Amphibious polymer-functionalized CdTe quantum dots: Synthesis, thermo-responsive self-assembly, and photoluminescent properties

Abstract

A straightforward strategy is presented to functionalize aqueous-phase synthesized CdTe quantum dots (QDs) with thermo-sensitive poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) via direct surface-initiated oxyanionic vinyl polymerization. The polymer grafting quantity can be facilely controlled in a wide range up to 95.2wt% by adjusting the weight feed ratio of monomer to pristine QDs. The polymer-grafted QDs still retain good fluorescence properties in solution, solid polymer matrix, and on surfaces of silica (SiO₂) sphere. The resulting QD@PDMAEMAs show excellent solubility both in water and organic solvents (e.g., chloroform, dichloromethane, dioxane, ethyl acetate, acetone, methanol, and N, N-dimethylformamide). We have called them amphibious QDs. The thermo-sensitive PDMAEMAs make QDs accessible to self-assemble reversibly by adjusting temperature when the grafted polymer content is over a certain value. The self-assembly process and resulting structure were demonstrated by TEM, variable temperature dynamic light scattering (DLS) and UV-vis spectrometer. Because PDMAEMA is a kind of positive polyelectrolyte, QD@PDMAEMAs were used as building blocks in the layer-by-layer self-assembly process on the surface of SiO₂ spheres, affording fluorescent SiO₂ spheres.