Uniform polystyrene microspheres decorated with noble metal nanoparticles formed without using extra reducing agent

Uniform polystyrene (PS) spheres having various sizes from 60 to 1100 nm could be tailored by means of the surfactant-free emulsion polymerization based on styrene/potassium persulfate/water (St/KPS/H₂O) system. These PS spheres can intrinsically exhibit excellent dispersion property owing to their exterior sulfate groups. The Zeta potential measured can originally reach a value of -48 mV for the microspheres with size of 230 nm. By measuring in sodium chloride aqueous solution of 0.07 M, it was found to be greatly enhanced as high as -122 mV. Nano-dot-decorated metal-polystyrene composites could be achieved by a simple wet process in which metal ions such as gold (Au), silver (Ag) and palladium (Pd) were successfully performed metal deposition without any extra reducing agent. We found that the particle sizes of the metal dots deposited onto the surfaces of PS spheres are ranged from 5 to 10 nm. Images of high-resolution transmission electron microscopy and electron diffraction pattern having lattice constant of 2.35 Å revealed that the microstructure of gold (Au) particles anchored onto PS spheres could be fcc nanostructure.