document: From a general point of view, polymerization techniques can be divided into two types of chemical reactions: step-growth polymerization and free radical polymerization. Step-growth polymerization is widely used for synthesis of polyesters, polyamide and epoxies while the synthesis of polyacrylics requires the use of free radical polymerization. These polymerization reactions can be performed either in bulk or in solution or in dispersed media. Heterophase polymerizations (i.e. emulsion, dispersion and miniemulsion polymerizations) present the advantage of easier removal of the resulting product from the reactor compared to bulk polymerization thanks to the low viscosity of the reaction medium. Polymerization in solution also induces lower viscosity but also lower reaction rates due to dilution of the reactants and higher cost and environmental impact due to the use of organic solvents. These problems are solved in the case of heterophase polymerizations where the reactants are confined inside droplets (no dilution effect) and water is used as medium. The use of surfactant molecules are usually needed for the stabilization of the monomer droplet and subsequent polymer particles in the water phase.
extractive_keyphrases: bulk chemical reactions dilution dispersed media dispersion droplets emulsion epoxies free radical polymerization heterophase polymerizations miniemulsion polymerizations monomer droplet organic solvents polyacrylics polyamide polyesters polymerization polymer particles reactants reaction reactor removal of the resulting product solution surfactant molecules water
abstractive_keyphrases: bulk polymerization dilution effect polymerization reactions polymerization techniques reaction medium stabilization of the monomer droplet step-growth polymerization synthesis of polyacrylics synthesis of polyesters