Study On Morphology Control Of Silver Nanoparticles In SDBS/PVP Solution

Silver nanoparticle can be widely used in many crucial areas such as catalyst, optical materials, electronic slurry, electronic circuit, immunoassay, medical and biomedical applications, etc. because of their unique physical, chemical and mechanical properties. These peculiar and fascinating properties strongly depend on the particle size and shape, therefore the shape-controlled preparation of silver nanomaterials becomes very significance. Nowadays a great variety of effective chemical methods have been proven to prepare silver nanostructures with various morphologies, but the actual formation mechanism of silver nanostructures has not yet been fully revealed, which bring puzzles in mass production and still need further studies.In this paper, silver nanoparticles are reduced from silver nitrate by hydrate hydrazine, and it basically discusses the effect of sodium dodecyl benzene sulfonate (SDBS) polyvinyl and pyrrolidone (PVP) to the products. The structure of SDBS-Ag ligand is disscussed and the infections of different factors to the nanoparticles are preliminarily explored. Ultraviolet-visible spectrophotometer (UV-vis) and Fourier transform infrared spectrometer (FR-IR) are introduced to track the optical properties and microstructures of the reaction solution and intermediate products. The as-prepared particles are analyzed and characterized though scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).The results show that, the surface tension-concentration (γ-c) curves has dual critical concentration in sodium dodecyl benzene sulfonate (SDBS)-polyvinyl pyrrolidone (PVP) solution, which present as C1 (-2mmol/L) and C2 (-12mmol/L) respectively in 1.5% PVP solutions. Between the two-critical concentration, SDBS molecules assemble on the molecular chain of PVP to form certain "bound micelle", presenting as "pearl- necklace" structure. Moreover, the S-O in SDBS will coordinate the Ag as M-O-S complex, so as to construct the two-dimensional inorganic-organic layered structure, SO3-M-O3S as inorganic layer and alkyl chain as organic layer, and this layer structure would lead to the appearance of nano-silver plates; while the PVP molecules disperse and protect the as-prepared nanostructures through the electronic effect of the N, O atoms with Ag and through adsorption of PVP molecular chain.Moreover, Silver nanoparticles with plate structure can be formed in a large concentration range of Ag+(0.02 mol/L-1.5 mol/L) when the SDBS concentration is greater than 2mmol/L. The particle size distribution can be controlled though the adjustment of reaction time and stirring speeds. Comparatively, the effects of induction and dispersion of organic molecules are better in the solution that:the SDBS concentration of 8 mmol/L, the PVP concentration of 1.5%(wt%), the Ag+ concentration of 0.2 mol/L at room temperature. And the structures of the as-obtained products are uniformer.