Synthesis of Novel Amphiphilic Fluorinated Polymers for the Dispersion of Hydrophobic Gold Nanoparticles, Quantum Dots, or Highly Fluorinated Molecules in Water

The transfer of inorganic nanoparticles (NPs) into water is usually considered a challenge, as NPs are preferably synthesized in organic solvents and commonly bear hydrophobic ligands. Consequently, various methods have been reported to achieve their transfer to aqueous media. Among these, a polymer coating using amphiphilic polymers represents a particularly useful approach. These polymers can interact with the NP surface via their hydrophobic moieties, while their hydrophilic side remains exposed to the aqueous media, thus enabling dispersion in water. In this paper, we present the facile synthesis of several fluorinated, hydrosoluble amphiphilic polymers, and we study the coating of different types of metallic NPs, such as gold nanoparticles and quantum dots (QDs). Gold NPs were transferred via a phase transfer protocol, but for more sensitive QDs, we used the film hydration method. For QDs, the high hydrophobicity of fluorinated moieties on the polymer was particularly advantageous in repelling water and preserving the optical properties of QDs. Fractal arrangements in aqueous solution for polymer-coated QDs were analyzed by small-angle X-ray scattering (SAXS) but also observed by TEM. Additionally, we employed these fluorinated polymers to transfer two highly hydrophobic and fluorinated molecules (PERFECTA and PFCE), commonly used as contrast agents in ¹⁹F magnetic resonance imaging (¹⁹F MRI), into aqueous media. We evaluated their transverse and longitudinal relaxation times to assess their suitability for use as contrast agents for ¹⁹F MRI.