Site-Specific Chemistry on Gold Nanorods: Curvature-Guided Surface Dewetting and Supracolloidal Polymerization

Control of interparticle interactions in terms of theirdirectionand strength highly relies on the use of anisotropic ligand graftingon nanoparticle (NP) building blocks. We report a ligand deficiencyexchange strategy to achieve site-specific polymer grafting of goldnanorods (AuNRs). Patchy AuNRs with controllable surface coveragecan be obtained during ligand exchange with a hydrophobic polystyreneligand and an amphiphilic surfactant while adjusting the ligand concentration(C (PS)) and solvent condition (C (water) in dimethylformamide). At a low grafting densityof & LE;0.08 chains/nm(2), dumbbell-like AuNRs with twopolymer domains capped at the two ends can be synthesized throughsurface dewetting with a high purity of >94%. These site-specifically-modifiedAuNRs exhibit great colloidal stability in aqueous solution. Dumbbell-likeAuNRs can further undergo supracolloidal polymerization upon thermalannealing to form one-dimensional plasmon chains of AuNRs. Such supracolloidalpolymerization follows the temperature-solvent superpositionprinciple as revealed by kinetic studies. Using the copolymerizationof two AuNRs with different aspect ratios, we demonstrate the designof chain architectures by varying the reactivity of nanorod buildingblocks. Our results provide insights into the postsynthetic designof anisotropic NPs that potentially serve as units for polymer-guidedsupracolloidal self-assembly.