Multistage emulsion polymerization

Multistage emulsion polymerization techniques are usually applied for (1) the synthesis of large uniform latex particles, (2) the introduction of functional groups into the uniform latex particles, or (3) the synthesis of macroporous uniform latex particles. 

Multistage emulsion polymerization has been proposed by Ugelstad et al. [108,109] for the synthesis of large uniform latex particles. In general, the multistage emulsion polymerization techniques include two main... 

Uniform macroporous polymer particles have been prepared in the size range of 5-20 iitm by the multistage emulsion polymerization methods. Several methods are available in the literature describing the synthesis and the properties of macroporous uniform particles. The main steps of these methods may be summarized as follows. 

As mentioned before, hybrid latex particles are usually prepared by seeded emulsion polymerization. In the first stage, well-defined inorganic or organic particles are prepared, while in the second stage a monomer is polymerized in the presence of these well-defined particles. Multistage emulsion polymerization produces structures such as core-shell, inverted core-shell structures, and phase-separated structures such as sandwich structures, hemispheres, raspberry-like and void... 

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

Particle nucleation and particle growth are important steps in emulsion polymerization because they affect the overall polymerization rate and polymer properties. Thus, initiator concentration and surfactant type/concentra-tion have significant effects on the polymerization kinetics. In a batch emulsion process, particle nucleation and growth steps can be separated to some extent by employing a multistage reaction process. In a continuous process, both particle nucleation and growth steps occur simultaneously unless a seed reactor is provided to separate these two effects. In general, latex particle size distributions obtained by batch and continuous processes are quite different. 

Copper mandelates react with pho ene and then pyridine to give 1,3-dioxoIan-2,4-diones, and application of this reaction to the pentafluoroKxnnpound [CeFe -C(0H)Me-C08]2Cu yields the substituted dioxolan (127) (62%). Compounds of this type give derivatives of the parent acid when they are treated with amines or alcohols, and may be polymerized to polyesters details of these reactions are awaited. Pentafluorobenzoic acid is converted into pentafluoroiodobenzene by treatment with iodine in the presence of a peroxide initiator, and certain penta-fluorobenzamido-derivatives of 4-fluorophenol, e.g. (128), prepared by conventional multistage syntheses from the parent phenol, are claimed to be useful as colour-formers in photographic emulsions. i... 

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