Betaine Alternatives, Foaming Properties
While searching for betaine alternatives, I came up with sodium cocoamphoacetate and disodium cocoamphodiacetate as possible candidates. Based on my (albeit limited) understanding, betaines are often used in shampoo and body wash for the following benefits:
- Improved mildness
- Improved foaming
- Improved viscosity
As I am still learning about the different properties of surfactants, I decided to do a blender test on all of the ones that I own. I have heard that amphoterics are better at foaming than non-ionics, but less than anionics. This was confirmed in my blender testing. What surprised me, however, was that--at least for sodium cocoamphoacetate and disodium cocoamphodiacetate--this was only true at highly alkaline pH. When I performed blender tests at acidic (<6) and neutral (7) pH, the amphoterics produced less foam than non-ionics. I know that the charge of an amphoteric changes based on pH, but what I didn't know was how that affected foaming characteristics.
Anyway, here are my questions:
- Does cocamidopropyl betaine perform any better at the acidic pH that we would normally aim for when formulating shampoo?
- Similarly, is there a better alternative to the betaines that serves the same purpose?
- Is there some synergy that I'm missing, whereby betaines or amphoterics foam poorly on their own (in acidic conditions), but somehow still manage to boot foaming of other surfactants?
- Exactly how do these surfactants thicken? I see that claim for all three in my post, but I'm not sure how it works. Do they adjust the salt curve or is there something else?
Sorry for so many questions; I'm still learning