Precipitation, stabilization and molecular modeling of ZnS nanoparticles in the presence of cetyltrimethylammonium bromide

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• 作者：Petr Praus^a ; ^{petr.praus@vsb.cz} ; Richard Dvorský ; ^b ; Petra Horí ; nková ; ^a ; Miroslav Pospí ; &scaron ; il^c ; Petr Ková ; 艡^c
• 关键词：ZnS nanoparticles ; Cetyltrimethylammonium bromide ; Molecular modeling
• 刊名：Journal of Colloid and Interface Science
• 出版年：2012
• 期刊代码：125_00219797
• 类别：ch
• 出版时间：1 July, 2012
• 卷：377
• 期：1
• 页码：58-63
• 文件大小：469 K

摘要

ZnS nanoparticles were precipitated in aqueous dispersions of cationic surfactant cetyltrimethylammonium bromide (CTAB). The sphere radii of ZnS nanoparticles calculated by using band-gap energies steeply decreased from 4.5 nm to 2.2 nm within CTAB concentrations of 0.4-1.5 mmol L^鈭?. Above the concentration of 1.5 mmol L^鈭?, the radii were stabilized at R = 2.0 nm and increased up to R = 2.5 nm after 24 h. The hydrodynamic diameters of CTAB-ZnS structures observed by the dynamic light scattering (DLS) method ranged from 130 nm to 23 nm depending on CTAB concentrations of 0.5-1.5 mmol L^鈭?. The complex structures were observed by transmission electron microscopy (TEM). At the higher CTAB concentrations, ZnS nanoparticles were surrounded by CTA⁺ bilayers forming positively charged micelles with the diameter of 10 nm. The positive zeta-potentials of the micelles and their agglomerates were from 16 mV to 33 mV.

Wurtzite and sphalerite nanoparticles with R = 2.0 nm and 2.5 nm covered by CTA⁺ were modeled with and without water. Calculated sublimation energies confirmed that a bilayer arrangement of CTA⁺ on the ZnS nanoparticles was preferred to a monolayer.