Synthesi Of Polyamidoamine Dendrimer And The Preparation Of CdS/Polyamidoamine Dendrimer Nanocomposite

Dendrimers, which have hyperbranched, well defined and monodisperse structures, can be formed by reiterative reaction sequences starting from smaller molecules named "initiator core". And their molecular weight, size, shape and functional group over surface can be controlled by the reactions and synthetic building blocks. Great attention has been paid to dendrimers in many fields, such as DNA delivery, catalyzer, Molecular Self-Assembly, et al.A series of polyamidoamine (PAMAM) dendrimers were prepared, with aniline in the core through repetitive Michael addition and amidation. Their structures were characterized by ¹H NMR, FT-IR and ESI-TOF. The results showed that PAMAM dendrimers with perfect structure were prepared from 0. 5 generation to 3.5 generation. Defect in structure was found in the preparation of the 4th generation, and the obtained main product was analyzed.Well-dispersed CdS quantum dots (QDs) with narrow size-distribution were prepared using generation 4.0 amine-terminated PAMAM dendrimers as inner-templates. A series of CdS/PAMAM dendrimer nanocomposites of different diameters were prepared by leading NaS into the methanol solution of Cd²⁺/PAMAM complexes with different Cd²⁺/PAMAM ratio. The obtained CdS/PAMAM nanocomposites were characterized by UV-Vis and photoluminescence spectrophotometry. The stability, diameter and dispersion of the CdS clusters were affected remarkably by the ratio of Cd²⁺ to G4.0 PAMAM dendrimer and solvent. The results showed that the better dispersion of CdS/PAMAM nanocomposites and the larger diameters were obtained in glycerine than that in methanol. The gained CdS/PAMAM dendrimer nanocomposites were characterized by UV-Vis spectrophotometry and TEM.