Emulsion polymerization basic principles

Working in emulsion is essentially limited to radical polymerization in water. Similar to suspension polymerization, the basic principle is to disperse a sparingly water-soluble monomer in water and bring about polymerization in this state. There are, however, some essential differences between the two procedures ... 

It was shown that the basic principle of mini-emulsion polymerization can be extended to the reaction systems stabilized by cationic and non-ionic emulsifiers, leading to a narrow particle size distribution [ 102]. Besides, the effect of the... 

The basic principle behind the preparation of a stable mini-emulsion lies in the decrease of solubility of monomer in the aqueous phase. This approach was applied to the fine emulsion polymerization and copolymerization of MMA, EA, nonyl methacrylate (NMA) and methacryloyl-terminated polyoxyethylene macromonomer (PEO-MA) initiated by UV light at room temperature by Capek [121,122]. At low temperature, the monomer droplet degradation is suppressed due to the lower water-solubility of monomer. Under these circumstances, the dependence of the rate of polymerization of MMA, EA or NMA is described by a curve with two maximal rates or four distinct non-stationary rate intervals, typical for the mini-emulsion polymerization. The effect of the restricted monomer droplets degradation is also considered as the result of accumulation of hy-... 

Polymerization reactors are a specific kind of chemical reactors in which polymerization reactions take place therefore, in principle, they can be analyzed following the same general rules applicable to any other chemical reactor. The basic components of a mathematical model for a chemical reactor are a reactor model and rate expressions for the chemical species that participate in the reactions. If the system is homogeneous (only one phase), these two basic components are pretty much what is needed on the other hand, for heterogeneous systems formed by several phases (emulsion or suspension polymerizations, systems with gaseous monomers, slurry reactors or fluidized bed reactors with solid catalysts, etc.), additional transport and/or thermodynamic models may be necessary to build a realistic mathematical representation of the system. In this section, to illustrate the basic principles and components needed, we restrict ourselves to the simplest case, that of homogeneous reactors in other sections, additional components and more complex cases are discussed. 

It can be seen from the above short discussion that agrochemical formulations are complex multiphase systems and their preparation, stabilization and subsequent application require the application of the basic principles of colloid and interface science and this is the objective of the present part [1, 2]. It will start with a section on surfactants and the physical properties of their solutions. This is followed by a section on the interfacial aspects of agrochemical formulations including adsorption of surfactants and polymeric surfactants at the air/liquid, liquid/liquid and solid/liquid interfaces. The stabilization of dispersions, both electrostatic and steric, is discussed in the next section. The basic principles of colloid and interface science are illustrated in detail by considering emulsion concentrates (EW s) and suspension concentrates (SC s). A summary will be given on microemulsions and controlied release of agrochemical formulations. 

Reactor configurations involved in continuous emulsion polymerization include stirred tank reactors, tubular reactors, pulsed packed reactors, Couett-Taylor vortex flow reactors, and a variety of combinations of these reactors. Some important operational techniques developed for continuous emulsion polymerization are the prereactor concept, start-up strategy, split feed method, and so on. The fundamental principles behind the continuous emulsion polymerizations carried out in the basic stirred tank reactor and tubular reactor, which serve as the building blocks for the reaction systems of commercial importance, are the major focus of this chapter. 

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