Spherical Assemblies of Semiconductor Nanoparticles in Water-Soluble Block Copolymer Aggregates

Abstract

Novel spherical assemblies of CdS-containing block copolymer reverse micelles in aqueous solution have been formed by the slow addition of water to mixtures of the reverse micelles and a polystyrene-b-poly(acrylic acid) stabilizer. The structures are large compound micelles (LCMs) with quantum-confined CdS nanoparticles dispersed throughout a spherical PS matrix, which is stabilized in water by a layer of solubilized hydrophilic chains. The size of the CdS particles (2R CdS ∼ 3 nm) is controlled by the ionic block length, N B, of the block copolymer making up the reverse micelle. LCM formation is found to be dependent on the amount of added stabilizing copolymer. When the weight of stabilizer relative to the total polymer weight is 12% for the specific system under study, a single population of LCMs is formed (D ave = 64 nm); each of these LCMs consists of an average of 58 reverse micelles and 87 stabilizing chains, with an average surface area per stabilizing chain of 148 nm. At 10% stabilizer, two LCM populations, D ave = 52 nm and D ave = 152 nm, are formed. When the concentration of stabilizing copolymer is increased to 21 and 35%, regular micelles with no internal structure coexist with LCMs. Without added stabilizing copolymer, most reverse micelles undergo macroscopic precipitation upon water addition, although some LCMs are observed in the remaining solution.

From Hybrid Microgels to Photonic Crystals

“…5.2, 4.8, and 4.7 nm were found for the microgels with u 0.11, 0.22, and 0.44, respectively. [13,14] This estimation agreed with the results obtained by image analysis of the TEM images. The reduction in average dimensions of the CdS NPs formed in the poly(NIPAM-AA-HEA) microgels with increase of u indicated that spatial localization of Cd 2+ ions on COO ± groups of PAA hindered nanoparticle growth.…”

Thiophenol‐Modified CdS Nanoparticles Enhance the Luminescence of Benzoxyl Dendron‐ Substituted Polyfluorene Copolymers

“…From the absorption edge (k e ) in their UV-vis spectra, the S-CdS nanoparticles were determined to have diameters of ca. 3, 4, and 7 nm [34,35].…”

Surface-Modified Quantum Dots Enhanced Luminescence Polymer Nanocomposites Light Emitting Diode

“…3, 4, and 7 nm. [34][35] The synthesis of the dendritic polyfluorene was performed using a typical Suzuki coupling reaction protocol. The copolymerization of dendritic monomers and 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-dioctylfluorene was 16 performed using Pd(PPh 3 ) 4 as a catalyst and Aliquat 336 as a phase-transfer reagent in a mixture of toluene and aqueous potassium carbonate (2.0 M).…”