Spin-coating of moderately concentrated superparamagnetic colloids in different magnetic field configurations
| Autor: | Raheema Aslam, Wenceslao González-Viñas |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Spin coating
Materials science Flow (psychology) FOS: Physical sciences Nanotechnology 02 engineering and technology Condensed Matter - Soft Condensed Matter equipment and supplies 021001 nanoscience & nanotechnology 01 natural sciences 010305 fluids & plasmas Magnetic field Viscosity Colloid chemistry.chemical_compound Colloid and Surface Chemistry chemistry Chemical physics 0103 physical sciences Magnetorheological fluid Soft Condensed Matter (cond-mat.soft) 0210 nano-technology human activities Superparamagnetism Magnetite |
| Zdroj: | Colloids and Surfaces A: Physicochemical and Engineering Aspects. 532:530-534 |
| ISSN: | 0927-7757 |
| DOI: | 10.1016/j.colsurfa.2017.04.007 |
| Popis: | Spin-coating technique is very fast, cheap, reproducible, simple and needs less material to fabricate films of particulate systems/colloids. Their thickness and uniformity may be controlled by means of external fields. We apply magnetic fields during the spin-coating of a moderately concentrated superparamagnetic colloid (made of silica coated magnetite particles). We study the influence of different magnetic field configurations (homogeneous and inhomogeneous) on the resulting spin-coated deposits and compare experimental results under various conditions. Superparamagnetic colloids behave as, non-Newtonian, magnetorheological fluids. Their viscosity vary significantly under applied magnetic fields. We measure and compare the effect of uniform and non-uniform magnetic fields on their relative effective viscosity, using the spin-coated deposits and a previously existing model for simple colloids. The mechanisms involved in the deposits formation under different experimental conditions are also discussed. In particular, we show that the magnetophoretic effect plays an important role in the spin-coating of magnetic colloids subjected to non-uniform magnetic fields. We characterize an effective magnetoviscosity in non-uniform magnetic fields that is largely influenced by the magnetophoretic effect that enhances the flow of the magnetic fluid. Comment: Accepted for publication in Colloids Surf. A |
| Databáze: | OpenAIRE |
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