Question: What is the meaning of positive or negative charge? Cationic, anionic, and non-ionic charges

In this post, How can we adapt our formulas to be more natural: Gelling agents, Catherin asked: What is the meaning of positive and negative charge?

I wrote about this topic in this post on the blog – Anionic, cationic, and non-ionic – but I realized I’ve learned so much since 2011 and there are so many more ingredients about which this is relevant, so let’s take a closer look at this topic!

Anionic, cationic, and non-ionic refer to the electrical charge on the ingredient in question.

Non-ionic means it has a neutral charge.
Anionic means it has a negative charge.
Cationic means it has a positive charge.

Our hair and skin are negatively charged or anionic. Positively charged or cationic ingredients will adsorb or form a fine layer on your hair or skin in a process called substantivity. This is how hair conditioners work, they form this film to make the cuticle lay flatter, which reduces tangling, increases shine, increases softeness, and reduces static.

Why should we care about the charge? We usually don’t want to mix something anionic with something cationic, as you’ll see, but we can mix either with non-ionic ingredients.

Polawax, emulsifying wax NF, Simulsol 165/Lotionpr™ 165, and Natragem EW are non-ionic or neutrally charged emulsifiers. We can add anionic things, like xanthan gum, Sepimax ZEN, and Sepinov EMT 10, to these lotions with it without problem. We can add cationic things, like honeyquat or polyquat 7, which are cationic polymers, without issue.

Incroquat BTMS-50, Incroquat BTMS-25, Rita BTMS-225, Varisoft EQ 65, stearamidopropyl dimethylamine, and other hair conditioning type emulsifiers are positively charged or cationic, so you don’t want to add those anionic ingredients, like xanthan gum, Sepimax ZEN, or Sepinov EMT 10 to this mix. You can add non-ionic ingredients without problem.

Ritamulse SCG, Sepimax ZEN, Sepinov EMT 10, and xanthan gum are anionic or negatively charged, so we can’t use cationic polymers with them. Some hydrolyzed proteins have a slightly positive charge, so with the gelling agents, we can’t use them lest we lose that lovely viscosity.

When it comes to bubbly, foamy, lathery surfactants, most of them are anionic or negatively charged, but there are a few exceptions.

Sodium lauryl sulfate, sodium laureth sulfate, sodium coco sulfate, sodium lauryl sulfoacetate, C14-16 olefin sulfonate, disodium laureth sulfosuccinate, sodium cocoyl isethionate, hydrolyzed silk surfactants, and more, are anionic or negatively charged ingredients. Soap is also negatively charged.

Decyl glucoside and lauryl glucoside are non-ionic, so they mix with almost anything. (Things like polysorbate 20, polysorbate 80, caprylyl/capryl glucoside, PEG-40 hydrogenated castor oil, and so on are also considered non-ionic surfactants.)

Cocamidopropyl betaine, cocamidopropyl hydroxysultaine, sodium lauroamphoacetate, sodium cocoamphoacetate, and babassuamidopropyl betaine are all zwitteronic or amphoteric, meaning they have different charges at different pH levels. Generally, in alkaline products or those with a pH over 8, they’ll be anionic or negatively charged. They all increase mildness of anionic surfactants and increase viscosity.

Related post: pH! 

In general, you can combine these surfactants together without a lot of concerns, although there may be some issues with thickening. Most of the blends you can buy, like BSB, Miracare Soft 313, Plantapon SF, are combinations of surfactants that generally include at least one anionic and one amphoteric surfactant.

One of the questions I’m asked all the time – and have realized after doing a search on the blog I haven’t answered – is how can we combine something like honeyquat or polyquaternium 7, which are positively charged, in shampoos or body washes, which will be negatively charged. The short answer is that these cationic polymers are designed to be used with these negatively charged blends. (The long answer will be posted shortly as it’s an interesting topic!)

Why do we care about any of this? There are a few reasons….

1. We don’t want to make products that fail, so knowing what goes with what can prevent separation, loss of viscosity,

2. We don’t want to inactivate our preservatives. Parabens can be deactivated by polysorbates, for instance, while Tinosan SDC won’t work with cationic ingredients.

3. We want to make sure we have products in the right pH range of their charge. For amphoteric surfactants, like cocamidopropyl betaine, if we want them to be positively charged to adsorb to hair and skin, we need to get the pH below 6. With some of these new conditioners with which I’m playing, we have to get the pH down to a certain point to ensure they’re cationic. Otherwise, they’re just another emulsifier.

Wow, what an interesting topic, eh? There’s so much more to share with you on this topic, but that will have to wait for another day!