Emulsifier polyvinyl alcohol

Figure 3. Effect of NaOH on thioridazine release from poly(DL-lactide) microspheres. Key (o) no NaOH, 15-85 pm ( ) 0.14 mole NaOH/mole lactic acid, 10-85 pm. Drug loading, 50%. Emulsifier, polyvinyl alcohol.

Differences and similarities are illustrated by example. Suspension and emulsion polymerizations are examples of industrial processes having high drop concentrations, where coalescence is prevented by the use of suspending agents/emulsifiers. Polyvinyl alcohol (PVA) is typical of the aqueous suspending agents used. Concentrates of of partially hydrolyzed PVA are diluted to >=a0.05 to 0.2%... 

Emulsion polymerization is widely used to produce polymers in the form of emulsions, such as paints and floor polishes. It also used to polymerize many water insoluble vinyl monomers, such as styrene and vinyl chloride. In emulsion polymerization, an agent emulsifies the monomers. Emulsifying agents should have a finite solubility. They are either ionic, as in the case of alkylbenzene sulfonates, or nonionic, like polyvinyl alcohol. 

The stabilizing of aqueous latexes succeeded by using emulsifiers (anionic, nonionic) and/or their mixture, steric stabilizators (polyvinyl alcohol (PVOH), hydroxyethyl cellulose, polyethylene glycol, new protective colloids etc.), and polymerizable surfaces active agents, in general. Vinyl acetate (VAc) emulsion homopolymers and copolymers (latexes) are widely used as binders in water-based interior and exterior architectural paints, coatings, and adhesives, since they have higher mechanical and water resistance properties than the homopolymers of both monomers [2, 4, 7]. 

Additional crosslinked polyvinyl alcohol copolymers, (I), were prepared by Schulte et al. (1) and used as components in adhesives, emulsifiers, and detergents. 

The rubber particle size in the final product increases several fold if the prepolymerization is carried out in the presence of a dilute aqueous solution of an alkane sulfonate or polyvinyl alcohol in place of pure water. The addition of a surface-active agent converts the coarsely dispersed oil-water mixture—obtained as above in the presence of pure water—into an oil-in-water emulsion. In this case even prolonged stirring during prepolymerization does not decrease the rubber particle size appreciably in the final product. The stabilization of the droplets of the organic phase in water by the emulsifier obviously impedes or prevents agitation within the polymeric phase. Figure 1 shows the influence of these three prepolymerization methods (under otherwise equal reaction conditions) on the dispersion of rubber particles in polystyrene. 

Polyvinyl alcohol - This polymer was dissolved in water and did not form a continuous film, and the hydrophilic property prevented the formation of a barrier film. This emulsion consists of emulsified particles that must fuse during evaporation of water and form a film, but cannot do so if the water phase remains which is what happened in this case. 

A solution of 1.0 g of thioridazine free base and 1.0 g of poly(DL-lactide) or poly(L-lactide) in 10 mL of methylene chloride was emulsified with 100 mL of an aqueous solution containing 0.4 g of sodium oleate or polyvinyl alcohol and 0-15 mL of 0.1 N NaOH (0-0.14 mole NaOH/mole lactic acid). After the emulsion was magnetically stirred for 10-15 minutes, the organic solvent was removed by rotary evaporation, 150 rpm, 375 mm Hg, at 40°C for 2 hours. The product was filtered, washed with water and vacuum dried at 30°C. 

The effect of NaOH on drug release was examined with microspheres prepared with thioridazine and two biodegradable polymers. The wall-forming polymers were poly(DL-lactide) and poly(L-lactide). Sodium oleate was used as the emulsifier, with the exception of one set of experiments where the emulsions were stabilized with polyvinyl alcohol. 

In order to determine whether the effect of NaOH was specific to the use of sodium oleate as the emulsifier, microspheres were also prepared using polyvinyl alcohol to stabilize the emulsion. Figure 3 indicates that there was only a moderate increase in drug release by the addition of NaOH to the emulsion. 

To recapitulate, thioridazine release from microspheres was enhanced when NaOH was added to the emulsion prior to the solvent evaporation step. This was observed for both poly(DL-lactide) and poly(L-lactide) and also for two emulsifier systems, sodium oleate and polyvinyl alcohol. It should be pointed out that NaOH is added only to the aqueous phase of the emulsion. It is not incorporated into the microspheres by this process. 

