A Versatile Synthetic Approach to Covalent Binding of Polymer Brushes on CdSe/CdS Quantum Dots Surface: Multitype Modification of Nanocrystals

Abstract

A novel and versatile approach to the preparation of multitype polymers brushes on the quantum dots surface is reported. In this method, an azo initiator is fi rst immobilized covalently onto CdSe/CdS particle surface by reacting with the 4,4′-Azobis (4-cyanovaleric acid) through an ester linkage. CdSe/CdS nanoparticles with polymer brushes (CdSe/CdS-polymers) of different properties, including hydrophilic polyacrylamide, poly(acrylic acid), and poly(vinyl pyrrolidone); hydrophobic oleophilic poly(vinyl acetate), poly(methyl acrylate), and poly(methyl methacrylate); polystyrene with conjugate group; and polyacrylonitrile with strong polarity group, are synthesized by one approach (the surface-initiated radical poly merization technique), respectively. The structures and properties of CdSe/CdS-polymers reveal that the CdSe/CdS-azo initiator has excellent ability to initiate various kinds of vinyl monomers and these synthetic CdSe/CdS-polymers exhibit good stability and can emit multiple colors from the emission 405 to 569 nm. Moreover, CdSe/ CdS-polymers brushes show characteristic micromorphologies. Such strategy provides a platform to achieve nanocomposites with different properties by a new CdSe/CdS-azo initiator through the simple conventional radical polymerization technique. Besides, the synthetic approach gives access to multitype modifi cation of different nanoparticles with polymers.

Stability of Quantum Dots, Quantum Dot Films, and Quantum Dot Light‐Emitting Diodes for Display Applications

“…The high packing density of films led to lower oxygen and moisture permeability. Covalent bonding is one of the best ways to reduce the distance between polymers and this concept was attempted in QDs and the polymer matrices to enhance stability of QD films . The QD/silica matrix was suggested as a highly stable color conversion substance, which forms direct networking among the hydroxyl group terminated QDs and tetraethylorthorsilicate .…”

“…This QD/silica matrix showed the possibility of demonstrating white backlight for display by down conversion of the blue LED with the high photostability and optical efficiency. For the another example, the diazo groups, which could generate radicals with heat, were substituted as ligands on the QD surface and mixed with 8 kinds of monomers having vinyl or acrylate groups, respectively . Radical polymerization was initiated on the QD surface with the monomer and the reaction resulted the interconnected QD film by covalent bond between the QD and the monomer.…”

Responsive Polymer Brush Design and Emerging Applications for Nanotheranostics

“…[41,42] In contrast, the functionalization of polymer brushes from the surface of semiconductor particles such as quantum dots (QDs) can reduce the density of surface dangling bonds and defect levels, and improve the photoluminescence intensity and stability of the nanocrystals in aqueous media. [49] Using this approach, Lai et al [50] reported a novel and versatile method for the preparation of multitype polymer brushes from the surface of QDs, involving functionalization with an azo initiator onto the surface of QDs, followed by reaction with 4,4′-azobis (4-cyanovaleric acid) via an ester linkage.…”

Optically detected magnetic resonance study of relaxation/emission processes in the nanoparticle-polymer composite

“…Their transparency in the whole visible range and mechanical stability make them promising for optical applications [22][23][24][25][26]. Moreover, both polymers are bio-compatible and used for development of, e.g., drug-delivery and marker nanosystems, including the composites with semiconductor NPs [27,28].…”