Silicone oil emulsion

When plastic syringes are used to store soybean oil emulsion, silicone oil may be extracted into the emulsion swelling of the syringe pump also occurs, resulting in the necessity for increased forces to maintain the motion of the plunger. " ... 

Diffusion mechanisms A internal emulsion - silicone oil bulk water, B direct diffusion across a water/oil/water interface C breaking of the internal emulsion at the bulk water interface. 

Aqueous or water containing suspensions or emulsions - silicon oil emulsions. 

An example of the first type is the emulsion stabiliser as exemplified by sodium oleyl sulphate, cetyl pyridinium chloride and poly(ethylene oxide) derivatives. For a number of applications it is desirable that the latex be thickened before use, in which case thickening agents such as water-soluble cellulose ethers or certain alginates or methacrylates may be employed. Antifoams such as silicone oils are occasionally required. 

Fig. 18. Comparison of results from various particle systems for stirred vessel with baffles and bubble columns Activity a/ao of Acylase resin after t = 300 h, equilibrium drop diameter dg of silicon oil-water-surfactant emulsion and reference floe diameter dpv of floe system in dependency on specific power P/V H/D = 1 D = 0.15 m 0.4 m...

The most widely studied deformable systems are emulsions. These can come in many forms, with oil in water (O/W) and water in oil (W/O) the most commonly encountered. However, there are multiple emulsions where oil or water droplets become trapped inside another drop such that they are W/O/W or O/W/O. Silicone oils can become incompatible at certain molecular weights and with different chemical substitutions and this can lead to oil in oil emulsions O/O. At high concentrations, typical of some pharmaceutical creams, cosmetics and foodstuffs the droplets are in contact and deform. Volume fractions in excess of 0.90 can be achieved. The drops are separated by thin surfactant films. Selfbodied systems are multicomponent systems in which the dispersion is a mixture of droplets and precipitated organic species such as a long chain alcohol. The solids can form part of the stabilising layer - these are called Pickering emulsions. 

The study of inverse adhesive emulsions has revealed the same features as direct emulsions [112,113]. Here again, it was shown that adhesion is favored when the surfactant becomes less soluble in the continuous phase [113]. This can be tested experimentally by using binary mixtures of oils, one in which the surfactant is soluble and another one in which the surfactant is insoluble. For example, water droplets can be stabilized in mineral oil by sorbitan monooleate (Span 80). This surfactant is soluble in dodecane whereas it is not in silicon oil. The affinity of the surfactant for the organic solvent can be tuned by mixing dodecane and silicon oil. As shown in Fig. 2.38, the energy of adhesion between water droplets strongly varies as the ratio of the mixture is changed. A sharp rise is noted as the surfactant... 

Eigure 4.2. The E dependence of the storage G (solid symbols) and loss G" (open symbols) moduli of a mono-disperse silicon oil-in-water emulsion stabilized with SDS, with radius a = 0.53 jam, for three volume fractions from top to bottom (j> = 77%, 60%, and 57%. The frequency is 1 rad/s the lines are visual guides. (Adapted from [10].)... 

Exemplary water-repellent treatments for masonry surfaces include metal stearates, oils, waxes, acrylates (both polymers and monomers), silicones (solvent-based and emulsion), siliconates, silanes and, fluorochemicals. In contrast, to waterproofing coatings, water-repellent coatings, because they are permeable to water vapor, do not trap moisture and, therefore they can reduce spalling. In addition most water-repellent coatings do not alter the appearance of a porous masonry. 

SIZING COMPOUND. 1. A material such as starch, gelatin, casein, gums, oils, waxes, asphalt emulsions, silicones, rosin, and water-soluble polymers applied to yarns, fabrics, paper, leather, and other products to improve or increase their stillness, strength, smoothness, or weight 2. A material used to modify the cooked starch solutions applied to warp ends prior to weaving. 

There is a considerable patent art concerning preparation of transparent mixtures of water with low molecular weight silicone oils using polymeric silicone surfactants. Some representative early references are Keil [47], Gee [48, 49], Gum [50] and Terae [51]. These compositions are called micro emulsions in the patents in the sense of being transparent mixtures of water, surfactant and oil - but note that they are transparent because of small particle size or because of index of refraction matching. 

No systematic studies of the use of silicone surfactants as emulsifiers have yet been published. Silicone polyoxyalkylene copolymers with relatively high molecular weight and a high proportion of silicone are effective water-in-silicone oil emulsifiers and a recent study of these copolymers suggests that they stabilize emulsions by a solid-particle mechanism [68]. This type of silicone surfactant has been used to prepare transparent water-in-oil emulsions (often with an active ingredient in the internal phase) for use as deodorants or antiperspirants as well as cosmetics and other personal care products. Their use as drug delivery vehicles has also been claimed. These copolymers can also be used to prepare multiple emulsions not requiring a two-pot process. 

T. M. Obey and B. Vincent, Novel, monodisperse silicone oil/water emulsions,. /. Colloid Interface Sci. 163, 454-463 (1994). 

