Layer-by-layer Assembly of Acrylate Copolymers and CdTe Nanoparticles

Mercaptoacetic acid-stabilized CdTe quantum dots (QDs) are prepared directly in aqueous solution. The multi-layer films of acrylate copolymer and CdTe nanoparticles were obtained by the layer-by-layer electrostatic self-assembly. It is shown that positively charged acrylate copolymer can be directly assembled outside the anionic CdTe QDs through an electrostatic force. The optical properties of the CdTe nanoparticles and the film build-up are monitored by employing the absorption and fluorescence spectroscopy. The deposition process is linearly related to the number of bi-layers as monitored by UV-vis absorption spectroscopy. The fluorescence intensity of ultrathin film rises with the DM content (9.69%, 16.29%, and 36.55%) in the acrylate copolymer and the photoluminescence spectra of multi-layers exhibit a red shift, indicating the enhancement of electrostatic forces between the carboxyl groups of thioglycolic acid capped on CdTe quantum dots and quaternization acrylate in cationic copolymer. The electrostatic interaction on the surface of the CdTe was enhanced with the DM content in the copolymer. Characterization of the multi-layer structures has been carried out by X-ray photoelectron spectroscopy. At the same time, the membrane morphology is investigated by atomic force microscopy. Electrostatic forces between anions in CdTe nanocrystals; and cations in the copolymer strengthen the stability of the inorganic/organic compound because it played the role of surface passivation in CdTe QDs.