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Questions about coacervation, complexing, polymers and salt thickening
To anyone who takes time out of their day to help me, I really appreciate it.
I would like to formulate using the following ingredients:
Confirmed: Sodium Lauryl Sulfoacetate (<3%), D-Panthenol (1.5%)Exploring: Caprylic Acid (for refatting, if that’s even possible), Magnesium Chloride
The goal of this, is to develop a shampoo that achieves a syrupy consistency with optimal lather, foaming capacity and without drying hair out too much. Additionally, I will be delivering multiple water soluble active ingredients not listed.
Magnesium Chloride has yet to have a salt thickening effect for me at any capacity. I’m wondering if this is because it’s a divalent salt. I have selected it due to it also delivering magnesium. Alternatively, I’m wondering if salt thickening is only applicable with high % formulations, like in most instances of SLS, and if it failed due to my usage of <3%. One idea someone mentioned, is that the addition of a amphoteric surfactant with both anionic and cationic properties, to both enhance the foam, and bring an oil such as caprylic acid into colloidal suspension, but I’m wondering if coacervation could actually be achieved like that.
The combination of Sodium Lauryl Sulfoacetate (SLSa), and Sodium Lauroamphoacetate formed solids that fell out of solution, and it seems to have poor quality control, so I’ve opted to not use it. I am not interested in Cocamidopropyl Betaine. Are there any other zwitterionic surfactants with a good reputation, that might work? Or very weak cationic surfactants that blend well with anionic surfactants like cocamidopropyl trimethyl ammonium chloride?
Another lingering question, is how do cellulose-based polymers like Hydroxyethylcellulose (HEC), and Carboxylmethylcellulose Sodium (CMC) compute in this equation? Do their charges bear any significance (HEC is non-ionic, and CMC is anionic). From both I note a deteriorating foam capacity as I increase the concentration relative to the SLSa. I notice from HEC, that my hair feels less clean and takes longer to dry, whereas with CMC, it feels more stripped. 1.3% seems to be the threshold at which an optimal texture is achieved for both, which is why I wanted to reduce their concentration and hence the salt thickening experiments (if I were to opt for CMC). Hydroxypropyl Methylcellulose also seemed to dissipate foam, and was more difficult to clean out of hair. HEC seemed to have minor benefits to foam.
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14 Replies
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There are way too many questions here for one post @formuoli so I’ll answer the first one. Coacervation may ONLY occur with an amphoteric/anionic surfactant blend and usually a nonionic builder or hydrotrope is needed too. CAPB and NaCocamphoacetate not working? Try a gemini ampho like disodium cocoamphodiacetate. BTW, multivalent salts do not thicken anything and NaCl will not thicken just any surfactant system either - a common error with newbie formulators in this forum - plus I can think of few mineral salts that will dry out your hair more than MgCl2. DO NOT use that.
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Thanks so much for the response man. I think I figured out the coacervation but with a different chemical. What I really want to know more about though is what you said about multivalent salts not working as thickeners, can you please explain why that’s the case? I’ve heard from others that Sodium Lauryl Sulfoacetate can be salt thickened, but it was anecdotal - though I believed it since it’s an anionic surfactant. But people have also said that Magnesium Chloride can effectively salt thicken anionic surfactants. So what’s the truth? Does salt thickening even work if your total surfactant concentration is <3.5%?
And on the topic of coacervation, which I’m assuming you’re knowledgeable of, if I have indeed created a coacervate, is its purpose limited to silicones or polyquats? I read that when excessive water falls upon the coacervate, it releases these agents to serve as conditioners, thus making a “2 in 1” shampoo possible. What if instead I added D-Panthenol, or Hydroxyethylcellulose - do other conditioning agents or polymers not count? Thanks.
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I’m definitely not a coacervation expert but I’d expect D-panthenol not to deposit very well because it’s so water soluble. From my understanding (hopefully someone can educate me if any of the below is wrong), you may get some interaction with a charged surfactant-uncharged polymer, but the systems which are more typically used and have most dramatic results are oppositely charged polymer-surfactants systems. So a cationic-functionalized cellulose could perform better, and as a bonus if you use a positively charged polymer you should get better binding to keratin of the hair which is negatively charged. Also, adding salt affects the coacervate region of precipitation (generally decreases coacervation because of salt shielding- it also changes when the system ppts). These systems are complex and there’s lots of literature on this topic (you can look at anything by Goddard or Ananthapadmanabhan)
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What cationic cellulose do you know of that I can experiment with?
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The oldest one Dr Goddard (the father of coacervation) and later P&G used and studied: polyquaternium-10. It’s been widely researched for decades, especially coacervates with SLS and SLES.
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I’m looking to minimize film.
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Hi. Can you be a bit more specific?
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Since my product will be used on thin hair, creating a film can cause it to stick together and thus look even worse vs a more dry look. Keeping it light is important for my design philosophy
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Coacervates are neutral in nature, so I wouldn’t expect hairs to stick together because of the film. What you could experience is overdeposition, but that depends on your coacervate design and the performance of the shampoo to remove most of the coacervate deposited. You might benefit from this reading: https://www.amazon.com/Conditioning-Agents-Cosmetic-Science-Technology/dp/0824719212
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Hey, did you see my question?
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Your question was answered by ketchito and their response is a great starting point if you are serious about trying to use coacervation technology
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Salt thickening works only with monovalent species like NaCl, not Mg++, and nothing will be much help when the surfactant concentration is that low. You’ll have to use an acrylic rheology thickener like Synthalen W600 for that. Coacervation is much too complex a topic for this. I suggest reading Des Goddard’s compilation “Principles of Polymer Chemistry in Cosmetics and Personal Care” and study the chapters Des authored on this.
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What chemical(s) compose Synthalen W600?
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Hey, are you seeing this?
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