Terpolymers of ethylene, vinyl acetate and N15AK ac e prepared by adding the lal er two inder constant ethylene pressure into an initiated emulsifier solution containing polyvinyl alcohol, controlling the amount of unpolymerised vinyl acetate at any one time to be under This method enables ethylene to be copolymv... 

Paper and Textiles Gelatins, Casein, Starch, Gums, Latex, Dextrin, Polyvinyl Alcohol, Fluorochemicals, Emulsifiers,... 

III. The third group includes polymerizations carried out in the presence of nonionic macromolecular emulsifiers, among which ethylene oxide-propylene oxide block copolymers and polyvinyl alcohol are most largely used. 

Polyvinyl ehloride 300 water 0.2 polyvinyl alcohol, or 0.5 gelatin 0.05 emulsifier 0.2 laiwoyl peroxide 130-140 F 100-200 psi 10-12 h 18%... 

Zhu, G. Lu, L. Tang, J. Dong, B. Han, N. Xing, F. Prepararion of mono-sized epoxy/MF microcapsules in the appearance of polyvinyl alcohol as co-emulsifier. Proceedings of the Fourth International Conference on Self-Healing Materials, Ghent, 2013, pp. 225-228. 

For instance, Yadav and Ahuja prepared nanoparticles using gum cordia as the polymer and to evaluate them for ophthalmic delivery of fluconazole. A w/o/w emulsion containing fluconazole and gum cordia in aqueous phase, methylene chloride as the oily phase, and dioctyl sodium sulfosuccinate and polyvinyl alcohol as the primary and secondary emulsifiers, respectively, were cross-linked by the ionic gelation technique to produce a fluconazole-loaded nanoreservoir system. The formulation of nanoparticles was optimized using response surface methodology. Multiple response simultaneous optimizations using the desirability approach were used to find optimal experimental conditions. The optimal conditions were found to be concentrations of gum cordia (0.85%, w/v), di-octyl sodium sulfosuccinate (9.07%, w/v), and fluconazole (6.06%, w/v). On comparison of the optimized nanosuspension formulation with commercial formulation, it was found to provide comparable in vitro corneal permeability of... 

General Description A white-to-cream granular powder, DuPont Elvanol polyvinyl alcohol (PVOH) is a water-soluble synthetic polymer with excellent film-forming, emulsifying, and adhesive properties. This versatile polymer offers a high oxygen bar-... 

In nature as well as in technology, polymeric emulsifiers and stabiUzers play a major role in the preparation and stabiUzation of emulsions. Natural materials such as proteins, starches, gums, cellulosics, and their modifications, as well as synthetic materials such as polyvinyl alcohol, polyacryhc add, and polyvinylpyrrolidone, have several characteristics that make them extremely useful in emulsion technology. By the proper choice of chemical composition, such materials can be made to adsorb strongly at the interface between the continuous and dispersed phases. By their presence, they can reduce interfacial tension and/or form a barrier (electrostatic and/or steric) between drops. In addition, their solvation properties serve to increase the effective adsorbed layer thickness, increase interfacial viscosity, and introduce other factors that tend to favor the stabilization of the system. 

Some surfactants such as Triton X-100, OP emulsifier, and polyvinyl alcohol are commonly used to make some reagents soluble so that solutions can be prepared. 

High solids polymer latices up to 70% solids content are prepared by conventional emulsion polymerisation from different monomer systems. Emulsifier but also polyvinyl alcohol stabilisation is used. Polymerisation process is executed as a two-step seeded but also as a single-step process. When using known concepts for the control of viscosity for high solids, a high shear viscosity below 50 mPas is achieved even for 70% solids. Quantitative mathematical evaluation of the viscosity depending on bimodal particle size distribution and on the hydrodynamic particle surface layer is possible. 8 refs. 

The above triblocks are not the most efficient emulsifiers or dispersants—the PPO chain is not sufficiently hydrophobic to provide a strong anchor to a hydrophobic surface or to an oil droplet. The surface activity of the PEO-PPO-PEO triblock at the OAV interface is probably due to rejection anchoring the PPO chain is not soluble in water or most oils. Several other di- and triblock copolymers have been synthesized diblocks of polystyrene block-polyvinyl alcohol triblocks of poly(methylmethacrylate)-block polyethylene oxide-poly(methyl methacrylate) diblocks of polystyrene-polyethylene oxide triblocks of polyethelene oxide-polystyrene-polyethylene oxide. 

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