Emulsion Polymerization in Coatings: DO’s and DON’Ts
Last update on Jun 12, 2017
Polymer emulsions can be defined as dispersions of polymeric particles in an aqueous dispersion media. They are polymer dispersions, by technical terms, and often referred to as 'emulsion polymers', 'dispersions' or 'polymer latex'.
The starting formulation is an emulsion of organic monomer in water. This is then stabilized by emulsifying agent(s), such as:
- Natural detergent
- Synthetic Detergent, or
- Polymeric colloid
The polymer particles are formed by means of free radical polymerization, which is started in the aqueous phase of the emulsion. The particle formation mechanism can be either micellar or non-micellar. This depends on water solubility of the monomer and the chemical nature of the emulsifier.
During the course of polymerization, the monomer transfers from the emulsified droplets into the growing polymer particles. Thus, the polymer dispersion is formed. The resulting product has about 50 - 60 % solid polymer content dispersed in aqueous phase. In the vast majority of their applications, the polymer dispersions are ready to use without further processing steps. But there are also cases where the polymer get precipitated and further processed in solid state.
Since its first industrial application in early 20th century, emulsion polymerization developed to be one of the most versatile polymerization techniques in polymers industry. Let's understand this technique in detail starting with its values.