Anchoring Silver with Poly(vinylidene fluoride) Molecules in Model Flocculates and Its Effects on Rheology in Stable Nanofluids
Sonicating a hot solution of silver nitrate and in-situ dynamic coating of a polymer of poly(vinylidene fluoride) (PVF2) molecules on the resulting silver of nanoparticles (NPs) in N,N-dimethyl formamide (DMF) give a stable nanofluid. The PVF2 moieties bond on the Ag-NPs and lead to cross-link the later in a specific assembly that determine rheology and associated properties. Uniquely, a nanofluid gives a yield stress as largely as 9.1 Nm–2 with an induced shear stress ∼1.5 Pa (at γ = 100 s–1 shear rate) when the Ag-NPs with a critical dosage 0.3 wt% bridge a dispersed structure over the carriers of an optimal 30 g/L PVF2 in DMF at room temperature. A grafted carrier liquid of DMF with PVF2 carries over the Ag-NPs suspended within it easily until a limit ≤ 5.0 wt% in small assemblies. Following a Non-Newtonian behavior, the shear stress increases linearly over γ ≤ 60 s–1, with a slope 0.60 Pa · s, unless a shear thinning dominates (> 0.3 wt% Ag-NPs). At very small ∼0.1 s–1, the viscosity traces two peaks well-separated apart at ∼0.2 and 0.5 wt% Ag-NPs (5 to 20 nm size) in a bimodal distribution of the flocculates via PVF2. From the HRTEM images, average hydrodynamic diameter in the DLS, and local vibration bands, a model cross-linked structure delineates how the microscopic interactions can be varied with effective size, shape, and number density in the flocculates useful for biological probes and other applications.
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Document Type: Research Article
Publication date: December 1, 2013
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- Journal of Nanofluids (JON) is an international multidisciplinary peer-reviewed journal covering a wide range of research topics in the field of nanofluids and fluid science. It is an ideal and unique reference source for scientists and engineers working in this important and emerging research field of science, engineering and technology. The journal publishes full research papers, review articles with author's photo and short biography, and communications of important new findings encompassing the fundamental and applied research in all aspects of science and engineering of nanofluids and fluid science related developing technologies.
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