Sunday, April 11, 2010

Surfactants: Alkyl sulfonates

There are three main types of alkyl sulfonates - primary paraffin sulfates (PPS), secondary paraffin sulfates (SPS) or secondary alkyl sulfates (SAS), and alpha-olefin sulfates (AOS).

The paraffin sulfonates are good foamers and good oil in water emulsifiers. They do not thicken with the addition of salt. I can't find any examples of these surfactants.

The alkane sulfonates, however, are all around us. I use them as Bioterge AS-40 (liquid) or Bioterge AS-90 (powder) and the INCI is Sodium C14-16 Olefin Sulfonate. (Click here for the version from the Personal Formulator.)

You can find this in Bioterge 804, which I've used a lot in the past, but since Voyageur is no longer carrying and I can't find it elsewhere, I haven't written much about it here. Click on the link to see the data bulletin sheet.

These are mainly used in detergents and syndet bars, as well as shampoos, bubble baths, and body washes. They have great flash foam and good cleansing. They are less irritating than the alkyl-aryl sulfonates (more on those tomorrow). The ideal length is C14 with C13 to C18 preferred for cosmetic formulating.

If you are using an alkane sulfonate in home cleaning products, remember they are unstable when you add bleach thanks to that OH group on the last group! Because they are less sensitive to hard water than a lot of the surfactants and because they are readily biodegradable, alkane sulfonates are used in some home cleaning products!

In the form of Bioterge AS-40, the pH is around 8.5 (slightly alkaline) and it is 39% active. It can cause moderate skin and eye irritation at around 10% active ingredients (25% in your formulations). In the form of Bioterge AS-90 (powder), the pH is around 10 (quite alkaline) and is 88% active. At 1% active (so a little less than 2% in your formulation) it can cause mild to moderate skin and eye irritation.

The alkyl sulfonates are fantastic cleansers for oily to very oily hair and skin. They can be made much less irritating by including an anti-irritant like Crothix or glycol distearate (EZ Pearl) or by combining surfactants. I like a combination of BSB, Amphosol CG (cocamidopropyl betaine), and Bioterge AS-40 for body washes and shampoos. They are great additions to a bubble bath because they have great flash foam - the initial cascade of bubbles when you add it to the water. And they are great for hand washes because of that flash foam!

They are difficult to thicken, which is why I always use gel or Crothix when I include this surfactant.

Finally, they are great emulsifiers. So if you wish to include some oils in your surfactant mixture - essential or fragrance oils or a light oil like sunflower - you can do so up to about 2% to 3% without adding solubilizers like polysorbate 20 or polysorbate 80!

Here are a few formulating ideas for alkyl sulfonates!

Do not consider using Bioterge AS-90 (powder) in the place of SCI in a shampoo bar. I've tried it many times when I couldn't get SCI in Canada, and it is far too soft and a little too degreasing for my hair! You can use it in place of SLSa if you wish!

If you wanted to make a bubble bath powder, AS-90 is a great choice, combined with SLSa!

Click here for the data bulletin for Bioterge AS-40 (liquid) or Biotgerge AS-90 (powder).

Join me tomorrow for fun with alkyl-aryl sulfonates!


Anonymous said...

Is Sodium C14-17 secondary alkyl sulfonates considered a quaternary ammonium?

Susan Barclay-Nichols said...

No. It doesn't contain an ammonium ion and it isn't positively charged.

sagar said...

Hi Susan,

I have some issues with Alpha olefin sulfonate based surfactant. It is 70% active (30% water) but it is very viscous product. It is flowable around 80 deg C only we have problem during tanker unloading. How can I reduce the viscosity of this product without affecting application part. Thanks for your reply in advance.

Susan Barclay-Nichols said...

Hi Sagar. I'm afraid I don't know anything about industrial applications of surfactants, so I can't offer any help.