Silicone surfactants cosmetic applications

Industrially, silicone surfactants are used in a variety of processes including foam, textile, concrete and thermoplastic production, and applications include use as foam stabilisers, defoamers, emulsifiers, dispersants, wetters, adhesives, lubricants and release agents [1]. The ability of silicone surfactants to also function in organic media creates a unique niche for their use, such as in polyurethane foam manufacture and as additives to paints and oil-based formulations, whilst the ability to lower surface tension in aqueous solutions provides useful superwetting properties. The low biological risk associated with these compounds has also led to their use in cosmetics and personal care products [2]. 

A significant amount of information regarding the uses of silicone surfactants is still found primarily in the patent art, but the major applications have recently been reviewed in journals. Silicone (or siloxane) surfactants are also called silicone polyethers (SPEs), polyalkylene oxide silicone copolymers, silicone poly(oxyalkylene) copolymers and silicone glycols. The International Cosmetic Ingredient Nomenclature and the Cosmetic, Toiletry and Fragrance Association (CTFA) adopted name is dimethicone copolyol. 

Silicone-based materials are an important class of polymeric surfactants that are commonly used in the cosmetic industry. They consist of poly(dimethyl siloxane) (PDMS) that is modified by incorporation of specific groups for special applications. For example, dimethicone copolyol (used as emulsifier or dispersant) is typically a copolymer of PDMS and polyoxyalkylene ether. Aminofunctional silicones provide excellent hair-conditioning benefit. Polyether-modified silicones, including terpolymers containing an alkyl or polyglucoside moiety, are very effective emulsifiers for water-silicone emulsions. These silicone surfactants act as defoamers, depending on the amount and type of glycol modification. They are also used to reduce skin irritation. 

Methyl chloride is also used to make intermediate feedstock for production of silicone fluids, which are commonly used as lubricants, release agents, and surfactants, as well as in cosmetics, paper coatings, and some medical applications. 

Silicone polyethers are important nonionic surfactants that are also used in cosmetics and household chemistry. However, their most important application is the manufacture of polyurethane foams, both rigid and flexible ones. There are no substitutes for them and their role eonsists in the facilitation of mixing of foam components. They prevent from the formation of large bubbles, facilitate the control of fluidity of liquid mixture (that expands due to the bubble growth), and they enable accurate control of time and degree of foam opening. 

The ability of SPEs to form vesicles, which are structurally comparable to liposomes, has opened a wide range of possibilities for the incorporation of active ingredients. Silicone vesicles can have a diameter from about 0.05 to 1 micron and an internal volume of 10 pm. The membrane thickness of these vesicles is about 3 to 4 nm [56]. The main application of siloxane-based surfactants vesicles is in cosmetics. For example, using silicone vesicles, hydrophilic and hydrophobic active substances can be separated and protected from each other, thus reducing for example skin irritamw. Active delivery systems include non-aqueous emulsions of polyols in silicone fluids, multiple-phase emulsions, and polar solvent-in-oil emulsions. 

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