Why O/W polymers are added to W/Si emulsions?


Hello All,

I have some modest experience with O/W products and have an idea how o/w polymers such as Sepinov EMT 10 or Aristoflex AVC work.

Recently I started exploring W/Si world and had to forget all rules I learnt before. For example O/W polymers don’t really like electrolytes (with some exceptions), while in W/O they are must have for stability. I also heard on the institute of personal care science channel that O/W polymers (I think they particularly mentioned xanthan) should not be used in W/O systems because they somehow break the emulsion.

On the other hand there is Seppic’s Geltrap (that is utterly unstable) that mixes Easynov with Sepiplus 400. Seppic however doesn’t recommend adding electrolytes for an obvious reason (they will break gelled water phase). I tried to apply geltrap’s logic to other materials. I mixed Aristoflex AVC with PEG-30 Dipolyhydroxystearate  W/O HIPE emulsifier and all I got is a greasy mess with W/O properties that separated the next day. I thought it must be a good idea because Easynov is a combination of PEG-30 Dipolyhydroxystearate and Fluidanov. Apparently it doesn’t work.

Apologies for the long introduction, but how can this be explained:

Water, Cyclopentasiloxane, Ethylhexyl Methoxycinnamate, Cyclohexasiloxane, Glycerin, Isododecane, Butylene Glycol, SD Alcohol 40 (Alcohol Denat.), Lauryl PEG-9 Polydimethylsiloxyethyl Dimethicone, Polyglyceryl-4 Isostearate, Cetyl PEG/PPG-10/1 Dimethicone, Hexyl Laurate, Disteardimonium Hectorite, Nylon-12, Glycoproteins, Panax Ginseng Root Extract, Equisetum Arvense (Horsetail) Extract, Glycine Soja (Soybean) Oil Unsaponifiables, Ilomastat, Ursolic Acid, Hydrogenated Lecithin, Retinyl Palmitate, Hydrolyzed Soy Protein, Ascorbyl Palmitate, Plankton Extract, Camellia Sinensis Leaf Extract, Carnosine, Sodium Hyaluronate, Olea Europaea (Olive) Oil Unsaponifiables, Dimethicone/PEG-10/15 Crosspolymer, Triticum Vulgare (Wheat) Germ Oil Unsaponifiables, Algin, Hydrolyzed Malt Extract, Polymethyl Methacrylate, Phospholipids, Tocopheryl Acetate, Caprylic/Capric Triglyceride, Octyldodecanol, Pollen Extract, Disodium Stearoyl Glutamate, Acacia Senegal Gum, Magnesium Sulfate, Squalane, Dipropylene Glycol, Trihydroxystearin, Serine, Acrylates Copolymer, Aluminum Starch Octenylsuccinate, PEG-8, Diphenyl Dimethicone, Polysorbate 60, Cellulose Gum, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Sodium Phosphate, Sucrose, Dimethicone/Vinyl Dimethicone Crosspolymer, Xanthan Gum, Caprylyl Glycol, Aluminum Hydroxide, Propylene Glycol, BHT, Sodium Laureth Sulfate, Fragrance, Butylphenyl Methylpropional, Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde, Hydroxycitronellal, Linalool, Citronellol, Alpha-Isomethyl Ionone, Geraniol, Methylisothiazolinone, Phenoxyethanol, Methylparaben, Ethylparaben, Propylparaben, Butylparaben, Titanium Dioxide, Iron Oxides, Iron Oxides, Iron Oxides

I can see several W/Si emulsifiers on the top of the list mixed with what must be Seppic’s Simulgel NS.

Does anyone know what is the purpose of O/W gelmaker in a W/Si system?

Thanks in advance!


Comments

  • Forgot to mention the LOI above is a foundation by La Prairie. 
  • PharmaPharma Member, Pharmacist
    La Prairie, I thought it must be something fancy and expensive :smiley: .
    Seppic says Simulgel NS is a gelling agent for all sorts of oil phase and silicones are also considered oils.
    I suppose La Prairie uses different pre-blends for their creams to facilitate production. I mean, who's gonna weigh 100 ingredients one by one? Could well be that Simulgel NS is part of such a mix (??).
    BTW disteardimonium hectorite and aluminum starch octenylsuccinate are oil gelling agents too. Hydrogenated lecithin and phospholipids can also be used to gel oil and may show synergism with unsaponifiables. Or they're just in there because of aforementioned blends.

    OT:
    - Why isn't ilomastat considered a drug?
    - Probably a layman's question: What does Plexiglas do in that foundation? Microplastic particles? What for?

