Polyurethane-based bulk nanocomposites from 1-thioglycerol-stabilized CdTe quantum dots with enhanced luminescence

Abstract

1-Thioglycerol (TG)-stabilized quantum dots (QDs) are good candidate for performing a stepwise polymerization reaction with polyurethane (PU) prepolymers, but their use is limited by their worse photoluminescence (PL) in comparison to QDs stabilized by other mercapto-ligands. To overcome this problem, TG-stabilized CdTe QDs with enhanced PL were synthesized in water through a N₂H₄-promoted growth approach. The current synthesis significantly shortened the duration of the size evolution of QDs, particularly for obtaining samples with orange and red emissions. It also permitted QD growth at low temperatures, such as room temperature, which avoided the decomposition of TG and subsequent embedment of sulfur into the QDs as occurs in the conventional synthesis. Most importantly, the TG ligand endowed the QDs with hydroxyl coverage, making the QDs miscible with PU prepolymers in dimethyl sulfoxide, and therefore overcoming the main problem in fabricating PU-based nanocomposites of eliminating water. The hydroxyl coverage further allowed for the linkage of PU on the surface of the QDs through the reaction between –OH and –NCO, producing CdTe QD–PU bulk nanocomposites. Systematic characterization indicated that the QDs were well dispersed in the PU medium, and the size-dependent PL of QDs was also maintained.