Polysorbate 20 troubles....

I did an experiment between different ratios of polysorbate 20, water, essential oils, and plant oils. The ratios were..

1: water-------------94%                             
    polysorbate 20 ----3%
    essential oils------1%
    plant oils---------2%

2: water -----------91%
    polysorbate 20----6%
    essential oils------1%
    plant oils---------2%

3: water------------88%
    polysorbate 20-----9%
    essential oils-------1%
    plant oils----------2%

I didn't heat any of this mixture up. I added the oils and polysorbate into a bowl and mixed that up first the slowly poured into the water while stirring. then I put it into a spray bottle and shook it up.

They all seemed to emulsify but there's this cloudy ring at the top of the mixture that will go away when shaken but goes back to having an unattractive cloudy ring at the top of the formula in just a couple minutes. The rest of the formula is a murky yellow color as well and I don't think that's normal. Any suggestions?

Comments

  • PharmaPharma Member, Pharmacist
    A 3:1 ratio of Tween 20 to oils is limit, might work for some but won't for others. The two lower ratios are +/- bound to fail, you could probably make emulsions/creams but not the desired micellar solutions with them.
  • will a 1:1 ratio do it then? Will it also work with the plant oils and not make the solution cloudy?

  • Too much oil. Poly 20 isn’t particularly strong. It somewhat works with less than 1% of EOs (depending on the oil). PEG-40 Hydrogenated Castor Oil is better solubilizer.
  • @Pharma I am currently experimenting with Polysorbate 20 as EO solubilizer in a toner. Just yesterday I did a seris of Knock-out experiments and ended up with only water, Polysorbate 20 and palmarosa essential oil. Even with 6:1 ratio it was still cloudy. I will try and see what happens with other EOs these days. May I trouble you for a brief explanation of that 3:1 limit as recommended concentration of Polysorbate 20 is usually up to 10%. What am I missing here?
  • PharmaPharma Member, Pharmacist
    Meemcha said:
    ...May I trouble you for a brief explanation of that 3:1 limit as recommended concentration of Polysorbate 20 is usually up to 10%. What am I missing here?
    That's just a rule of thumbs. In order to be transparent or at least translucent, emulsion droplets have to be in the form of small micelles rather than droplets. Empty polysorbate 20 micelles contain only about 80 surfactant molecules. Essential oil molecules need to be dissolved between the lipophilic tails rather than forming a core as is the case with 'standard' emulsions. Else, the droplets become too large and the solution turns milky. That's why the ratio of EO to surfactant is a lot small than the ratio of oil phase to emulsifier in a common cream/lotion.
    Furthermore, larger droplets tend to cream whilst small micelles are small enough to be subject to brownian motion which counteracts/supersedes gravity.
  • Polysorbate 20 and/or PEG-40 HCO often need 5x the oils weight.
    Only about Poly Suga Mulse D9 works fine at 3x.
  • Pharma said:
    Meemcha said:
    ...May I trouble you for a brief explanation of that 3:1 limit as recommended concentration of Polysorbate 20 is usually up to 10%. What am I missing here?
    That's just a rule of thumbs. In order to be transparent or at least translucent, emulsion droplets have to be in the form of small micelles rather than droplets. Empty polysorbate 20 micelles contain only about 80 surfactant molecules. Essential oil molecules need to be dissolved between the lipophilic tails rather than forming a core as is the case with 'standard' emulsions. Else, the droplets become too large and the solution turns milky. That's why the ratio of EO to surfactant is a lot small than the ratio of oil phase to emulsifier in a common cream/lotion.
    Furthermore, larger droplets tend to cream whilst small micelles are small enough to be subject to brownian motion which counteracts/supersedes gravity.
    Thank you! After I posted this today, I did a quick test with Ho wood essential oil. Same thing as with Palmarosa, I got a clear solution at 9:1 ratio. But this wasn't with pure water, I had 20% lavender hydrosol as well. PEG-40 HCO, on the other hand, did a wonderful job at 5:1 ratio. 

    Gunther said:
    Polysorbate 20 and/or PEG-40 HCO often need 5x the oils weight.
    Only about Poly Suga Mulse D9 works fine at 3x.
    I regularly use PEG-40 HCO at 4 or 5:1 ratio and works wonderfully. I actually started this PS 20 quest because I am constantly seeing recommendations for 1:1 ratio for solubilization and it tickled me because my experience said differently and I wanted to check if I was missing something. I wasn't as PEG-40 HCO really beats it in clear products.

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