interparticle gaps. Quantitative gap statistics and Voronoi topology (via Delaunay analysis) show that thiol co‑stabilization yields the most uniform nearest‑neighbor separations and the highest degree of hexagonal coordination, whereas non‑thiol analogs produce broader gap distributions and increased disorder. These structurally distinct states directly correlate with optical response: as the mean inter-AuNP gap decreases, the ensemble localized surface plasmon resonance (LSPR) peaks at longer wavelengths with stronger intensity, which is consistent with coupling signatures and near‑field hybridization confirmed in the full-wave electrodynamic simulations. This work provides a general chemical handle for programming plasmonic lattices on curved soft templates.