Magnetic droplet

The binding capacity is essentially determined by the total specific surface of the magnetic droplets. Since this parameter must be controlled with great accuracy, monodisperse emulsions become necessary. 

M. Heidenreich, R. Kimmich 1999, (Magnetic-resonance determination of the spatial dependence of the droplet size distribution in the cream layer of oil-in-water emulsions Evidence for the effects of depletion flocculation) Phys. Rev. E 59, 874. 

A diamagnetic body such as a droplet of water has, by its very definition, negative magnetic susceptibility. In the presence of a magnetic field, a force acts on the body when the scale of the magnetic-field... 

In TFB technique, the thin film radius is typically of the order of 100 pm, far larger than the contact film radius likely to be formed when two micron-sized droplets approach. The magnetic chaining technique overcomes this limitation, allowing the direct measurement of force-distance profiles between liquid colloidal droplets. This technique exploits the properties of monodisperse ferrofluid... 

The repulsive force, F), between the droplets must exactly balance the attractive force, Fm, between the dipoles induced by the applied magnetic field. Since the dipoles are aligned parallel to the field, this force can be calculated exactly and is given by [16] ... 

Figure 7.1. (a) Transmission electron microscopy image of a collection of 200-nm magnetic emulsion droplets obtained from emulsifying an octane-based ferrofluid. (b) One droplet is shown after polymerization. A polymer shell is visible that encapsulates the iron oxide nanoparticles. (With permission of Ademtech). 

S.K. Mandal, N. Lequeux, B. Rotenberg, M. Tramier, J. FattaccioU, J. Bibette, andB. Dubertret Encapsulation of Magnetic and Fluorescent Nanoparticles in Emnlsion Droplets. Langmuir 21, 4175 (2005). 

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