Water-based synthesis of ZnSe nanostructures using amphiphilic block copolymer stabilized lyotropic liquid crystals as templates

Simultaneous size and shape control of zinc selenide (ZnSe) nanostructures was achieved using lyotropic liquid crystal templates formed by the self-assembly of an amphiphilic block copolymer in the presence of water and a less polar organic solvent. ZnSe quantum dots, hollow nanospheres, nanotubes, and nanolaminates (parallel nanoplates or free-standing quantum wells) were grown at room temperature in the aqueous phase of a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) block copolymer/water/p-xylene ternary system. The nucleation of ZnSe was facilitated by an irreversible reaction between zinc acetate dissolved in water and hydrogen selenide gas that was allowed to diffuse into the self-assembled template. The nanostructures exhibit good crystallinity under high-resolution transmission electron miscroscopy and quantum confinement effects in their photoluminescence spectra. The shape and size of nanocrystals can be precisely controlled by altering the structure of the templating phase, by tuning the size of the nanodomains, and by changing the concentration of the zinc precursor.

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