  • Yes, it is quite an expensive and quite nice product. I suspect it’s simulgel NS. But even if it’s just Sepinov EMT 10 separately, I really wonder why is it added to W/Si system...
  • PharmaPharma Member, Pharmacist
    ...I really wonder why is it added to W/Si system...
    If that's the only thing you wonder why it's in there... :smile:
    Check THIS out: They say it's compatible with silicones.
  • I guess I must try that experiment again... so based on your knowledge of w/o systems, do you know any reason not to thicken water phase?
  • PharmaPharma Member, Pharmacist
    Yes. Well, as pharmacist we kinda learned that if you knew your job, then you knew how to make an emulsion stable. Thickening water phase wasn't exactly called that but treated as such; a way of "cheating" for those who didn't manage a make their emulsion stable because they didn't know how to calculate HLB and the like.
    Now when I started making cosmetics, things all of a sudden look different. You don't inject emulsions into patients anymore, creams are no longer applied for transdermal drug delivery, and you don't put a note on it "Keep in fridge. Exp.: 1 Months from now". Customers buy cosmetics because of hopes and dreams, use them for fun, want them to be fine under the most extreme/stupid conditions, and worst of all, they want an awesome looking/feeling/smelling/forever-rejuvenating magical potion. You have to lie and cheat the shit (*ups*) out of it just to get a step closer to that expectation. And that was the point where I learned that it's absolutely okay to thicken water phase. Nonetheless, I still don't really like water gelling, gelling oil on the other hand is absolutely fine, though. Likely because back in the day we thought of it differently (that's why I prefer the expression "state of error" rather than "state of knowledge").
  • @Pharma, I hope you don't mind if I pick your brain on the HLB.

    When I just got into formulation I was calculating HLB for O/W emulsions. Many professionals on this forum think that if you use commercial blend of emulsifiers like Arlacel 165 you don't need to bother. Also HLB system has limitations (applicable to non-ionincs only, doesn't specify how much of emulsifier to use etc). So, I stopped calculating it. Which doesn't really impact the stability as I dump tons of stabilisers, polymeric emulsifiers etc to the most of my formulas. 

    Now back to W/O. Most of oils have pretty high HLB. Whatever I do, I end up with average required HLB around 10. The only way to have it low is to use pure dimethicone or mineral oil. My W/O emulsifiers are all below 6. I really don't get how to solve this. Also, if you look at many commercial W/O products they do make W/Os with high required HLB oils (esters) somehow. Low HLB oils tend to be greasy. Making W/O with greasy oils is a terrible idea..
    Am I missing anything?
  • PharmaPharma Member, Pharmacist
    Short version:
    Yes, you miss something. HLB values are, except for PEG-acyl ethers, either empirical or use modern fancy mathematical models. HLB is basically caused by shape and lipophilic-hydrophilic volume ratio and not just a molecular weight ratio and it translates to interfacial curvature or an angle (180° being straight e.g. intermediate HLB = not micelles/inverse micelles but lamellar structure).
    HLB requirement of oils is usually the HLB required to form a stable o/w emulsion. You rarely find HLB requirements for w/o emulsions (these are lower: beeswax o/w = 12, w/o = 4, lanolin is 10 and 8, octyldodecanol has 11 and 6, liquid paraffin has 10 and 4, respectively, and that's about all I could find).
    Midrange HLB or no interface curvature makes the system highly dependent on composition of the two phases and co-emulsifiers and fatty alcohols to tip curvature to one or the other side. Mixing different emulsifiers and fatty alcohols leads to self-assembling, like black and white tiles forming a chess board only that the tiles can have many shapes, triangular, pentagonal, hexagonal and mixtures thereof like you see on a football. Given that such an emulsion is usually a mix of different types like lamellar, hexagonal, cubic, and micellar phases makes it easy for such a system to distribute excesses of on or the other emulsifier to another part of the emulsion or, like with monoglycerides and fatty alcohols, simply have them dissolve in the oil. A pure PEG emulsifier on the other has no choice other than sticking to the interphase and hence, the emulsion works or breaks.

    I let you meditate on that and am going sleepy-sleepy. Nighty-night!
  • Different HLB for w/o and o/w....... My brain exploded when I read it but now many thing made sense. You are right, it's almost impossible to find w/o HLB tables.

    I would really appreciate if someone can share.
  • PharmaPharma Member, Pharmacist
    ...
    I would really appreciate if someone can share.
    Me too.
    Although w/o HLB requirements are usually useless because (as mentioned above) most w/o emulsions aren't inverse micelles but a mixture of other w/o systems which don't "comply with the HLB system".
    If you look closely, the values I found are from "old/traditional" ingredients back from the day when "things were different" (when we thought that stable o/w and w/o emulsions are always micellar systems).
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