Synthesis of Monodisperse CdS Nanospheres in an Inverse Microemulsion System Formed with a Dendritic Polyether Copolymer

Abstract

Nanosized CdS spheres with diameters of about 25, 40, and 50 nm have been synthesized in three inverse microemulsions formed with a dendritic amphiphilic copolymer (H2O/SD31/n‐butanol/n‐heptane) through the reaction of cadmium chloride (CdCl2) with the S2– ions that were slowly released from thioacetamide (TAA). X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis absorption and photoluminescence (PL) spectroscopy were used to characterize the CdS nanospheres obtained. TEM and XRD studies showed that monodisperse CdS nanospheres with the zinc blende structure were produced, and the size of the CdS spheres increased with increasing water‐core size because of the increasing [water]/[dendrimer] mass ratio (ω). The blue‐shift of the maxima in the UV/Vis absorption and PL spectra indicated that the CdS spheres consisted of primary CdS nanocrystals showing a quantum confinement effect. The viscosities of the three microemulsions were also determined by rheological measurements. The viscosity of the inverse microemulsion system decreased as ω increased. The water core of the inverse microemulsion provided a soft template for the precipitation of CdS spheres.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Nanostructures of Metal Tellurides (PbTe, CdTe, CoTe2, Bi2Te3, and Cu7Te4) with Various Morphologies: A General Solvothermal Synthesis and Optical Properties

“…It has been reported that the absorption of spherical nanoparticles of both metals and semiconductors can be enhanced and the absorption bands shift to short wavelengths at a smaller particle size. [34,35] It is known that CdTe is a semiconductor with a direct band gap (E g ) of 1.56 eV at 300 K. The intrinsic absorption occurs around 796 nm. [21] A similar result on CdTe nanowires dispersed in solution was recently reported by Liang et al [14] The as-prepared CdTe nanowires show an absorption in a wide range of wavelengths from about 280 to 800 nm (Figure 8b), which may be potentially useful for solar cell applications.…”

Non‐Volatile Organic Memory Applications Enabled by In Situ Synthesis of Gold Nanoparticles in a Self‐Assembled Block Copolymer

“…[7][8][9][10][11][12] The synthesis of nanoparticles in block copolymer micelles solves the problem of particle size control and stabilization compared to classical stabilization systems that employ surfactants [13][14][15] or microemulsions. [16,17] Nanocrystal-based organic memories [18][19][20][21] are attracting widespread interest owing to their simple structure and the prospect of creating 2D/3D stacks of these memory cells for increased bit densities. Recent reviews [20,22,28] summarize the literature for these nanoparticle-based organic memories comprehensively, and have identified the main operating mechanisms to be one of the following: (i) an electricfield-induced charge transfer between the nanoparticles and the surrounding conjugated compounds, [19,22] (ii) filamentary conduction, [23,24] (iii) charge trapping-detrapping, [25,26] and (iv) space-charge field inhibition of injection in the nanoparticles through a high-voltage pulse.…”

Comparison of the Surface Dilational Properties of Block Copolymers and Sodium Oleate Using the Oscillating Bubble Method

“…[34,35] Based on recent synthesis and investigation of a star-like block copolymer (AP432), [36] we report the oscillating bubble study in this paper aiming to investigate the correlation between the aggregation behavior in solutions and surface rheological parameters for AP432. In comparison, a linear PEO-PPO-PEO tri-block copolymer (Pluronic L64) which has similar PEO fraction to that of AP432 and an anionic surfactant sodium oleate (C 17 H 33 COONa) were also selected for study.…”