Skip to content

Experimenting with different emulsifiers

September 21, 2016

I know there are lots of different types of emulsifiers but how do different emulsifiers make my emulsion feel?

After all the reading in my last article: The Secret Life Of The Emulsifier  I feel it is time to bring things back to the lab again as we try out a very simple yet effective experiment to demonstrate how one might answer that very important question ‘This chemistry is all well and good but how do these emulsifiers FEEL?’

I developed a very simple formula based on a common non-ionic emulsifier – Cetearyl Alcohol and Cetearyl Glucoside. This formula was then replicated with different emulsifiers, one from each different class (except silicone). The products were evaluated by an expert panel of five people as well as having their viscosity checked before being evaluated under the microscope. The idea of this base formula was for it to be stable and easy, I wasn’t too bothered about anything else at that stage.

The formula and feedback is not presented to help sway a decision towards or away from a particular type of emulsifier, merely it is to illustrate a point, that the emulsifier can impact everything from viscosity to feel, efficacy to stability. It also demonstrates the importance of optimizing the whole formula so as to get the most out of the emulsifier of choice. Plus there is always room for pairing up on technologies or trying something new!

So the only difference between these formulations is the emulsifier except for the cationic version which was incompatible with the thickener Acacia and Xanthan gum blend. In the cationic I used a cationic guar at the same level.

 

Formula 1: Cationic (Brassicyl Isoleucinate Esylate (and) Brassica Glycerides (and) Brassica Alcohol)

 

Formula 2: Anionic (Potassium Cetyl Phosphate)

 

Formula 3: Non-Ionic (Cetearyl Alcohol, Cetearyl Glucoside

 

Formula 4: Mixed Anionic/ NonIonic. (Glyceryl Stearate (and) Cetearyl Alcohol (and) Sodium Stearoyl Lactylate)

 

Formula 5: Non-Ionic Synthetic (Cetearyl Alcohol, Ceteareth-20)

 

Formula 6: Polymeric (Acrylates/C10-30 Alkyl Acrylate Crosspolymer)

Formula 7: Liquid Crystal Emulsifier (Cetearyl Olivate, Sorbitan Olivate).

Formula 8: HLB balance (Sorbitan Monooleate, PET-20 Sorbitan Monostearate)

Formula Number

Skin Feel

Viscosity @ 3.0 Spindle

1

Thin, high spreading, slightly tacky to touch at first drying to powdery.

19,380

2

Silky, takes a while to absorb, feels substantive after drying.

90,630

3

Easy to rub in

56,250

4

Easily absorbed

74,690

5

Very thick and creamy, light after feel

160,600

6

Ultra-light, quick break and high spreading. Tacky on drying.

15,310

7

Rich waxy texture, slow spreading

82,190

8

Very light and spreadable

13,440

 

Base formulation used.

 

Phase Ingredient % 200g Function
A. Water Phase Deionised Water 71.95 143.9 Solvent
  Acacia and Xanthan Gum 0.4 0.8 Thickener/ Stabiliser
  Glycerin 3 6 Humectant
  EDTA 0.1 0.2 Chelating Agent
 
B. Oil Phase Jojoba Oil 8 16 Emollient
  Shea Butter 8 16 Barrier Protection
  Squalane 2.5 5 Emollient
  Emulsifier of choice 3 6 Emulsifier
  Cetearyl Alcohol 1.25 2.5 Emulsion Stabiliser
C. Finishing Touches Natural Vitamin E 0.5 1 Antioxidant
  Perfume 0.3 0.6 Aroma
  Preservative (Phenoxyethanol, Ethylhexylglycerin) 1 2 Broad Spectrum Preservative
TOTAL   100 200  

 

 

Microscope Slides:

As expected the polymeric emulsifier produced the largest dispersed phase droplets.

Top: Formula 6: Polymeric (Acrylates/C10-30 Alkyl Acrylate Crosspolymer) 

Bottom: Formula 5: Non-Ionic Synthetic (Cetearyl Alcohol, Ceteareth-20)
microscope-slides-polymeric-and-nonionic

nonionic

The Cationic emulsifier Vs Anionic Emulsifier.

cationic

cationic-and-anionic-slides

Stability:

4 weeks in 40C oven pass at time of going to press.

Conclusion.

There really is a lot to take in when developing complex cosmetic formulations including the ionic strength and polarity of your water phase, your marketing departments wishes, the viscosity and feel you are trying to achieve and the packaging you hope to sell in. That said, today we are lucky enough to have at our finger tips a wide range of different ‘drop-in-and-go’ technology to help us balance creativity with tight deadlines. My only hope is that we remain engaged and inspired by the chemistry that underpins this convenience so we can keep on innovating for centuries to come.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: