Self-Assembly of Regioselective Polymer-Tethered Gold Nanorods in Selective Solvents

Abstract

The self-assembly of regioselective polymer-tethered gold nanorods (AuNRs) offers significant potential for creating functional nanoscale architectures with applications in optoelectronics, sensing, and nanomedicine. In this study, we synthesized AuNRs with well-defined dimensions and modified them regioselectively with polystyrene (PS) at the ends and poly(4-vinylpyridine) (P4VP) on the sidewalls. Controlled self-assembly was achieved using selective solvent methods, resulting in distinct end-to-end and side-by-side configurations depending on the solvent environment. The study further explored the influence of the molecular weight of the polymer ligands and the AuNR core size on the assembly structures. Additionally, the assembly process were investigated in real-time using small-angle X-ray scattering (SAXS) and UV–visible spectroscopy, revealing a two-stage assembly process significantly affected by solvent composition. The results demonstrated that the evaporation rate of the solvent plays a critical role in the final assembly morphology. Slow solvent evaporation led to the formation of well-ordered thin films due to the gradual aggregation of side-by-side arranged AuNRs, while faster evaporation favored the formation of vesicles or micelles. These structures are a result of the differential solubility and phase separation of the polymer ligands under varying solvent conditions. This study provides a comprehensive understanding of the assembly mechanisms and the dynamic processes governing the formation of different nanostructures, offering a foundation for the design of AuNR-based nanomaterials with precise structural and functional control.