Suspension polymerization

In the suspension polymerization, the water-insoluble monomer is suspended in water. It is used an initiator which is preferably soluble in the monomer. The reaction then takes place in the monomer droplets. As a product usually obtained beads, therefore the term " suspension polymerization " in use.

Principle

First, the monomer is dispersed in water. In principle, it is at this time is an emulsion, which later turns into a suspension. Furthermore, initiator and protective colloids are added. The latter are intended to prevent the resulting monomer droplets coalesce and the suspension is separated. For this purpose are, for example, polyvinyl alcohol or barium sulfate used. The temperature is then brought to the reaction level. Finally, the polymer beads (diameter a few millimeters ) are separated and worked up.

The monomers must have a high purity, since the final polymer can no longer be cleaned. Copolymerization can be carried out also with this method.