Silicones are ubiquitous ingredients widely used in personal-care products. They are one of the few ingredients commonly used in formulations that can create a “wow factor,” or a readily noticeable sensory effect.
It is estimated that during the past 10 years, over 50 percent of all new products introduced globally contained at least one silicone. Silicones were first commercialized in the 1940s in the United States by Dow Corning and were produced from intermediates synthesized from silicon metal. Silicon is the second most abundant element found on the earth and is produced by reacting silica with carbon in an electric arc furnace.
Silicones are defined as compounds that possess at least one silicon/carbon bond and have a siloxane linkage (Si-O). They are made up of alternating silicone and oxygen atoms and may carry end or pendant groups that can be functionalized. Silicones have unique surface active properties due to their high bond angle, bond length and low rotational energy of the siloxane bond compared with carbon/oxygen or carbon/carbon bonds.
There are three basic types of silicone: fluids, resins and elastomers. The most common silicones are dimethicones or polydimethylsiloxanes, which are derived from the hydrolysis of dimethyldichlorosilane. When dimethicone contains a terminal hydroxyl group it is referred to as a dimethiconol.
Dimethicone fluids are extremely heat and chemically stable, have a low glass transition temperature and elastic modulus, are very hydrophobic and non-polar, and have a low surface tension and coefficient of friction. Dimethicones are commercially available from .65 centistoke (cSt) viscosity up to 1,000,000. Typical personal-care applications include two-in- conditioning shampoos (combined with a cationic polymer) to reduce the tackiness and soaping of skin-care formulations while providing a silky smooth skin feel.
Typically, >100,000 cSt fluids are referred to as gums and used in shampoos and conditioners. The most efficient feel-modifying, tack-reducing silicones are gum blends comprised of 85 to 90 percent of a low-viscosity carrier and 10 to 15 percent gum. Carriers used include .65-10 cSt dimethicone, cyclopentasiloxane, isoparaffins and isononyl isononanoate.
Cyclopentasiloxane (D5) is a volatile cyclic silicone that is widely used as an emollient in formulations to provide temporary emolliency with a non-greasy skin feel. Other fluids used in personal care include organofunctionals, which include amine, phenyl, alkyl methyl methicones and alkyl dimethicones.
Amine-modified silicone fluids contain pendant diamino or diaminopropyl groups. They are available with different amino concentrations, viscosities, and are more substantive and conditioning than dimethicone gums. Typical uses include shampoos and conditioners. Most organofunctional fluids provide improved organic compatibility and are more occlusive than their unmodified counterparts. Phenyl fluids also have a high refractive index, making them useful to enhance hair shine.
Recommended Dimethicones:
- Xiameter PMX-200 Silicone Fluid 5.0 cSt (Dimethicone) by Dow Corning a 5 cSt fluid
- Element 14 PDMS 10 (Dimethicone) by Momentive Performance Materials, a 10 cSt fluid
- DM-Fluid-350 cs (Dimethicone) by Shin-Etsu Silicones of America, a 350 cSt fluid
- DM-Fluid-100000 cs (Dimethicone) by Shin-Etsu Silicones of America 100K cSt fluid
- Belsil® DM 300000 (Dimethicone) by Wacker Chemical Company, a 300K cSt fluid
Recommended volatile fluids:
- Dow Corning® Q7-9180 Silicone Fluid (Dimethicone) by Dow Corning, a .65 cSt fluid
- DM-Fluid-A-1 cs (Trisiloxane) by Shin-Etsu Silicones of America, a 1 cSt fluid
- Xiameter® PMX-0245 (Cyclopentasiloxane) by Dow Corning
Recommended gum blends:
- Xiameter® PMX-1501 Fluid (Cyclopentasiloxane and Dimethiconol) by –Nexeo Solutions, contains 15% of a high molecular weight dimethiconol gum in cyclopentasiloxane
- Xiameter® PMX-1413 Fluid (Dimethicone) by Nexeo Solutions, contains 14% of a high molecular weight dimethicone gum in 5 cSt. dimethicone
Recommended organofunctional fluids:
- KF-8015 (Aminopropyl Dimethicone) by Shin-Etsu Silicones of America), 50,000-100,000 cSt grade
- Dow Corning® 2-8566 Amino Fluid (Amodimethicone) by Dow Corning, 3000 cSt, .875% nitrogen, can formulate clear conditioning shampoos
- KF-8020 (Dimethicone and Aminopropyl Dimethicone) by Shin-Etsu Silicones of America, 20% aminopropyl dimethicone in a 20 cSt dimethicone
- Dow Corning® 556 Cosmetic Grade Fluid (Phenyl Trimethicone) by Dow Corning ,thanol soluble
- KF-54 (Diphenyl Dimethicone) by Shin-Etsu Silicones of America, a 400 cSt fluid with a refractive index of 1.505
- KF-54HV (Diphenyl Dimethicone) by Shin-Etsu Silicones of America, the highest cSt grade (5000 cSt)
- SF1555 (Bis-Phenylpropyl Dimethicone) by Momentive Performance Chemicals
- Dow Corning® ST-Wax 30 (C30-45 Alkyl Methicone) by Dow Corning, melting point 60°C, good organic compatibility
- SF1642 (C30-45 Alkyl Dimethicone) Momentive Performance Chemicals, melting point 60°-70°C
- Belsil® SDM 5055 VP (Stearyl Dimethicone) by Wacker Chemical Corporation
Interested in learning more about silicones? Read Silicones: The Formulation Wow Factor, Part 2
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it very helpful for me
Very well written explained George …my compliments !!