Emulsion copolymerization. 2 - Mechanism and kinetics

Unlike homogeneous copolymerization, the same phenomenon taking place in emulsion is a very complex one; thermodynamic, kinetic and mechanistical aspects are to be taken into account. The present paper proposes a classification of monomer pairs related to their solubilities, which in turn, may be associated to the HLB value. The thermodynamic equations proposed by various authors are explained as a function of the nature of the monomer pair; moreover, the crucial role of the emulsifier is underlined with regard to solubility and stability. Monomer-polymer interactions are explained in terms similar to those of the Flory-Huggins theory. Special attention is given to monomer distribution between polymer particles, monomer drops and aqueous phase, respectively; this feature is of uttermost importance to calculate copolymer composition or copolymerization rate.