Silicones in Hair Care: Making Innovative Solutions Possible

Posted: May 23, 2007

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The solubility parameters of PDMS are significantly different from those of water and many organic materials. PDMS polymers are highly water resistant, and except for certain low molecular weight species, they are incompatible with organic ingredients. The solubility characteristics of these materials can contribute to barrier effects and substantivity; the same properties make them effective agents in reducing the tackiness of formulations.

PDMS is typically used in opaque products, where it can be emulsified to provide increased formulation flexibility. Various viscosities of PDMS can be blended to provide specific formulation attributes such as evaporation rates, spreading qualities and sensory benefits.

Cyclic polydimethylsiloxanes or cyclomethicone fluids are characterized by ring structures typically containing three to six Si-O groups per ring. They reduce wet combing force and provide transient gloss to hair, without leaving residue or buildup. Because of their volatility, the effects of cyclomethicones are transient, a significant advantage in products designed for daily use. They help decrease drying time, which is helpful because the ongoing combination of combing and dryer heat are damaging to hair. Volatility also allows these materials to be used as carriers to facilitate deposition and spreading of active ingredients. Cyclomethicone fluids are compatible with a wider variety of ingredients than linear PDMS, and they can serve as good carriers for high molecular weight silicones that would otherwise be difficult to handle.

Silicone gum/fluid blends are composed of very high molecular weight PDMS supplied in low to medium viscosity linear PDMS fluid or cyclics for ease of formulation and improved compatibility. These materials offer a high level of substantive conditioning while imparting a soft, dry and lubricious feel to hair. They can also be used for their thickening effect in water-and-oil systems.

Phenyl trimethicone is based on linear PDMS with the addition of phenyl groups. The result is a higher refractive index, which is used to increase apparent shine on hair, typically in styling products or cuticle coats. Phenyl trimethicone adds softness with low residue and exhibits greater compatibility with organic ingredients for ease of formulation.