As presented in Fig. 10.13, the effect of Triton X-100 at 0.25 CMC was remarkable. Mass transfer coefficients were 5-fold higher than those obtained in absence of surfactant. The dispersion of nonaqueous-phase, leading to an increase in contact area, and the facilitated transport of the pollutant, probably due to reduction of surface tension or interaction of the pollutant with single surfactant molecules, may explain this increase of the mass transfer coefficients at concentrations lower than CMC [ 131 ]. On the other hand, mass transfer coefficients increased slightly when the agitation rate was increased from 200 to 250 rpm, which was coincident with the formation of the emulsion. The effect of increasing to 300 rpm had little impact on the mass transfer coefficients. The value of kt a with Triton at 300 rpm was not determined due to an inefficient separation of both phases. Finally, silicone oil of 10 and 20 cSt led to similar results, while solvent with 50 cSt always led to lower mass transfer coefficients. 

To illustrate the general behavior, we consider an emulsion comprised of 2.5 wt % of 350 mPa s silicone oil dispersed in an aqueous phase. This latter contains 3 wt % of non-ionic surfactant (commercial mixture of polyethylene glycol C10E5 and... 

We now consider a 40% silicone oil premixed emulsion dispersed in an aqueous phase. In Fig. 9 the evolution of mean diameter is plotted as a function of the applied shear rate. The dispersed phase volume fraction is kept constant at 75%, while the emulsifier concentration in the continuous medium is varied from 15 wt % to 45 wt %. The error bars show the distribution width deduced from the measured uniformity. At a given shear rate, smaller droplets with lower uniformity are produced (see Fig. 9) when surfactant concentration increases. For example at 45% of Ifralan 205 the uniformity never exceeds 15% whatever the applied shear rate, whereas it is of the order of 25% for 15% of Ifralan 205. Some microscope pictures of the emulsions obtained are given in Fig. 10. To understand the evolution, we may argue that the continuous phase viscosity increases... 

The possibility to use Cm as a parameter characterising foam inhibition has been demonstrated for the first time in [60]. It was shown that the increase in the concentration of silicon oil Caf (antifoam) led to increase in Cm- That is why it was proposed to used the ratio Caf/Cm as a quantitative measure of the defoaming ability. However, it should be noted that the silicon oil concentrations at which inhibition of black spot formation was observed, were very low (10 5-10 9 %). For that reason it is difficult to conclude definitely whether the system was a real solution or represented a diluted emulsion of the antifoam in the surfactant solution. 

ZeUsko, R, Brook, M. A. Stabilization of a-Chymottypsin and Lysozyme Entrapped in Water-In-Silicone Oil Emulsions, Langmuir 2002,18, 8982-8987. 

The particles of cyclodextrin-grafted silicone are also the vehicles for the transport of the active substance to the site of its therapeutic action. In the case of anti-fnngal dosage form for topical administration action, penetration and slow release in the skin is searched for [21-23]. The stratum corneum top layer is made of cor-neocytes separated by a lipidic intercellular medium. Internal layers, epidermis and dermis are essentially aqueous media. The top layer is hydrophobic whereas the internal layers are hydrophilic. The penetration into the skin is controlled by the hydrophobic character of the particles. Hydrophobic materials easily penetrate and possibly accumulate in the stratum corneum. A slow release of the drug into the deep hydrophilic layers is possible from this medium. Silicone emulsions are often selected for cosmetic formulations because of the favorable spreading of silicone oils at the skin surface together with their low-irritancy properties. 

Fig. 5 Microscopy pictures of giiseofulvin crystals precipitated in water and out from a silicone emulsion. Top Giiseofulvin crystals precipitated by the spontaneous emulsification method 10 mg giiseofulvin in 2.5 mL acetone poured into 5 mL of 0.1 % Polysorbate 20 aqueous solution (left x 20, bar=200pm right xlOO, bar=20pm). Bottom lOmg silicone oil and 64mg giiseofulvin in 2.5 mL acetone poured into 5 mL of 0.1 % Polysorbate 20 aqueous solution (x 20, bar=200 pm)...

The presence of P-cyclodextrin grafts allows the formation of smaller emulsion droplets in comparison to systems formed using silicone oil. Thus, the diameters of PMHS-CD droplets were smaller than the silicone oil droplets by a factor of 2. The presence of substituents containing ester groups (20 ester groups per graft) makes the PMHS-CD polymers more polar than silicone oil. The backbone of PMHS-CD... 

Submicronic particles (nanoparticles) produced in that way allowed the encapsulation of the griseofulvin antifungal substance up to the 1 1 stoichiometry with respect to the P-cyclodextrin. A simple oil-in-water emulsion could not achieve such encapsulation because P-cyclodextrin was not soluble in common oils this was shown with silicone oil in the present study. The spontaneous emulsification process used for the preparation of the particles also allowed the easy encapsulation of the sparingly soluble griseofulvin. 

Type Silicone oil emulsion in water Appearance White liquid Density 3.5 lbs./gallon Solubility Readily disperses in water... 

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