Morphology-Dependent Chiroptical Switching in Intrinsically Chiral Gold Nanorods Encapsulated with Polyaniline.

Abstract

Exploring switching strategies for intrinsically chiral plasmonic nanoparticles is crucial for unlocking their potential in the dynamic manipulation of light polarization states. Conjugated polymers, such as polyaniline (PANI), represent highly promising material candidates for this pursuit, owing to their combination of intrinsic structural flexibility, tunable optical characteristics, and multistimuli responsiveness. Herein, we demonstrate chiroptical switching on PANI-encapsulated chiral gold nanorods (cAuNRs) by controlling proton doping of PANI, and reveal that the morphology of PANI within the nanogaps of cAuNRs results in abnormal spectral shifting, which is in contrast with those in previous studies. Moreover, we elucidate that the near-infrared absorption of doped PANI reduces the chiroptical response intensity, leading to splitting in the circular dichroism spectra. Our study provides valuable insights into the interaction between conjugated polymers and chiral plasmonic nanoparticles, supporting potential applications in nanoscale chiroptical switches for on-chip devices.