Catálogo de publicaciones - libros

The current understanding of the kinetics and mechanisms of batch and continuous emulsion polymerizations is summarized from the viewpoints of particle formation and growth and polymer structure development. There are numerous factors that affect these processes; among them, studies on the radical transfer and monomer partitioning between phases, which are key factors for particle formation and growth, are reviewed and discussed. Attention is also focused on the effects of initiator type, additives and impurities in the recipe ingredients, and agitation, each of which sometimes exert crucial influences on the processes of particle formation and growth. In relation to polymer structure development, important aspects of the molecular weight distribution and branched/crosslinked polymer formation are highlighted.

The subject of miniemulsion polymerization is reviewed. The approach taken is one that combines a review of the technology with historical and tutorial aspects. Rather than developing an absolutely exhaustive review, a tutorial approach has been taken, emphasizing the critical features and advantages of miniemulsion polymerization. In keeping with this tutorial approach, a discussion of conventional emulsion polymerization is included in order to be able to compare and contrast miniemulsion polymerization and conventional emulsion polymerization later in the review. Areas where miniemulsion polymerization has been adopted commercially, or where it is likely to be adopted are highlighted.

This review describes how the unique nanostructures of water-in-oil (W/O), oil-in-water (O/W) and bicontinuous microemulsions have been used for the syntheses of some organic and inorganic nanomaterials. Polymer nanoparticles of diameter approximately 10–50 nm can easily be obtained, not only from the polymerization of monomers in all three types of microemulsions, but also from a Winsor I-like system. A Winsor I-like system with a semi-continuous process can be used to produce microlatexes with high weight ratios of polymer to surfactant (up to 25). On the other hand, to form inorganic nanoparticles, it is best to carry out the appropriate chemical reactions in W/O- and bicontinuous microemulsions. Recent developments in the cross-polymerization of the organic components used in bicontinuous microemulsions ensure the successful formation of transparent nanostructured materials. Current research into using polymerizable bicontinuous microemulsions as a one-pot process for producing functional membranes and inorganic/polymer nanocomposites is highlighted with examples.

Dispersion polymerization is an attractive method for producing micron-size monodisperse polymer particles in a single batch process. Great progress in this field has been achieved over the past two decades. This article presents an overview of the recent progress in the preparation of polymeric microspheres via dispersion polymerization in organic media, focusing on the preparation of novel functional particles, the design of microspheres using macromonomers, and on understanding mechanisms for the control of particle size. Examples of functional microspheres obtained by dispersion polymerization in the presence of linear polymers, block polymers, and macromonomers are tabulated, and new developments are highlighted. Particle size control in dispersion polymerization in the presence of macromonomers is discussed, and experimental results for poly(ethylene oxide)-grafted particles are compared with theoretical expectations for ideal core-shell particles.

In recent years, carbon dioxide has been investigated for its potential to replace the aqueous and organic solvents used in polymerization processes. Carbon dioxide has several benefits, including being environmentally benign, a tunable solvent, resistant to chain transfer, and of low viscosity which facilitates high initiator efficiencies and fluid handling. Homo- and copolymerization of fluoroolefins such as tetrafluoroethylene (TFE), vinylidene fluoride (VF2), hexafluoropropylene (HFP), and perfluorinated vinyl ethers in carbon dioxide are particularly interesting because of the significant waste reduction and the elimination of potentially harmful processing agents. This review focuses on recent developments in polymerizing fluoroolefins via heterogeneous polymerization in carbon dioxide. At least one CO_2-based polymerization process has recently been commercialized, and additional research is underway to understand the kinetics associated with polymerizing fluoroolefins in carbon dioxide. As researchers improve their understanding of CO_2-based polymerizations, and as industry continues to look for more economically and environmentally-sound alternatives to existing processes, it will become more and more common to employ carbon dioxide as a polymerization medium.