Effect of chelating functional polymer on the size of CdS nanocluster formation

Abstract

Chelating poly(acrylates-co-2-methylacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester) microspheres of diameter 250–310 nm were prepared by the soap-free emulsion polymerization method for varying amounts of GMA-IDA. Then CdS/copolymer composite was generated by chemical deposition on the surface of the copolymer microspheres. By XRD analysis it is found that the chelated CdS nanoparticles are a pure cubic zinc blende structure. The CdS/copolymer composite is examined by UV–vis absorbance, photoluminescence, and TEM observation. Average CdS nanoparticle size calculated from Henglein's empirical curve is in the range of 3.0–8.0 nm and varies according to the GMA-IDA molar ratio during polymerization, pH value during chelation, and postchelation annealing temperature. Higher ratio of chelating group, pH value, and annealing temperature produce larger CdS nanoparticles. As GMA-IDA ratio increases, photoluminescence exhibits a red shift from 510 to 520 nm, photoluminescence increases, and bandwidth decreases. Photoluminescence of the CdS nanoparticle becomes negligible when diameter exceeds 5 nm.