Programmable Patch Formation on Anisotropic Nanoparticles

Polymer-grafted patchy nanoparticles on anisotropic inorganic cores provide a versatile platform for encoding directional interactions, spatially resolved chemistry, and adaptive interfaces, whereas isotropic nanospheres usually present nearly uniform shells to polymers, anisotropic cores such as rods, triangles, and polyhedra present tips, edges, and facets with distinct curvatures and coordination environments, which confine and solvate the grafted polymers at specific positions. This review discusses the translation of anisotropy into selective patch formation and the rational control of patch topology. We first discuss ligand-mediated strategies through which the preformed core surface is prepatterned by competitive adsorption, lateral-phase segregation, or facet-selective masking, creating polymer patches on an inhomogeneous ligand landscape. This section focuses on curvature-guided dewetting on gold nanorods, ligand island formation on nanotriangles, and halide-based atomic stenciling on polyhedral gold nanocrystals. We then examine routes through which initially uniform or weakly modulated homopolymer and block copolymer shells reorganize into discrete domains in response to changes in solvent quality or temperature, specifically solvent-triggered collapse into surface-attached micelles and heat-driven contraction and curvature-sensitive redistribution of grafted layers. Finally, we highlight exploitations of these mechanisms in representative anisotropic-reliant applications, including patch-programmed supracolloidal architectures, directionally coupled plasmonic assemblies, and anisotropic-reaction masks and adaptive coatings on rods and polyhedra. Overall, the review connects ligand chemistry, curvature, and external stimuli to the pathways of patch formation, outlining design principles of polymer-patched anisotropic nanoparticles as programmable building blocks for advanced hybrid materials.