I’ve been researching surfactants – here are my notes.
My job is varied and interesting but it also does my head in. Why? Because everything is interesting, everything is an opportunity to learn more, be better, run faster, jump higher and solve world hunger (well, no it isn’t really but anyway) and that can become totally overwhelming. Anyway……….
It just so happens that I’ve found myself in a surfactant bubble for the last four months after having been invited to formulate quite a few products for quite a few different companies (8 in fact which is a nice neat number). Anyway, not one to churn out the same old-same old day after day I’ve been playing and found a few rather fabulous combinations to tickle the taste buds and lick the dirt off even the most crusty of customers (and before you get excited that’s salt on the scales there. Table salt).
But I can’t tell you about all of that here because it’s top secret so instead I thought I’d share some basic overview notes with you about how surfactants work as believe it or not, there’s some science involved. No, really I’m serious about this science stuff………….
My notes on surfactant chemistry.
Too hard to read? Try this:
Anionic Surfactants form charged micelles that act like little magnets picking up dirt. They pull the dirt from a surface and it is emulsified away from the surface. This is more of a physical reaction in-situ than a chemical one as the dirt isn’t changing form on the skin as such – it is emulsified in the rinse.
They can form sphere, rod or disk-shaped micelles and it is the spheres that form the thickest mixtures.
They work best just above their CMC (Critical micelle concentration) as this is when the surface activity is highest = largest surface area.
Bigger aggregates can form and these are otherwise known as liquid crystals (emulsifiers form these sometimes)
Salt decreases the surfactant CMC which means that less irritating and more effective formulations can be created for a lower cost. They are also more efficient for the environment as less material needs to be used. Salt works best with anionics.
Anionic and Cationic surfactants generally have higher CMC’s than non-ionics due to the interactions between the head groups. However, this can be dramatically reduced with the addition of amphoterics.
Glucosides are non-ionic and tend to remove dirt by emulsifying it. This is a chemical reaction that occurs at the site of the dirt. You rinse off the emulsified oil.
Glucosides have lower HLB’s as the chain length reduces so C8 has a high CMC (Caprylic) at 18 whereas C10 has only 1.8 (capric). C12 has a CMC of 0.18.
Decyl and Cocoyl glucoside have the same range of chain lengths C8-C16 which is also known as a broad cut.
Zwiteronic surfactants such as cocamidopropyl betaine have smaller CMC’s than anionics.
Most but not all modern surfactant systems combine mixtures of all three types of surfactant to give highly effective cleaning solutions. There are some useful synergies between different surfactant groups but some are good enough to use alone. Depends on what you want really.
Getting my hands ‘dirty’ or thoroughly degreased (I only use mild surfactants but they are still potent – the dose makes the poison my dears).
I’ve been playing with surfactants for a good 13 years now after being lucky enough to work alongside some of Akzo Nobel’s greatest back in the 90’s. These years have been pretty interesting as the push to greener and more sustainable surfactants picked up its pace. When I joined the industry cleaning companies were still relying on nonyl phenol ethoxylates and harsh (and I mean harsh) solvents to clean our hard surfaces whereas nowadays most are using much more degradable and less polluting ingredients. The cosmetics industry has also seen an evolution and although many of the multinationals are sticking with their SLES/ Betaine type shampoos and bubble baths (because they work, are cost-effective, relatively mild and are actually ‘greener’ than ever due to efficiencies in processing etc) more and more brands are playing with some newer stuff such as lactylates, glucosides, amino-acid derived surfactants and natural saponins.
The point of showing you this is two fold. A) Because there is some really interesting science behind why I do what I do and I do think that it is important to share that and most importantly B) Because I want to encourage you, the product maker, the interested reader, the health provider, the hobbyist or the environmentalist to discuss the ingredients that we use in cosmetics in an intelligent and thoughtful way so that we can come up with bigger, better, faster, stronger, world-hunger curing solutions together.
That sound OK? Great, let’s get cooking!