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Cetearyl alcohol. Emulsifier or not?
I don’t understand why some sources quote cetearyl alcohol as an emulsifier. According to the HLB values given by various sites, cetearyl alcohol is not listed as an emulsifier but instead as a lipid.
I’m looking at designing a new mamey oil cream. I can’t find an HLB value for mamey but it is similar to argan so I’ll assume it is around 11. The other lipids are stearic acid (HLB 15) and polydimethylsiloxane at 1000 cs viscosity. I can’t find the exact HLB for the silicone but it is probably around 11.So… to bother trying cetearyl alcohol at all as an emulsifier when the HLB system doesn’t regard it as such? According to my HLB calcs I need about 82% of Tween-80 and 18% glyceryl monostearate because the required HLB is 13. -
14 Replies
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According with Swift is not:
http://swiftcraftymonkey.blogspot.com/2013/05/weekend-wonderings-cetyl-alcohol-really.html -
Swift was talking about cetyl alcohol, not cetearyl.
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Sorry, here is the cetearyl alcohol reference from Swift, perhaps is used more as a co-emulsifier
http://swiftcraftymonkey.blogspot.com/2010/10/asidecetearyl-alcohol.html -
Cetearyl is just a mix of cetyl and stearyl alcohols. Neither emulsifies.
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Thanks Bob. That’s what I thought. In that (second) comment by Swift she refers to cetyl as an emulsifier but it certainly isn’t.
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There’s a Dow Corning silicone emulsifier that’s pretty amazing…
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I usually think of “emulsifiers” as molecules that are active at the water-oil interface. Materials like Cetyl alcohol, stearyl alcohol, cetearyl alcohol, etc. support emulsion stability typically by increasing steric hindrance and often times get lumped in as “emulsifiers” themselves (even though they are not active at the water-oil interface).
Also, @Belassi I’m not sure what kind of silicone you are using, but I’ve found that applying the HLB system to silicones can be pretty hit or miss. However, I have had more luck with low HLB emulsifiers than with high HLB one’s for dimethicone in particular.. -
@Iaskedbetter: Thanks a lot for that note about silicones. I have found the same thing - the last thing I designed with a silicone in it was a conditioner, and I had to experiment with the range of emulsifiers I have before it would stop separating. It took quite a lot of work.
The one I intend using is Polydimethylsiloxane fluid 1000, so called because it is quite viscous, it has a viscosity of 1,000 Cs. How much emulsifier would you use for say 1% of that? -
theoretically cetyl alcohol is emulsifier cause it has both hydrofilic and hydrophobic groups, but in experimental it is emulsifier via thickining effect(not being active in surface). In my opinion every material which helps in the stability of an emulsion is emulsifier. some are active in interface( correct and scientific explanation of an emulsifier) such as GMS and some are thickening(like cetyl alcohol).
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I was wondering if there is a strict definition of what an emulsifier is, are all molecules with hydrophobic/hydrophilic groups emulsifiers? And with nasrins definition “every material which helps in the stability of an emulsion is emulsifier” - also carbomer would be an emulsifier…
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As I studies in some papers all emulsifiers have hydrophobic/hydrophilic groups but vise versa isn’t always valid.
“when an emulsifier is added to the system, the droplets remain dispersed, and a stable emulsion is obtained” http://www.emulsifiers.org/ViewDocument.asp?ItemId=11& cetyl alcohol does this so why not be an emulsifier? when droplet are in a viscose condition are they have any potential to seperate? these are not overal laws ………..and I dont know maybe I am wrong
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My dictionary of Chemistry states that also carbon black is an emulsifier.(or actually emulsifying agent, not to be confused with a machine producing an emulsion)
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Both Cetyl Alcohol and Cetearyl Alcohol (a mix of stearyl and cetyl alcohol) are solid “fatty alcohol” waxes. These can be made from their respective fatty acid counterparts - Cetyl Alcohol (C16) from palmitic fatty acid, and Stearyl Alcohol (C18) from stearic fatty acid. They technically, scientifically, have ZERO HLB value because they cannot emulsify anything. In fact they each have an HLB requirement of around 15, which means by definition they cannot emulsify if they require an emulsifier to emulsify them. Even a Low HLB emulsifier has some ability to draw water into oil (hence why they are used in water-in-oil emulsifiers, and need to be combined with a high HLB emulsifier in order to produce an oil-in-water emulsion). That being said, they are often used as an emulsion “STABILIZER” because the long carbon chain length of fatty alcohols can help hold everything together better at the interface, particularly with a more unstable emulsion. Because they have the quality, they are often indicated as “co-emulsifiers” which can cause confusion for many people new to all of this.
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cetyl alcool and cetearyl alcohol are both co-emulsifiers. They change the curvature of the surfactant at the interface Oil/water.
i’m wondering by which mechanism the cetearyl alcohol is thickening the continuous phase?
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