Thickening Surfactant Based Products

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Salt
Salt thickens by reducing micelle charge density, helping to promote the conversion of spherical micelles to rod-shaped micelles.

The viscosity of surfactant solutions is normally dependent on the size of the surfactant micelles, concentration of surfactants, the type/ratio of the surfactant used, temperature, and the micelle charge density.

Most thickeners work by promoting the formation of rod-like micelles by reducing charge density or crosslinking micelles. The optimum choice depends on the specific needs of the formulation, which include clarity, PH, ingredients to suspend, and the types of surfactants/concentration used. Other considerations include cold processing, and natural or PEG-free claims.

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An efficient system will normally use <2% thickener to achieve a functional viscosity of 5-10K cps using a typical 12.5% alkyl sulfate/2.5% Cocamidopropyl Betaine surfactant system. When designing a thickening system, try to use multifunctional ingredients that can provide additional benefits to the formulation, and use combinations of ingredients that work by different mechanisms to improve efficiency. Potential benefits of different classes of thickeners include:

  • Liquid, cold processing with minimal mixing.
  • Good low and high temperature viscosity and stability.
  • Good fragrance solubilization.
  • Synergy with salt.
  • Good formulation clarity.
  • Help to increase foam/lather.
  • Improved mildness.
  • Suspend and stabilize particles.

Thickening Technologies for Surfactant Based Products

Salt

Salt thickens by reducing micelle charge density, helping to promote the conversion of spherical micelles to rod-shaped micelles. Historically, sodium chloride has been used. However, divalent salts like magnesium sulfate are more efficient if compatible in the formulation. Viscosity of salt-thickened formulations decreases with increasing temperature and will not stabilize suspended particles. Using too much salt (>2%) can also impact the clarity and cloud point of the formulation.

Polymers

Polymers are typically aqueous acrylate dispersions that work by crosslinking micelles. Cellulosic ethers are also used.

Aqueous acrylate polymer dispersions are preferred due to their ease of use and synergy when combined with salt. They are also excellent at suspending particles in formulations. Some examples of polymeric thickeners include:

  • Carbopol Aqua SF-2 (Acrylates Crosspolymer 4, 32% solids) by Lubrizol
  • Rheomer 33 (Polyacrylate 33, 29% latex solids) by Solvay Novecare
  • Eliclear 4U (Acrylates Copolymer) by Seppic
  • Methocel 40-101 (Hydroxypropyl Methylcellulose) by Dow Chemical

Polar Emollients/Low HLB Surfactants

Ingredients with a low HLB value like Laureth-3, Cocamide MEA and other polar lipids work by promoting the formation of rod-like micelles. These micelles are flexible, branched structures, which may entangle and dramatically increase viscosity.

Examples of polar emollients/low HLB surfactants include:

Nonionic Ethoxylated Surfactants

Nonionic ethoxylated surfactants work by cross linking micelles. Surfactants with more than 1 hydrophobic tail are more efficient and can attach to multiple micelles, leading to an increase of viscosity.

Some examples of nonionic ethoxylated surfactants include:

  • Ethox NEBS-2 (Decyltetradeceth-200 Behenate) by Ethox
  • Genapol LT (PEG-150 Polyglyceryl-2 Tristearate, Laureth-3, Dipropylene Glycol) by Clariant
  • Dermothix 100 (Disteareth 100 IPDI) by Alzo

Amphoteric Surfactants

Sometimes referred to as secondary surfactants, amphoteric surfactants promote the formation of rod-like micelles by reducing micelle charge density/repulsion. They also significantly improve mildness, boost foam/lather, and synergistically work with salts to build viscosity.

Some examples of amphoteric surfactants include:

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21 Responses to “Thickening Surfactant Based Products”

  2. For example I have bought crothix in liquid for and in pebble form. I would love to be able to make a thickener in advance so I can add it to my formula.
    Any suggestions or help in this matter?
    thanks for your time,
    Greg

  3. Pleas what ratio Can I use to formulate Sodium stearate between Stearic acid and Sodium hydroxide in production of Stick Deodorant

  4. Hello
    I use the hydroxy ethyl cellulose(HEC) in the formulations as a viscosity.
    I have some difficulties to dissolve the product in the mix and especially industrially.
    Thanks for your help.
    Best regards
    TAYCIR BAHLOUL
    Head laboratory and R & D control

  5. Pre-wet the material by dispersing it in a glycol prior to addition to the aqueous phase. This prevents agglomeration and drastically reduces time to full dispersion.

  6. I am trying to thicken sulfate free surfactant systems. For example 50% of a decyl Glucoside (as supplied) and 50% water. What will be a good thickener for this?

  8. I have achieved satisfactory thickening and lather using 8% surfactant combo, .5% HPMC and 1% sodium chloride but formulation is quite cloudy. You have any idea how to correct this? Thanks already

  10. Thanks for the article, I found the information about divalent salts / magnesium sulphate as thickener very interesting, what surfactants are compatible / will thicken with divalent salts / magnesium sulphate?

  11. Dear sir,

    Any body can give me recipe how i can thicken sodium chlorite?
    Viscosity 8000 -10000 cps.

  12. Please sir , what is the ratio of magnesium sulphate and sodium chloride In lasba base liquid detergent.

  16. I am formulating a two phase system of surfactant and oil.
    How do I thicken the surfactant phase so that after mixing the product I can obtain two separate layers quickly.
    I have used NaCl but it takes 24 hours to separate.

    Kindly Help.

  17. Very difficult to have rapid phase separation when you have high concentrations of surfactants. Increasing the water phase density using polyols and salt will help. Also use an oil phase that has the lowest possible density with the lowest possible surfactant concentration.

  18. I have tried NaCl to thickening a 15%SLES & 85%Water solution but not succeeded. What min. quantity of SLES should be added to water for thickening with NaCl.

  19. You need to include Cocamidopropyl betaine in the formulation. It will also help stabilize the foam and make the formulation milder.

  20. Hello,

    we’re in need of a thickening agent to thicken dewatered food processing waste water so it can be hauled safely. Preferably one that we could leave in the bottom of a container while the waste water sludge is deposited.

    Can you or one of you colleagues reach out to me?

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