Abstract:
A highly efficient and simple method for preparing small-size Janus gold nanoparticles (AuNPs) capable of self-assembling was developed. Firstly, the asymmetric star polymers ((LA)
7-CD-(PNIPAM
46)
14) were fabricated based on
β-cyclodextrin (
β-CD) by combining atom transfer radical polymerization (ATRP) and click chemistry. Secondary, the hydroxyl groups on the wide cross-section of the
β-CD molecule were modified to be ATRP initiator moieties, which then initiated the polymerization of
N-isopropyl acrylamide (NIPAM) to form fourteen PNIPAM chains via ATRP. The primary hydroxyl groups on the narrow cross-section of the
β-CD molecule were converted into azide groups and then coupled with 5-(1,2-dithiolan-3-yl)-
N-(prop-2-ynyl) pentanamide molecules by click chemistry. The obtained asymmetric star polymers ((LA)
7-CD-(PNIPAM
46)
14) were used to modify AuNPs that were formerly surface-stabilized by
n-butylthiol through the ligand exchange process. Due to the steric effect of (LA)
7-CD-(PNIPAM
46)
14 macromolecules, Janus hybrid AuNPs, Au
3.1-CD-(PNIPAM
46)
14, with amphiphilic surface were prepared, which could self-assemble in water into micelle-like aggregates, i.e. supermicelles. The chemical and chain structures of asymmetric (LA)
7-CD-(PNIPAM
46)
14 star polymers and the amphiphilic Janus hybrid Au
3.1-CD-(PNIPAM
46)
14 nanoparticles were characterized by Nuclear Magnetic Resonance (NMR), Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS), Gel Permeation Chromatography (GPC) and Thermal Gravimetric (TG) analysis. The morphology and structure of the prepared micelle-like self-assemblies were investigated by Transmission Electron Microscope (TEM).