Synthesis of nanocrystal - Polymer transparent hybrids via polyurethane matrix grafted onto functionalized CdS nanocrystals

We reported the first synthesis of CdS nanocrystal - polymer transparent hybrids by using polyurethane (PU) grafted onto quantum dots (QDs) CdS nanocrystals. In a typical run, the appropriate amounts of cadmium chloride (CdCl₂) and sodium sulfide (Na₂S) in the presence of 2-mercaptoethanol (ME) as the organic ligand are well dispersed in H ₂O/DMF solution without any aggregation. From a combination of transmission electron microscopy (TEM) and a computing method of Brus's model according to UV - vis absorption spectra, the particle size of as-prepared hydroxyl-coated CdS nanocrystals is about 5 nm. Then, PU - CdS transparent nanocomposites hybrids were synthesized by a two-step reaction. The effect of the different ratios of ME/Cd²⁺ and H₂O/DMF on the resulting particle size of CdS nanocrystals was investigated by UV - vis absorption measurements. FT-IR and TGA characterizations indicate the formation of robust bonding between CdS nanocrystals and the organic ligand. The fluorescence measurement shows that CdS - PU hybrids exhibit good optical properties.