Suspensions cosmetic, types

Cosmetic suspensions are available in two types. The first comprises pigmented products that are suspended in essentially aqueous vehicles (liquid makeup, eyeliners, mascara, and blusher). These products have a high solids content, high density, impalpable powders, and pigments permanently suspended in a primary oil-in-water emulsion-type base or a complex system of hydrophilic cellulose derivatives, clays, and/or polymeric film formers, in which the gelling and suspending properties of the vehicle often are reinforced by a small amount of a Bingham-type plastic such as carbomer. 

There are a number of attributes of topical drug systems that may be classified as cosmetic that make patients more or less whHng to use their medications (comphant). These include the ease of appHcation, the feel of the preparation once it is on the skin, and the appearance of the applied film. Ideally, the appHcation should be undetectable to the eye and neither tacky nor greasy. Certain items, such as ointments and pastes, are of course intrinsically greasy, and suspensions of aU types tend to leave an opaque, easily detectable fHm. Thus, the extent to which the cosmetic features can be idealized is dependent on the nature and purpose of the dosage form. 

Different types of dispersions are encountered in industrial applications, the most common ones include solid/liquid (suspension), liquid/liquid (emulsions), gas/liquid (foams), liquid/solid (gels), and liquid/gas (aerosols). These dispersions are encountered in almost every industry in some form or the other during the preparation or as end product. Examples of industrial applications of dispersions include paints, dyestuffs, printing ink, paper coatings, cosmetics, ceramics, microelectronics, agrochemical and pharmaceutical formulations, and various household products. In the following sections, the characterization and properties of solid/liquid suspensions will be described. However, the same concepts would be valid for other kinds of dispersions also. 

In a similar manner to light, other types of radiation, e.g., electromagnetic waves in the X-ray domain, high-frequency electric fields, or acoustic waves, offer ways to monitor changes in composition and structure of suspensions. For instance, dielectric spectroscopy was used to investigate the moisture uptake and stability of cosmetic creams (Sutananta et al. 1996 Tamburic et al. 1996), and acoustic parameters (resonance frequency, attenuation, sound speed) were shown to correlate with sol-gel transition in suspensions of coUoidal silica (Senouci et al. 2001), as well as with the phase transition of renneted milk (Bakkali et al. 2001). 

Generic structures of most of the relevant petroleum-based cosmetic monomers used today are shown in Table 1. All of them are based on some type of carbon-carbon unsaturated (olefinic) double bond. Even the oxyalkylene monomers are simply activated olefinic materials. Understanding the nature of the polymerization reaction is not essential to understanding polymer functionality. However, most cosmetically relevant polymers are produced by some type of addition polymerization reactions, which are carbon-carbon bondforming reactions occurring across the unsaturated double bond of the monomers. These reactions can be initiated by free radicals, anions, or cations and can be mn in bulk, in solution, as suspensions, or even as emulsions. 

The main function of colour cosmetics, such as foundation, blushers, mascara, eyeliner, eyeshadow, lip colour and nail enamel, is to improve appearance, impart colour, even out skin tones, hide imperfections and produce some protection. Several types of formulations are produced, ranging from aqueous and non-aqueous suspensions to oil-in-water and water-in-oil emulsions and powders (pressed or loose). 

Water-soluble EMA resins and derivatives of these materials function very well as dispersants (Table A.3). For example, the amide-salt derivative exhibits excellent dispersant properties for pigments in waterborne synthetic latice systems. Dispersants for the coatings, rubber, leather, cosmetic, ceramics, photographic film, and agricultural field have been claimed for EMA resins. The linear derivatives are especially useful as dispersants and stabilizers for emulsion bead polymerizations. For example, EMA-type dispersants (emulsifiers) are very useful for PVC production. The resins also function well as macromolecular dispersants for the suspension copolymerization of a-olefins and aromatic vinyl compounds with MA. ... 

Conventional surfactants of the anionic, cationic, amphoteric and nonionic types are used in cosmetic systems. Besides the synthetic surfactants that are used in preparation of cosmetic systems such as emulsions, creams, suspensions, etc., several other naturally occurring materials have been introduced and there is a trend in recent years to use such natural products more widely, in the belief that they are safer for application. As mentioned above, polymeric surfactants of the A-B, A-B-A and BAn types are also used in many cosmetic formulations. 

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