Synthesis and characterization of nanoscopic entities based on poly(caprolactone)-grafted cadmium sulfide nanoparticles

Nanosized CdS clusters have been synthesized using polyester chains with a thiol end group as a covalently attached colloidal stabilizer. Clusters were grown through the reaction of thiourea with cadmium acetate, which was in competition with surface stabilization due to the tethered poly(caprolactone) (PCL) chains. The kinetics of the CdS cluster growth in the presence of poly(caprolactone) ligands were compared with those obtained using a low molecular weight thiol. Control of the particle size was also achieved by varying the ratio of thiourea to PCL ligands. The resulting nanoscopic entities obtained in different solvents (DMF or THF), remained stable in solution for several months and could be cast into films. Homogeneous dispersions of CdS particles in a polymer matrix were obtained by solvent evaporation. The particle size and distribution were characterized using ultraviolet-visible and photoluminescence spectroscopies, and transmission electron microscopy.