Comparatively Speaking: Alkyl Betaines vs. Amido Betaines

Jul 6, 2011 | Contact Author | By: Anthony J. O'Lenick Jr., Siltech LLC; and Robert J. Coots, PhD, Colonial Chemical Inc.
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Title: Comparatively Speaking: Alkyl Betaines vs. Amido Betaines
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Cocamidopropyl betaine (CAPB) is an important surfactant used in personal care. However, it is only one of a series of possible alkyl groups that can be used to make betaines. There are two types of betaines: alkyl betaines and amido betaines.

Amido betaine products are mild, foaming amphoteric surfactants that complex with anionics. They are used extensively in shampoos, bubble baths and in other cleansing products. The structure of alkylamidopropyl betaine is show in Figure 1.

Amido betaines can be derived from a variety of natural oils or fatty acids, the choice of which can profoundly effect the performance in formulations.

The selection of the specific material used in formulations will affect foam, skin feel and viscosity of the product. Cetyl betaine is derived from cetyl dimethyl amine and is an alkyl betaine.

The betaines selected for a formulation can alter viscosity, foam and feel of formulated products and is a major way that a formulator may affect product performance. A selection of betaines and their properties is shown in Table 1.

The foam and viscosity of the different betaines were evaluated in a simple formulation of 60.5% w/w water (aqua), 32% w/w sodium lauryl sulfate and 7.5% w/w betaine. The results are described in the foam properties of Table 1 and illustrated in Figure 2.

 

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Table 1. Source and foam properties of betaines

INCI Name Designation Derived From Foam Properties
Cocamidopropyl Betaine  COAB Coconut oil Highest overall foam height but the least stable, quickest flash foam
Lauramidopropyl Betaine  LMAB Lauric Myristic Fatty Acid   Densest foam, but less voluminous than COAB, requires more agitation
Cetyl Betaine  CET Cetyl dimethyl amine Second to LMB in density of foam, but has the longest sustained foam COB
Cocamidopropyl Betaine (and) Oleamidopropyl Betaine   COB Coconut Oil /Oleic Acid  Moderate foaming in comparison to others, good flash foam with open structure
Ricinoleamidopropyl Betaine   ROAB Castor Oil Moderate foamer with creamy after feel
Dimer Dilinoleamidopropyl Betaine  DLB Dimer Acid Moderate foamer with sustained foam and good after feel

Figure 1. Alkylamidopropyl betaine

Alkylamidopropyl betaine

The structure of alkylamidopropyl betaine is show in Figure 1.

Figure 2. Foam of betaines

The foam properties of betaines

The betaines selected for a formulation can alter viscosity, foam and feel of the finished product and is a major way that formulator may get different product performance.

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