Preparation and characterization of nanocrystalline PbSe in poly(acrylic acid- co -styrene)
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The in situ reduction method was used to prepare nanocrystalline PbSe in a poly(acrylic acid-co-styrene) matrix. Metal precursor-doped polymer film was treated with selenium and reducing reagent (NaBH4) in ethylenediamine, leading to the formation of assemblies of crystalline semiconductive PbSe in polymer. The preparation was done at room temperature and ambient pressure. X-ray diffraction, x-ray photoelectron spectroscopy, infrared, scanning electron microscopy, transmission electron microscopy, and ultraviolet-visible spectra were used to characterize the as-prepared materials. The key factor for successful preparation of this composite was also discussed.
I. INTRODUCTION
Much recent effort has been directed toward the fabrication of polymers containing nanometer-sized particles of inorganic semiconductors.1–8 They are of considerable interest and importance since they may possess properties that are optimal combinations of those of the separate organic and inorganic components. In addition, some composites may exhibit properties that are totally absent in each of the components. Metal chalcogenides/polymer nanocomposites are considered to be highly functional materials to be used as photoluminescent,9 electroluminescent,10 and nonlinear optical materials.11 The flexibility and processability of polymer matrices can provide good mechanical properties. Recently, many techniques such as the element direct reaction method,12,13 exchange reaction of organometallic reagents in solvent,14,15 hydrothermal route at elevated temperature and pressure,15 and chemical bath deposition16,17 have been developed to synthesize inorganic semiconductors. Almost all methods need rigorous conditions, complex reagents, and a complicated process in synthesizing the selenides. Though many new methods have been used to prepare sulfide/polymer nanocomposites, relevant reports on selenide/polymer nanocomposites are limited. In general, two basic routes have been used to synthesize sulfide/polymer composites.18–23 One is to conduct the inorganic reaction between metal ion sources with H2S or organometallic sulfur sources inside the polymer matrix, and the other is to polymerize the a)
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J. Mater. Res., Vol. 16, No. 10, Oct 2001 Downloaded: 19 Mar 2015
monomer doped with the inorganic semiconductor components. But because of the reasons mentioned above, selenide/polymer composites have to be prepared via a two-stage process.9,10,24 First, one must synthesize the selenide nanocrystals and polymer separately and then disperse the selenide into the polymer. There is not a convenient way to get this composite directly. Though using the chemical bath deposition method can deposit a thin selenide layer on the polymer surface, the interaction force between the selenide layer and the polymer matrix is very weak and the selenide can be easily removed from the matrix. So this method is not available to achieve steady selenide/polymer compo
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