De l’évaporation des colloïdes magnétiques

Evaporation of so-called colloids, i.e. liquids containing (sub-)micrometric particles, is an omnipresent phenomenon. From the stain of coffee to the painting of our walls, via blood stains on crime scenes, the dried deposits they leave range from dirt to useful coating, via clues in criminal cases. The mechanisms behind the structuring of these deposits are then a topic of intensive research. Among recent proposals, magnetic colloids have been proposed as a model system. Indeed, their interactions can be controlled through an external magnetic field, acting as a remote control of the suspension properties. This paper reviews the most recent results regarding a specific subclass defined as superparamagnetic colloids. It has been written for a non-expert scientific audience. This review starts with a general introduction to the field of colloids evaporation, then describes the properties of superparamagnetic colloids. In its last sections, it offers an overview of the conditions in which a control of both the broad and detailed structures of superparamagnetic colloids evaporative deposits can be achieved.