Solvent-Free Atom Transfer Radical Polymerization in the Synthesis of Fe₂O₃@Polystyrene Core−Shell Nanoparticles

This paper describes the use of solvent-free atom transfer radical polymerization (ATRP) in the synthesis of Fe 2 O 3 @polystyrene (PS) core−shell nanoparticles. In this approach, oleic acid stabilized Fe 2 O 3 nanoparticles were ligand exchanged with 2-bromo-2-methylpropionic acid (Br-MPA), the initiator for ATRP. These Fe 2 O 3 nanoparticles become soluble in styrene and can be used as macroinitiators for solvent-free ATRP. The synthesized core−shell nanoparticles were characterized by transmission electron microscopy (TEM), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), ultraviolet−visible (UV−vis) spectroscopy, and Fourier transform-infrared (FT-IR) spectroscopy. Well-defined Fe 2 O 3 @PS core−shell nanoparticles were obtained. The glassy transition temperature of PS was studied using DSC, and the molecular weight of PS was characterized by GPC. The unique aspects of this solvent-free ATRP in the synthesis of well-defined polymer-coated nanoparticles will be discussed.