Aerosol emulsification

Emulsions and suspensions are colloidal dispersions of two or more immiscible phases in which one phase (disperse or internal phase) is dispersed as droplets or particles into another phase (continuous or dispersant phase). Therefore, various types of colloidal systems can be obtained. For example, oil/water and water /oil single emulsions can be prepared, as well as so-called multiple emulsions, which involve the preliminary emulsification of two phases (e.g., w/o or o/w), followed by secondary emulsification into a third phase leading to a three-phase mixture, such as w/o/w or o/w/o. Suspensions where a solid phase is dispersed into a liquid phase can also be obtained. In this case, solid particles can be (i) microspheres, for example, spherical particles composed of various natural and synthetic materials with diameters in the micrometer range solid lipid microspheres, albumin microspheres, polymer microspheres and (ii) capsules, for example, small, coated particles loaded with a solid, a liquid, a solid-liquid dispersion or solid-gas dispersion. Aerosols, where the internal phase is constituted by a solid or a liquid phase dispersed in air as a continuous phase, represent another type of colloidal system. 

Emulsification is widely used in pharmaceutical products for external application such as lotions and creams, and in aerosol products to form foams. Semisolid emulsified formulations are discussed below. 

Emulsification is used in aerosol products to produce foams which are generally formulated as o/w emulsions. The liquified propellant forms the disperse phase of the emulsion, and the medication is usually in the aqueous continuous phase. On discharge from the pressurised container, the propellant vaporizes to form bubbles which remain trapped within the aqueous phase giving rise to a foam. These are referred to as stable foam products. Nonaqueous stable foams may also be formulated, where the water is replaced by various glycols such as polyethylene glycol. Quick breaking foams result when the propellant is in the external phase. The product is emitted as a foam and collapses into a liquid. 

Ultrasmall hydrophilic PAAm nanogels were prepared by direa emulsification of both AAm and N,N-methylene bisaayla-mide as a aoss-linka into hexane/dioctyl sodium sulfosucdnate (aerosol OT), which allowed the preparation of PAAm NPs with a... 

The measurements were conducted using the Rank Brothers Particle Microelectrophoresis Apparatus Mark II equipped with a flat cell. Samples were prepared by diluting a lOOpl sample of the oil-in-water emulsion with 20 ml of 10 M NaCl containing Aerosol OT (0 to 100 ppm). In experiments with Duomeen C, the reagent was added to the oil phase in the desired amount prior to emulsification. The pH was adjusted using HCl or NaOH to cover the range 2.5 to 11.5. All experiments were conducted at 30 C. 

Some important processes for the formation of sols involve first the formation of an emulsion or a liquid aerosol. In suspension or dispersion polymerization, a monomer or monomer mixture is emulsified to a drop size approximately the same as that of the final desired particle. Polymerization is then initiated using an initiator soluble in the monomer, so that chain growth occurs within each individual drop. The result (with luck) is a dispersion of polymer particles with the same average size as the original monomer emulsion. Normally, some type of stabilizer system is employed in the emulsification stage—a surfactant or very small particles of some material such as silica. 

Nishimi, T. and Miller, C. A., Spontaneous emulsification of oil in aerosol-OT/water/hydro-... 

General purpose grade of AEROSOL OT for dust control, general wetting, emulsification and dispersion. 

Waxy solid form of AEROSOL OT. Used for emulsification, dispersion, lubricating, wetting and water displacement. Excellent mold release properties. Surface active agent for water-free systems. 

Regulatory FDA 21CFR 175.105,175.300,176,170,176,180,176,200 Properties Milky liq. emulsifable in water sp.gr, 1,04 vise, 9000 cps vapor pressure 24.51 mm Hg b.p. 100 C pH 7.3 0.3% VOC Toxicology Contact with eyes may cause irritation mild skin irritant may cause nose, throat, and lung irritation inh. ofvapors and/or aerosols in high cone, may cause irritation of respiratory system... 

Uses Emulsifier for cosmetics, pharmaceuticals, aerosols internal lubricant, plasf-cizer, and emulsifer in industrial applies. fow control agent for polymerization reactions dispersant... 

Uses Binder, emulsif er, surfactant, dispersant, emollient for cosmetics, pharmaceuticals, creams/lotions chemicals softener in rubber compds., food pkg., suppositories, ointments deleaf ng inhibitor (aerosol metallic paints) deterigent intermediate for personal care, household and industrial applies. soap/shampoo ingred. mfg. of esters, lubricants, cosmetics, soaps, creams, textile and plastic auxs., plasticizers... 

Normally, alkaline catalysts are used because there are less by-products and corrosion of the equipment. Alkaline catalysis however, leads to a broad spectrum of homologous polyglycol ethers (n = 0- 12), which may cause problems later in detergent manufacturing (pluming, which is the formation of aerosols in the exhaust of the spray tower). Sometimes they have advantages in emulsification behavior. Acidic catalysis leads to a narrower distribution of EO units but can yield undesired byproducts, e.g., dioxane. Many attempts have been... 

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