Crodamol STS (aka PPG-3 benzyl ether myristate, but I'm typing Crodamol STS instead!) is a PPG-ester that behaves a lot like our alkyl esters! It's a great detackifier, good spreader, and dry feeling emollient. It offers good film forming abilities on our hair and skin, which is why it's considered a silicone substitute for dimethicone.
It can be used at 1% to 15% in our products, but it disperses well in surfactant systems (like shampoo or body wash) at 3%. It is soluble in alcohol, insoluble in water, and soluble in oils and cyclomethicone. It is soluble in some surfactants like ammonium lauryl sulfate (ALS) and triethanolamine lauryl sulfate (TEALS), and dispersible in sodium laureth sulfate (SLeS).
What's the difference between soluble and dispersible? When something is soluble, it means it will dissolve in the solvent and becomes part of a homogeneous solution. Think of it like salt dissolving in water. If you've dissolved it correctly, you can't see the flecks of salt floating in the water. When something is dispersible, it means it will stay suspended in the mixture, but it will always be separate and won't form a homogeneous solution. When we use fragrance or essential oils in something like a body wash, the oils aren't dissolved but suspended. We don't notice a huge difference unless those oils separate out and form an oily mass on top of the body wash, which can happen if you use too much!
Crodamol STS is used in a lot of mineral make-up products as a pigment wetter - apparently it's good for pressing powders - and in lipsticks because of its great wax solvency. It's considered a great inclusion in foundations because it has a non-greasy feel and great spreading abilities.
It's used in anti-perspirants to reduce tackiness and increase glide. It's a good emollient in body oils because of its great spreading, detackifying, and gliding properties. And it's good for bath oils as it spreads well on water. It's easily emulsifiable in any lotion products, and can be used as a substitute for any oils you might include in a lotion or cream.
Where Crodamol STS really shines - and you'll excuse the pun in a moment - is in hair care products. It's used as an alternative to dimethicone because it can offer film forming, emolliency, and detackifying like this silicone. (Note though, dimethicone is approved as a barrier ingredient by the FDA; Crodamol STS isn't.) It works as a skin and hair conditioner, increasing detangling and lubricity of our hair.
Remember that we want to reduce the friction on our hair, which will increase the ease with which we can comb our hair wet and dry, and it decreases damage as the hair strands can move more easily over other strands.
Where a lot of the silicone substitutes fail is in the shine that dimethicone normally gives to our hair. Crodamol STS offers higher refraction rates than cyclomethicone or dimethicone, which means it should make our hair look shinier.
An aside on the refractive index...All materials reflect and refract light, which is to say all materials alter the angle of light. The refractive index is a ratio defined as the speed of light in a vacuum (which equals 1) over the speed of light in the material. Light slows down when it enters a substance, so every refractive index will be over 1. The higher the refractive index, the higher the light intensity reflected from the surface. Titanium dioxide has a refractive index of 2.7, one of the highest of all materials, and diamonds are about 2.419 - and we know how sparkly they can be! - whereas water is around 1.33.
So based on the refractive index, Crodamol STS should make your hair appear shinier with a refractive index of 1.4696 versus cyclomethicone's 1.394 to 1.398 and dimethicone's 1.375 to 1.403. It should give you a better shine than either of the silicones, and can be used with the other silicones in your products!
Does it work as well as a dimethicone substitute in my oh-so-humble opinion? My hair rarely shines with all the kinks and curls, so I can't judge it on that basis. It works well as a dimethicone substitute for lubricity, emolliency, and conditioning in shampoos and conditioners, but I couldn't recommend it for a frizzy haired girl like me as it simply doesn't repel the water enough to keep the frizzies away in really humid conditions! I've tried it in conditioners, leave in conditioners, and anti-frizz sprays and although my hair felt really nice, the de-frizzing ability in my hair was on par with using cyclomethicone alone, which is to say it felt like I wasn't using any dimethicone at all!
This is just my opinion, though. Try it for yourself by creating a lovely shampoo tomorrow, then a conditioner with the Crodamol STS and see what you think!