SIZE CONTROL OF CDS QUANTUM-CONFINED ULTRAFINE PARTICLES BY PHOTOCATALYTIC POLYMER COATING

CdS quantum-confined ultrafine particles (Q-ufp) were prepared in coll oidal solutions in the presence of styrene monomer under photoirradiat ion. By means of transmission electron microscopy analysis, it has bee n experimentally verified for the first time that the prepared CdS Q-u fp were coated with polystyrene layer, and the particle size distribut ion was controlled by selecting the wavelength of the irradiating lase r light: shorter wavelength light irradiation gave smaller CdS Q-ufp. A mechanism for particle size control through photocatalytic polymer c oating is discussed to explain the experimental results; the particle size distribution or corresponding W-vis absorption spectra were simul ated using the proposed model. As a result, the oxidation potential of styrene monomer, relative to the highest occupied molecular orbital ( HOMO) or the top of the valence band of CdS Q-ufp which depends on the particle size, is important for electron transfer necessary for initi ating the polymer coating process.