Synthesis of luminescent and rodlike CdS nanocrystals dispersed in polymer templates

A simple synthetic route for the preparation of luminescent and rodlike US nanocrystals embedded in poly (BA-co-GMA-co-GMA-IDA) (PBGM) copolymer templates, by soap-free emulsion copolymerization, is presented. In this study, GMA-IDA chelating groups within the copolymer were the coordination sites for chelating Cd2+ at which nanosized CdS nanocrystals were grown by the dry method (H2S) and the wet method (Na2S). The particle size and morphology of US nanocrystals were observed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). TEM observations demonstrate that the mean diameters of US nanoparticles can be prepared between I and 2 nm inside the matrix of PBGM membranes by the dry method and between 3 and 6 nm by the wet method. AFM images reveal that US nanocrystals on the surfaces of PBGM membranes formed by the dry method have rodlike morphology. The optical absorption spectra indicate a clear blue-shift in the absorption edge for the PBGM-CdS membranes, such that the bandgaps calculated from the absorption spectra are higher than those calculated for the bulk CdS. The particle sizes, estimated from the bandgaps, are in the nanometre range, suggesting that both the particle size and the bandgap can be adjusted via the mole fraction of GMA-IDA in the PBGM membranes. Luminescence spectrophotometry of the samples also indicates a blue-shift in the emission spectra.