Silicones in Hair Care: Making Innovative Solutions Possible

Posted: May 23, 2007

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Amodimethicone fluids are recognized for their ability to provide deep conditioning. They are typically based on the replacement of some methyl groups on PDMS with primary and secondary amine groups. This amine functionality results in attraction to the negative, proteinaceous surface of hair followed by cross-linking to form a substantive film, a mechanism that can be used to provide targeted deposition without buildup.

Because of their larger organic groups, amodimethicone fluids can be easier to emulsify into surfactant systems, and they can be useful for making clear shampoos. They can also be used in rinse-off conditioners, semi-permanent and permanent colorants and leave-in conditioning treatments (e.g., detanglers, cuticle coats, hot oils, hair masks and mousses). In addition to softness, smoothness, reduced fly-away and faster drying time, amodimethicone fluids can be formulated to provide color protection for dyed hair and thermal protection from excessive heat from hair dryers, curling irons and other styling devices.

Alkylmethicones are based on the replacement of some methyl groups on PDMS with alkyl chains, resulting in a family of silicone-hydrocarbon hybrids. With variations in viscosities, melt temperatures and rheological characteristics, these materials can help overcome some of the issues related to incompatibility of PDMS with organic materials and water. Alkylmethicones also offer improvements in substantivity and moisturization. They can be used in water-in-oil emulsions to add body and aid stability without contributing negative aesthetics.

Silicone polyethers are a family of water-soluble or water- and alcohol-soluble silicone materials that can be used to reduce aqueous surface tension. The addition of oxyethylene substituents on the siloxane backbone increases hydrophilicity, while the polypropoxylated portion can be added to increase hydrophobic characteristics. The resulting nonionic surfactants reduce the surface tension of aqueous systems and allow good wetting of hair while enhancing foaming.

In addition to acting as emulsifiers or coemulsifiers, silicone polyethers can be used as resin modifiers to aid curl retention. They provide a mild lubricating effect, and some can be incorporated into shampoos and similar products to help reduce eye irritation from organic surfactants or to enhance foam. These materials are commonly used in shampoo formulations designed for daily use, where they provide light to medium conditioning with reduced fly-away. Because they are compatible in aqueous systems, silicone polyethers can be used in clear shampoos. Formulation is easy for both cold and hot processes, without the need for pre-emulsification, solubilizers or suspending agents.