Polymeric latex

The original Polacolot negative had water-coated intedayers of gelatin (60). The SX-70 and Polacolot 2 negatives use as intedayers a combination of a polymeric latex with a water-soluble polymer. A key development was the constmction of lattices that function as temporary batnets, reducing interimage problems. The water-soluble polymer functions as a permeator, so that the harder properties ate tunable (61). 

Cosolvents ana Surfactants Many nonvolatile polar substances cannot be dissolved at moderate temperatures in nonpolar fluids such as CO9. Cosolvents (also called entrainers, modifiers, moderators) such as alcohols and acetone have been added to fluids to raise the solvent strength. The addition of only 2 mol % of the complexing agent tri-/i-butyl phosphate (TBP) to CO9 increases the solubility ofnydro-quinone by a factor of 250 due to Lewis acid-base interactions. Veiy recently, surfac tants have been used to form reverse micelles, microemulsions, and polymeric latexes in SCFs including CO9. These organized molecular assemblies can dissolve hydrophilic solutes and ionic species such as amino acids and even proteins. Examples of surfactant tails which interact favorably with CO9 include fluoroethers, fluoroacrylates, fluoroalkanes, propylene oxides, and siloxanes. 

The polymeric latex obtained in a hydrophobic organic solvent is poorly dispersed in water because of the presence of an emulsifier with a low HLB value. For this reason, a wetting agent is added to water or emulsion prior to the dissolution. The wetting agent (a surface active substance with a high HLB value) facilitates the inversion of latex phases to produce a direct type emulsion. Usually, it belongs to oxyethylated alkylphenols, fatty alcohols, or fatty acids. 

Research on the modelling, optimization and control of emulsion polymerization (latex) reactors and processes has been expanding rapidly as the chemistry and physics of these systems become better understood, and as the demand for new and improved latex products increases. The objectives are usually to optimize production rates and/or to control product quality variables such as polymer particle size distribution (PSD), particle morphology, copolymer composition, molecular weights (MW s), long chain branching (LCB), crosslinking frequency and gel content. 

The original polymeric latex particles still are widely used for separation and detection. Polymers provide a matrix that can be swollen for embedding other molecules in their core, such as organic dyes or fluorescent molecules. Even nanoparticle quantum dots can be incorporated into larger latex particles to form highly fluorescent composite microparticles. 

Chain-transfer agents -m emulsion polymerization [LATEX TECITNOLOGY] (Vol 15) -for fluorocarbon elastomers [ELASTOMERS, SYNTHETIC - FLUOROCARBONELASTOMERS] (Vol 8)... 

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Band broadening HDC, 259-260 sedimentation FFF, 223 Batch polymerization, latex, 266-267 Bentonite suspensions dynamic light-scattering... 

In choosing an epoxy and polymeric latex, it is important that they have compatibility. Incompatibility usually occurs when the pH of the epoxy resin dispersion alters the pH of the latex into a range where the ionically stabilized latex is broken, causing agglomeration of the latex polymer. The pH of the epoxy resin s emulsion may need to be adjusted before blending with the polymeric latex. 

Colloidal stability is usually controlled by the type and amount of the employed surfactant. In miniemulsions, the fusion-fission rate equilibrium during sonication and therefore the size of the droplets directly after primary equilibration depends on the amount of surfactant. For sodium dodecylsulfate (SDS) and styrene at 20% dispersed phase, it spans a range from 180 nm (0.3% SDS relative to styrene) down to 32 nm (50 rel.% SDS) (Fig. 4a). Again, it is anticipated that rapidly polymerized latexes also characterize the parental miniemulsion. As... 

Butadiene-Styrene 75/25 Rubber (Emulsion-Polymerized Latex)... 

In the conventional emulsion polymerization, monomer droplets are dispersed ip an aqueous phase containing micellar aggregates of surfactant. In this case, the dispersed phase represents a relatively small volume fraction of the system and the micellar aggregates constitute the sites of the polymerization process. In the gel(paste)-like emulsions employed here, the volume fraction of the dispersed phase can be as high as 0.99, and the cells of the concentrated emulsion lead to the polymerized latex particles. 

Concentrated Emulsion Pathway to Toughened Polymeric Latexes... 

NMR analysis indicated that approximately 30% of the alkyd double bonds had been consumed in the polymerization process. This is important in that it indicates that a substantial fraction of the double bonds remain for oxidative crosslinking while a coating made from this material is dried. Selective extraction indicated that approximately 60% of the acrylate was grafted to alkyd. Exhaustive extraction indicated less than 5% crosshnked material. The polymerized latex formed good films with acceptable hardness. 

Unsteady start-up behavior has been reported in some continuous reactors (14). In this work, the reactor was initially filled with water or partially polymerized latex, and the % conversion asymptotically approached a constant steady-state value, which required less than twice the residence time in the reactor. 

Examples of aqueous coating solutions include water-soluble low molecular weight cellulose ethers, emulsion polymerization latexes of polymethacrylates, and dispersions of water-insoluble polymers such as ethyl-cellulose in the form of pseudolatex. These solvent-free coating solutions provide a range of different coatings... 

Intramolecularly cross-linked polymeric latex particles that are swollen in a good... 

Sulfonic acid polymeric, latex coated Dionex CS3,CS 0, CSll... 

A very simple method to obtain polymeric dispersions in liquid polyethers is to make a mixture between a polyether polyol and a polymeric latex, such as the azeotropic copolymer styrene - ACN (StACN copolymer), obtained by emulsion copolymerisation, having around 20-40% solid content. The water is eliminated step-by-step by vacuum... 

Synthetic polymeric latexes can be produced by processes that are different from the standard emulsion polymerization methods described in this chapter. Two such processes, inverse emulsion polymerization and direct emulsification, are described briefly in order to make this paper more complete. The literature on these processes is less extensive, but interest in such processes has recently increased. 

Epan. Pai-ichi Kogyo Sdyaku] PPG PEG ether emukffier, dispersant, lubricant, defoamer, detergent fix d -gents, emukion polymerization, latexes. 

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