Synthesis and characterization of nanosized metals embedded in polystyrene matrix

Thermal treatment of a solution containing iron pentacarbonyl and styrene monomer in hexadecane resulted in a high yield (>90%) of nanoparticles of iron encapsulated in a polystyrene matrix (Fe-PST). The freshly prepared off-colored Fe in polystyrene (Fe-PST) material consisted of black particles that were attributed to zero-valent iron. On exposure to air, the black Fe particles slowly turned dark brown due to conversion into iron oxide. The observed oxidation phenomenon was confirmed by electron paramagnetic resonance (EPR) spectroscopy: the freshly prepared Fe-PST was EPR silent but after exposure to air, a strong signature EPR signal for iron oxide was recorded. The infrared data confirmed changes in intensity of characteristic bands of PST in Fe-PST. The TEM image of the oxidized Fe-PST material consisted of discrete Fe particles that were distributed throughout the polymer matrix. The differential scanning calorimetric data of Fe-PST showed an enhanced glass transition temperature to 120 °C owing to the presence of Fe nanoparticles.