Synthesis and characterization of PbS nanoparticles in block copolymer micelles

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Abstract
Precipitation of lead ions by hydrogen sulfide in the presence of amphiphilic block copoloymer micelles composed of polystyrene‐b‐poly(4)vinylpridine yields PbS nanoparticles. By adjusting the reaction conditions with respect to the lead‐to‐polymer ratio, temperature or proton concentration particles of different size (2 to 20 nm) and morphology (spheres, cubes or needles) have been prepared. These particles have been characterized by powder X‐ray diffraction and High Resolution Transmission Electron Microscopy (HRTEM).At a low lead content of the polymer micelles and relevated temperatures the formation of nanocrystalline PbS needles is preferred. These exhibit a structured absorption spectrum with two peaks at 375 and 580 nm. In polymer micelles with high lead content, PbS spheres (1 to 2 nm) are formed. Growth of these particles can be induced by increasing the proton concentration, resulting in particles with diameters up to 20 nm.