Sizing polymeric

M. Granstrom, M. Berggren, and O. Inganas, Micrometer- and nanometer-sized polymeric light emitting diodes, Science, 267 1479-1481, 1995. 

M. Granstrom and O. Inganas, Flexible arrays of sub-micron sized polymeric light-emitting diodes, Adv. Mater., 7 1012-1015, 1995. 

This example clearly shows that introducing the concept of down-sizing polymerization reactions sequences can give useful novel MCRs. 

Emulsion polymerization is a free radical initiated chain polymerization in which a monomer or a mixture of monomers is polymerized in aqueous solution of a surfactant to form a product, known as a latex. The most important feature of emulsion polymerization is its heterogeneity from the beginning to the end of the polymerization, to yield in a batch process submicron-sized polymeric particles, often of excellent monodispersity. The main ingredients for conducting... 

Figure 9 Close-up of packed-bed weir-SMEC using 20-pm-particle-sized polymeric support material. The homogenious packing structure of the packed bed can be seen on the left-hand side lining up close to the eight-channel microfluidic grid...

Nanoparticles Nanoparticles have been among the most widely studied particulate delivery systems over the past three decades. They are defined as submicrometer-sized polymeric colloidal particles ranging from 10 to 1000 nm in which the drug can be dissolved, entrapped, encapsulated, or adsorbed [206]. Depending on the preparation process, nanospheres or nanocapsules can be obtained. Nanospheres have a matrixlike structure where the drug can either be firmly adsorbed at the surface of the particle or be dispersed/dissolved in the matrix. Nanocapsules, on the other hand, consist of a polymer shell and a core, where the drug can either be dissolved in the inner core or be adsorbed onto the surface [207],... 

Cyclic ethers of various ring size polymerize by cationic mechanism, including oxiranes (3-membered), oxetanes (4-membered), oxolanes (5-membered), oxepanes (7-membered), and larger rings. Six-membered cyclic ethers do not polymerize because of the thermodynamic restrictions. Oxiranes may be also polymerized by anionic mechanism, whereas for other groups the cationic polymerization is the only mechanism of polymerization. 

There are four main types of liquid-phase heterogeneous free-radical polymerization microemulsion polymerization, emulsion polymerization, miniemulsion polymerization and dispersion polymerization, all of which can produce nano- to micron-sized polymeric particles. Emulsion polymerization is sometimes called macroemulsion polymerization. In recent years, these heterophase polymerization reactions have become more and more important... 

Ugelstad et al. [52] have shown how this theory may be used to devise a method to prepare large monodisperse particles of predetermined size. By using the appropriate amount of cosurfactant, polymer particles can be swollen with monomer to the desired size. Polymerization in conditions that prevent additional nucleation results in large monodisperse polymer particles of size 1-100 pm. This method has been criticized by other groups as being in error due to measurement selectivity. 

Interchange reactions represent an approach to an equilibrium distribution of molecular sizes. Polymerizations that use very reactive monomers can proceed at room temperature [as in reaction (c) of Fig. 5-2]. They are kinetically controlled and will not produce random molecular weight distributions. Polymers from such syntheses will undergo interchange reactions, however, if they are subsequently heated to temperatures at which the equilibria such as that of reaction (5-14) can be reached in a reasonable time. 

Eckner and Zottola (cited in Ref. [124]) reported that sterilizing microfilters, such as the 0.2 p,m membranes commonly used in the pharmaceutical industry, would foul too rapidly when operated in the conventional crossflow manner, resulting in low flux and permeates with an undesirable solids profile, making them of little practical value in the dairy industry. Guerra et al. [102] employed the combined benefits of reverse asymmetric 0.87 p.m pore size polymeric membranes and backshock technique to control the adverse effects of concentration polarization and fouling in the removal of bacterial spores in skim milk... 

Phase separation is utilized for the fabrication of porous membranes and it allows for the generation of three-dimensional (3D) porous networks within the scaffolds. Considering the relationship of specific cells and pore sizes, polymeric... 

The air interface provided by a microvoid is capable, theoretically, of almost doubling the optical efficiency of the titanium dioxide with which it is used, but the necessary volume of the microvoid multiplies the overall concentration of non-film-forming material in the coating by as much as four times. An ultrafine particle size polymeric bead can perform the function of a titanium dioxide "spacer," but there is little application for such in very low PVC finishes. These considerations essentially restrict the application of plastic pigments and microvoids to more highly pigmented trade sales coatings—and more particularly to flat latex paints, because of their solubility characteristics. 

Chance B 1991 Optical method Annu. Rev. Biophys. Biophys. Chem. 20 1-28 Granstrom M, Berggren M and Ingan s O 1995 Micrometer- and nanometer-sized polymeric light-emitting diodes Science 267 1479-81 Hanken D G and Com R M 1995 Variable index of refraction ultrathin films formed from self-assembled zirconium phosphonate multilayers Characterization by surface plasma resonance measurements and polarization/modulation FT-IR spectroscopy Anal. Chem. 67 3761-74... 

Smigol, V. Svec, F. Frechet, J.M.J. Novel uniformly sized polymeric stationary phase with hydrophilized large pores for direct iiqection HPLC determination of drugs in biological fluids. J.Liq.Chromatogr.,... 

Particle size, polymerization rate, ai solid content of the final latexes remain unchanged compared with polymerizations with the unreacted individual components of the inisurfe (water soluble non-surface-active azo-bis (di-isobutyric acid amidine) and a C15-alkylmonosulfonate as emulsifier in the case of Inisurf 4 and a potassium salt of co-aminoundecanoic acid as emulsifier in the case of Inisurf 5, respectively). 

Figure 6.2 Examples of static self-assembly, (a) Crystal structure of a ribosome, (b) Self-assembled peptide-amphiphile nanofibers, (c) An array of millimeter-sized polymeric plates assembled at a water/perfluorodecalin interface by capillary interactions, (d) Thin film of a nematic liquid crystal on an isotropic substrate, (e) Micrometer-sized metallic polyhedral folded from planar substrates, (f) A 3-D aggregate of micrometer plates assembled by capillary forces.

Glass type Polymeric size Polymeric binder Application... 

Nevertheless, on-line sound velocity is one of the more promising techniques for monitoring industrial-size polymerization reactors because of the fast and robust measurement and easy maintenance at a relatively low cost. 

FIGURE 10.8 [R ]p versus time for various particle size polymerizations. Reprinted (adapted) with permission from Parker H-Y, Westmoreland DG, Chang H-R. ESR study of MMA batch emulsion polymerization in real time effects of particle size. Macromolecules 1996 29 5119-5127. 1996 American Chemical Society. 

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