Stable aqueous colloids of ZnS quantum dots prepared using double hydrophilic block copolymers

作者：Tarasov Konstantin; Houssein Dania; Destarac Mathias; Marcotte Nathalie; Gerardin Corine^*; Tichit Didier

来源：New Journal of Chemistry, 2013, 37(2): 508-514.

DOI：10.1039/c2nj40738h

Stable aqueous colloids of ZnS nanoparticles have been synthesised using zinc acetate, sodium sulfide and asymmetric double hydrophilic block copolymers PAA-b-PAM (polyacrylic acid-block-polyacrylamide) with various block molecular weights: M-PAA = 1000, 3000, 5000 g mol(-1) and M-PAM = 10 000, 15 000, 30 000 g mol(-1), respectively. The synthesis involves the formation of precursor hybrid polyion complex (HPIC) micelles, in which the micelle core is composed of Zn2+ ions complexed by polyacrylate blocks, while the corona is constituted by the stabilising neutral PAM blocks. The addition of S2- ions in the micelle solutions yields ZnS nanoparticles with a diameter of 3-4 nm. The ZnS nanoparticle size is weakly dependent on the copolymer block length, while the particle size distribution correlates with the copolymer asymmetry degree in such a way that a higher M-PAM/M-PAA ratio yields particles with a narrower size distribution. Characterisation by XRD and SEAD revealed that ZnS has a cubic sphalerite structure with the cell parameter a = 5.25 +/- 0.05 angstrom that is smaller than that of the bulk material (a = 5.406 +/- 0.05 angstrom). The obtained colloids present photoluminescent properties with an emission band peaking at 410 nm and exhibit a blue-shift of the band-gap energy in the UV-visible absorption spectra due to the quantum-confinement effect.

• 出版日期2013