Miniemulsion Polymerization Mechanisms and Kinetics

Moreover the miniemulsion, microemulsion and conventional emulsion polymerizations techniques show quite different particle nucleation and growth mechanisms and kinetics [271]... 

The influence of the type of initiators (sodium persulfate versus 2,2 -azobisisobutyronitrUe) on the particle nucleation mechanisms and kinetics involved in the styrene miniemulsion polymerizations has also been studied [39]. As expected, the oil-soluble 2,2 -azobisisobutyronitrile promotes nucleation in the homogenized monomer droplets. On the other hand, formation of particle nuclei in the continuous aqueous phase becomes more important when water-soluble sodium persulfate is used. This result is consistent with the vinyl chloride work of Saethre et al. [44]. The number of polyvinyl chloride latex particles generated by mechanisms other than monomer droplet... 

Dausend J, Musyanovych A, Dass M, et al. (2008) Uptake mechanism of oppositely charged fluorescent nanoparticles in HeLa cells. Macromol Biosci 8 1135-1143 Ziegler A, Landfester K, Musyanovych A (2009) Synthesis of phosphonate-functionalized polystyrene and poly(methyl methacrylate) particles and their kinetic behavior in miniemulsion polymerization. Colloid Polym Sci. http //dx.doi.Org/10.1007/s00396-009-2087-z Lorenz MR, Kohnle MV, Dass M, et al. (2008) Synthesis of fluorescent polyisoprene nanoparticles and their uptake into various cells. Macromol Biosci 8 711-727... 

Recently, several reviews have been written detaihng miniemulsion systems, with attention focused on the kinetics of miniemulsion polymerization [1, 2], the structure of the obtained nanoparticles [3], and their applications in medicine [4] and for catalysis [5]. As a consequence of the mechanism of miniemulsion s formation, and on the basis of their colloidal properties and stability, a wide range of different, industrially relevant polymers colloids can be generated using different types of polymerizations. Examples that have been reported in miniemulsions include polystyrene (first reported in 1973 [6]) or poly(vinyl chloride) (in 1984) [7] by radical polymerization sihcone (in 1994) [8] or polyamide (in 2005) [9] by anionic polymerization polyethylene (in 2000) [10] by catalytic polymerization epoxies (in... 

Heterophase polymerization systems can be defined as two-phase systems in which the resulting polymer and/or starting monomer are in the form of a fine dispersion in an immiscible liquid medium defined as the polymerization medium , continuous phase , or outer phase . Even if oil-in-water (o/w) systems are greatly preferred on an industrial scale, water-in-oil (w/o) systems may also be envisaged for specific purposes. Heterogeneous polymerization processes can be classified as suspension, dispersion, precipitation, emulsion, or miniemulsion techniques according to interdependent criteria which are the initial state of the polymerization mixture, the kinetics of polymerization, the mechanism of particle formation and the size and shape of the final polymer particles (Fig. 4.2) [18]. 

In the second chapter (Preparation of polymer-based nanomaterials), we summarize and discuss the literature data concerning of polymer and polymer particle preparations. This includes the description of mechanism of the radical polymerization of unsaturated monomers by which polymer (latexes) dispersions are generated. The mechanism of polymer particles (latexes) formation is both a science and an art. A science is expressed by the kinetic processes of the free radical-initiated polymerization of unsaturated monomers in the multiphase systems. It is an art in that way that the recipes containing monomer, water, emulsifier, initiator and additives give rise to the polymer particles with the different shapes, sizes and composition. The spherical shape of polymer particles and the uniformity of their size distribution are reviewed. The reaction mechanisms of polymer particle preparation in the micellar systems such as emulsion, miniemulsion and microemulsion polymerizations are described. The short section on radical polymerization mechanism is included. Furthermore, the formation of larger sized monodisperse polymer particles by the dispersion polymerization is reviewed as well as the assembling phenomena of polymer nanoparticles. 

In summary, there has been a tremendous effort devoted to the fundamental aspects of emulsion polymerization mechanisms, kinetics and processes since the early twentieth century. Representative review or journal articles concerning the conventional emulsion polymerization can be found in literature [20-25, 48-60]. The research areas related to both miniemulsion [42,61-64] and microemulsion [44-47, 65] polymerizations have received increasing interest recently. 

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