Colloids are particles in the size range from about 10 nm to 10 µm, which are dispersed in a medium. Characteristic to them is that they are on one hand small enough to experience pronounced Brownian motion and on the other hand large enough to regard the surrounding medium as homogeneous.
In daily life we meet them in form of foods, paints or cosmetic products, however at our institute we preferentially investigate well defined spherical particles made out of polystyrene or other polymers. The properties of colloidal dispersions and emulsions result from microscopic interactions of colloidal particles among themselves and external boundaries.
Here we present some experiments and their results as well as an introduction to the fundamental techniques required to investigate these colloidal particles.