Studying Of Polymer/Semiconductor Nanocrystals Composites In Aqueous Solution

As a kind of very important photoelectric material, CdS and CdSe nanoparticles have drawn more attention recently. Because of its potential applications, a variety of synthesis schemes have been developed.In the dissertation, CdS nanocrystals were prepared in aqueous solution with water-soluble polymer PVP(polyvinylpyrrolidone) and PSM(styrene-maleic anhydride copolymer) as stabilizer. Besides, water soluble CdSe nanocrystals were coated with PAM(polyacrylamide) by w/o microemulsion. AFM and TEM were utilized to study the morphology shape. The structure was characterized by means of XRD. Uv-vis and PL spectra were used to study optical property. Finally, FT-IR was utilized to study the interaction between polymers and nanocrystals.1. In the presence of PVP, it was found that through adjusting the pH values of aqueous solution or PVP concentrations, the morphology of CdS nanoparticles would be transformed from spherical to clubbed shape. Spherical CdS nanopartilces have good shape and size distribution. Furthermore, the effect of thioacetic acid on the optical property of CdS nanoparticles was discussed.2. Using PSM copolymer as template, CdS nanoparticles got by this method show smaller particle size and more well-proportioned size distribution. The result indicates that there are some interaction between CdS and maleic anhydride, and CdS/polymer nanocrystal composites were very stable and gave much brighter photoluminescence when the solution is in big pH value.3. Using thioacetic acid as surface modifier, water soluble CdSe nanocrystals were made in aqueous solution. Size and size distribution and optical properties of CdSe nanocrystals were also studied in this chapter for next coating.4. By using w/o emulsion system, CdSe nanoparticles were encapsulated by PAM which meanwhile was polymerized with AM monomer in water droplet. AFM indicated that core/shell CdSe/PAM nanoparticle composites have the diameter about 70nm.