Incompatibility/Browning with Arcylate Copolymer

been using Cosmedia ATC for many formulations never seen issues until recently. ingredients are:

Acrylamide / Sodium Acrylate Copolymer (and) Paraffinum Liquidum (and) Trideceth-6

We've put it with small (really small-0.05%) amounts of ascorbic acid and ferulic and we see over time or exposure to high temps a disturbing browning. has anyone used this thickener or one like it before, or have any idea what chemistry is causing this?


  • It is likely you have oxidation reaction with ascorbic acid and Ferulic acid at high temperature and probably  slowly with time in storage at lower temps.
  • Bill_TogeBill_Toge Member, Professional Chemist
    agreed: ascorbic acid is notorious for browning in water-based formulations
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • EVchemEVchem Member
    Even with such small amounts? It showed an extreme change in color, from a near pure white to a very tan brown (From what I've seen with ascorbic before, the oxidation is usually more of a yellowing in color). My other concern with the thickener is that I made up a base with water, ferulic, and ascorbic acid and tried several different thickeners. The one that contained the acrylamide copolymer broke down and turned the darkest by a large degree compared to the others.
  • PerryPerry Administrator, Professional Chemist
    Yes, small amounts of ingredients can cause significant colors.

    You could easily test this. Make a batch with only Ascorbic Acid and one with only Ferulic acid.  If there is no color, then you know the problem. 

    Although, it sounds like you already did a version of this by testing other thickeners. Since the other thickeners also changed color (albeit a lighter color) you know there is at least some reaction going on.
  • EVchemEVchem Member
    Yeah that's true. I guess I was hoping to find out what role the copolymer could play in exacerbating the oxidation
  • em88em88 Member
    Ascorbic acid is as well pH sensitive, beside temperature, light sensitive, oxygen and heavy metals.
    You can neutralize ascorbic acid with NaHCO3 to a pH 5-6.5 and if you add some EDTA in your formulation it will increase the stability more. 

    Ferulic acid is a similar case with ascorbic acid. 
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