Preparation and characterization of CdS quantum dots chitosan biocomposite

In this paper biopolymer chitosan was used as a matrix to fabricate cadmium sulfide (CdS) quantum dots (QDs) with a narrow size distribution under mild conditions, resulting in a novel QDs biocomposite., The US QDs, whose size can be controlled by varying the reaction time and precursor concentration, were characterized by TEM and XRD. The limitation on US particle growth and agglomeration by chitosan was suggested by UV-vis spectrum and TEM results. FFIR-attenuated total reflectance (ATR) revealed strong hydrogen bonding between the US QDs and chitosan via N2 and O3 groups. This interaction was also reflected in AFM, XRD and swelling study results. The chitosan-capped US QDs exhibited improved aqueous solubility and stability. On the other hand, in the presence of CdS QDs, the thermal decomposition of chitosan was shifted toward a higher temperature by about 50 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.