Water-in-oil polymerizations

Linear water-soluble anionic poly(acrylamide-co-ammonium acrylate) has been prepared by a water-in-oil polymerization. These materials are characterized by a Huggins constant in brine greater than 0.75 and a storage modulus for a 1.5 wt% actives polymer solution at 4.6 Hz greater than 175 Pa. These agents are particularly useful as drainage aids and contamination control aids in papermaking. 

Bartelt [5]. Therefore, due to historic precedent the description of water-in-oil polymerizations proceeds through an analogy, either colloidal or kinetic, to a process with a continuous aqueous phase. The prefix inverse is generally accepted for water-in-oil emulsions in contrast to direct or conventional oil-in-water emulsions/microemulsions for which the prefix is implied but not often explicitly stated. 

Table 1 compares the Suspension, Emulsion and Microemulsion regimes. The level of surfactant with respect to the CMC and the stability threshold, the locus of nucleation, and the particle size clearly distinguish these three regimes. This table also illustrates the analogies between direct oil-in-water and inverse water-in-oil polymerization processes with respect to the aforementioned attributes. To summarize As the concentration of emulsifier increases, at a fixed temperature, monomer level, and aqueous and organic phase ratio, a transition between the suspension, emulsion and microemulsion domains ensues. This occurs with a corresponding decrease in particle size. Within the... 

Over the past decade there has been extensive interest in the kinetics and colloidal behavior of water-in-oil polymerizations. However, these efforts have focused on the elucidation of a general set of phenomena to describe water-in-oil processes, without distinguishing inverse-emulsion and inverse-suspension sub-domains. A confounding factor is certainly the inconsistent nomenclature inverse-suspensions (Ila) are within the inverse-macroemulsion polymerization domain (II), and are often described as inverse-emulsions, where the prefix macro has been omitted for brevity. However, inverse-emulsion (lib) is itself a... 

Inverse-suspension, inverse-emulsion and inverse-microemulsion polymerizations should be developed independently as has been the precedent for oil-inwater polymerizations. This includes explicitly considering the unique chemistry of various emulsifiers, organic phases, monomers and initiators. Furthermore, the chemical and colloidal models for each of the three water-in-oil polymerizations will be specific to a given type of organic phase and a restricted family of emulsifiers. 

Investigations of water-in-oil polymerizations employing new monomers or emulsifiers for which kinetic or colloidal characterization is incomplete, require careful nomenclature designation. Under such circumstances a general description such as Water-in-Oil Polymerization or Heterophase Polymerization is recommended until the physical and chemical nature of the polymerizations can be identified. The designations inverse-suspension, inverse-emulsion and inverse-microemulsion should be reserved for processes for which a relatively advanced level of understanding exists. 

Plasma-initiated emulsion (ofl in water, water in oil) polymerization of various kinds of vinyl and diene monomers was carrkd out. Emulsified (0/W) isoprene (1 ) can be polymerized easily by a plasma exposure as short as 60 s, followed by post-polymoization at 25 °C [184]. The obtained pofyisoproie had a molar mass of 1.4 x... 

Among the different processes which have been developed for heterophase water-in-oil polymerizations, three of them should be cited which are... 

In an inverse emulsion polymerization an aqueous solution of a hydrophilic monomer is emulsified in an organic solvent and the polymerization is initiated with a solvent soluble initiator. This type of emulsion polymerizations is referred to as water in oil polymerization. Inverse emulsion polymerization is used in various commercial polymerizations and copolymerization of water-soluble monomers. Often nonionic emulsifiers are utilized. The product emulsions are often less stable than the oil in water emulsions. 

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