Polymerizations homogeneous

Vinyl ethers constitute a third class of monomers which have been cationically polymerized in C02. While fluorinated vinyl ether monomers such as those described in Sect. 2.1.2 can be polymerized homogeneously in C02 because of the high solubility of the resulting amorphous fluoropolymers, the polymerization of hydrocarbon vinyl ethers in C02 results in the formation of C02-insoluble polymers which precipitate from the reaction medium. The work in this area reported to date in the literature includes precipitation polymerizations and does not yet include the use of stabilizing moieties such as those described in the earlier sections on dispersion and emulsion polymerizations (Sect. 3). 

Before Polymerization Homogeneous Solution Macromonomers (l) + Monomers (°) + Initiators ( ) (Omitted in the Stage 2-5)... 

Perfluoroalkyl (meth)acrylates FM-12 and FM-15 have been polymerized homogeneously in SCCO2 with copper catalysts/fluorinated ligand systems, but the MWDs of the products are not reported due to the lack of appropriate analytical methods.95 Other flu-orinated monomers (FM-13 and FM-14) were used for block copolymerization with styrene and acrylates with CuBr/L-1 in the bulk under heterogeneous conditions.315... 

Transition metal catalyzed, ring opening polymerization Dispersion, cationic polymerization Homogeneous/precipitation, cationic polymerization Homogeneous, free radical/cationic polymerization Precipitation, free radical polymerization Dispersion, free radical polymerization Norbornene polymer, polycarbonate Isobutylene polymer Vinyl ether polymer Amorphous fluoropolymers Vinyl polymer, semicrystalline fluoropolymers Polyvinyl acetate and ethylene vinyl acetate copol5Tner... 

With growing data banks of rate constants of elementary steps, it appears that kinetics assisted design of new catalytic processes will accelerate the development of improved catalytic processes. With powerful computational methods of thermodynamic and kinetic parameters, microkinetic analysis has emerged as a mature method to describe existing processes in combustion, polymerization, homogeneous and heterogeneous catalysis. In catalysis, the method is now poised to become one of the tools of catalyst development with the help of surface science, organometallic chemistry, materials science, com-... 

Precipitation polymerization is similar to dispersion polymerization. They both start as a solution polymerization (homogeneous phase). However, in the case of precipitation polymerization, there is no colloidal stabilizer present, and so the polymer formed precipitates as a completely separate phase, while in dispersion polymerization, the polymer particles are stabilized by a colloidal stabilizer. 

The experimental controls where no seeds were included polymerized homogeneously indicating that it is necessary to include a seed for IFF to occur. Controls that included seeds and a polymeric inhibitor to illustrate seed dissolution showed an initial sharp dip that did not move up the reaction vessel but instead diffused with time indicating no reaction taking place. 

Hutchinson, R.A. (2005) Free-radical polymerization homogeneous. In T. Meyer and Keurentjes (eds), Handbook of Polymer Reaction Engineering. John WUey Sons, Inc., New York, pp. 153-212. 

Fluid-fluid systems are widely used in chemical, petroleum, pharmaceutical, hydrometaflurgical, and food industries. Commercially important examples of gas-liquid mass transfer with or without reaction include gas purification, oxidation, halogenations, hydrogenation, and hydroformylation to name but a few. Important liquid-liquid reactions include nitration, phase transfer catalysis (PTC), cyclization, emulsion polymerization, homogenous catalyst screening, enzymatic reactions, extraction, precipitation, crystallization, and cell separation. 

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