Preparation of polymer-based nanomaterials

Mixtures of oil, water and an emulsifier (surfactant) have attracted much attention in colloid science. Oil and water are essentially not miscible and coexist as a water and oil phase, each saturated with traces of the other component. Emulsifiers are fairly soluble in one or both solvents but form a true molecular solution of emulsifier monomer molecules at low concentrations only. At higher concentrations of emulsifier monomers aggregate into micelles. Three- or four-component mixtures containing water, oil, an emulsifier and coemulsifier can form not only kinetically stable emulsions but also thermodynamically stable microemulsions. 

An emulsion is a dispersion of one liquid in another where each liquid is immiscible, or poorly miscible in the other [1]. Emulsions exhibit all classical behaviors of metastable colloids Brownian motion, reversible phase transitions as a result of droplet interactions that may be strongly nradified and irreversible transitions that generally involve their destruction. They are obtained by shearing two immiscible fluids to the fragmentation of one phase into the other. From diluted to highly concentrated, emulsions exhibit very different internal dynamics and mechanical properties. Emulsifiers are usually added to oU/water mixture to enhance the formation of stable monomer emulsions. The molecules of emulsifier adsorb to the surface of oil droplets during homogenization and provide a protective membrane 

Polymer (latexes) dispersions are generated by the radical polymerization of unsaturated monomers solubilized in the micellar systems. The significant growth in the production of these latexes is due to a number of factors such as  

1) The water-based dispersions, especially paints and coatings, are mostly environmentally-friendly because they avoid of the environmental problems associated with the solvent-based applications. 

2) The emulsion polymerization is fast and proceeds smoothly and controllably within the large range of monomers and reactants and their amounts. 

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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. 

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