Editing Emulsion polymerization (section)

===Initiators===
Both [[Heat|thermal]] and [[redox]] generation of free radicals have been used in emulsion polymerization. [[Persulfate]] salts are commonly used in both [[initiation (chemistry)|initiation]] modes. The persulfate ion readily breaks up into sulfate radical ions above about 50&nbsp;°C, providing a thermal source of initiation. Redox initiation takes place when an [[oxidant]] such as a persulfate salt, a [[reducing agent]] such as glucose, [[Rongalite]], or [[sulfite]], and a redox catalyst such as an iron compound are all included in the polymerization recipe. Redox recipes are not limited by temperature and are used for polymerizations that take place below 50&nbsp;°C.

Although organic [[peroxides]] and [[hydroperoxides]] are used in emulsion polymerization, initiators are usually water [[soluble]] and [[liquid-liquid extraction|partition]] into the water phase. This enables the particle generation behavior described in the theory section. In redox initiation, either the oxidant or the reducing agent (or both) must be water-soluble, but one component can be water-insoluble.