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  • Hydrophobically modified polymers

    Posted by Pharma on December 19, 2022 at 7:56 pm
    Hello community,
    Does anyone know where I might get DIY quantities of a hydrophobically modified polymer or what’s often called ‘associative thickener’?
    To make things complicated: the polymer should be nonionic (salt tolerant), as ‘natural’ as possible (I’m trying to avoid PEG, PPG, acrylates, silicones, and polyurethanes if/where possible), and should, by preference, be an ABA triblock polymer (hydrophobic-hydrophilic-hydrophobic).
    As alternative, alkyl graftet polymers would be okay too (thinking of Natrosol Plus 330 by Ashland… but who offers it at very small MOQ and does a non-ethoxylated version exist?).
    I know that Sepimax Zen is said to be a hydrophobically modified polyacrylate… however, I would like to know what the chemical structure of polyacrylate-6 crosspolymer actually looks like (at least more or less) but am drawing a blank on Google. As said, I’m trying to avoid acrylates if possible also because I know that many which are claimed to be electrolyte tolerant are so only if compared to traditional carbomers. Alas, Sepimax Zen is all I’ve got so far.
    Pharma replied 1 year, 5 months ago 3 Members · 4 Replies
  • 4 Replies
  • HAL49

    December 20, 2022 at 2:45 am

    Hi Pharma , 

    May I ask what function do you need it to perform ?

    Right now I can’t think of anything what all that requirements but maybe I can came up with options depending on the functionality, do you need it as a salt tolerant thickener? 

  • Pharma

    December 20, 2022 at 8:37 am
    Not sure if explaining which function it needs to perform would actually help… because the function is on a molecular level (the visible/measurable results from that, such as increased viscosity, aren’t my goal but are merely logical consequences).
    I’m working with quite high levels of electrolytes and hence, most things I use should be salt tolerant to a degree where one might call it even ‘salt ignorant’.
    So, what it needs to do is stick one hydrophobic part A into one oil droplet and the other end into another oil droplet and bridge it at distance B. It should help to increase stability of low surface tension emulsions such as microemulsions and near-microemulsions or, respective, emulsions close to HLD 0. This would likely also increase viscosity as a welcome result but for that outcome, I could use other gelling agents as well. It might further help to stabilise non-crystalline lamellar networks and o/w HIPE gels (depending on chain length B ). But that’s purely speculative but something I would, one day, like to try out.
  • chemicalmatt

    December 21, 2022 at 7:51 pm

    @Pharma virtually all of the acrylic associative thickeners, Seppimax ZEN and Polyacrylate-6, -11, etc. included, are crosspolymers. They all have crosslinked 3D structures once alkali-swelled in water. Also share nearly zero tolerance for electrolytes as you’ve surmised, and that includes ZEN and don’t get me started on Seppic claims to the contrary. (grrrr..) Your options are then limited as you’ve also surmised, since virtually all HASE thickeners are acrylics, even Polyquaternium -37, and -32. The system you describe is a Pickering emulsion if not mistaken, so why not work with cellulose and its gum blends? Add a little surfactant and you may get where you need to go with electrolytes included.   

  • Pharma

    December 21, 2022 at 8:49 pm
    @chemicalmatt Thanks for the feedback!
    Nope, it’s not a Pickering emulsion. These work with particles, not soluble things.
    I would like to have a polymer ‘barrier’ around the oil phase (a bit like in a Pickering emulsion) but with it being anchored in the oil phase. By preference a linear entity spanning from one oil ‘droplet’ to the next. This can increase viscosity of low viscosity emulsions without increasing the water phase’s viscosity or rather independently of the viscosity of the water phase which obviously increases to some degree. Alternatively, it forms a more stable and less HLB or HLD dependent steric hindrance when each end sticks in the same ‘droplet’ forming a loop with the hydrophilic middle part. A cross-linked polymer or comb like hydrophobically grafted linear polymer is the plan B (these certainly have additional pros).
    A workaround might be the combination of an anionic polymer with a cationic emulsifier but the effective ratio between the two is very narrow and it’s a highly electrolyte sensitive and pH dependent system.

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