CMC Values

Quick Start

Because I think that CMC values are over-rated (who's interested in the behaviour of pure surfactants in pure water?), I felt no need to provide a list of CMC values. But people said that such a list would be useful, so here it is.

My colleague Dr Hiroshi Yamamoto shows on his Pirika cmc pages how it is possible to correlate cmc values with surfactant structure along homologous series.

Surfactant Science Critical Micelle Concentration CMCAs a reminder, the Critical Micelle Concentration is the concentration at which the surfactant molecules start to assemble into clusters as shown in this image from Hiroshi's site.

Hiroshi kindly gave me the dataset he had assembled from various sources and I've added a few values of general interest. Given that many of these values are for scientifically pure surfactants and that most of us use industrial grade surfactants, the numbers should be treated as illustrative only. In addition the values depend on temperature and salinity which for this table can be assumed to be 25° and "low" respectively.

Broadly speaking the data show that for ionics the head group doesn't make a big difference and that the cmc decreases steadily (in a log fashion) for longer chain lengths and that cmc is simply estimated via molar volume. Ethoxylates follow a similar trend but the EO head is not very hydrophilic so the cmc for a given alkyl chain is much lower. Hiroshi's site explains all this in detail, and also shows that fluorosurfactants (not included in this table) follow the same trend - it is molar volume (and the F atoms are much bigger so cmc is much smaller) not molecular weight that is important.

Surfactant cmc mM Surfactant cmc mM Surfactant cmc mM
CO2Na Carboxylates -NH3Cl Amm. Cl C12E8 0.109
C7 390 C10 54 C13E8 0.027
C8 210 C12 14.7 C14E8 0.009
C9 100 C14 2.8 C15E8 0.0035
C10 50 C16 1.1 C16E8 0.0025
C11 24 C18 0.25 C10E9 1.3
C12 12 -NMe3Br TMA Br C12E9 0.1
C13 7 C8 290 C16E9 0.0021
C15 2 C9 139 C12E12 0.14
C17 0.5 C10 60 C16E12 0.0023
Oleic 1 C11 36 C8PhE1 0.0495
OSO3Na Sulfates C12 13.3 C8PhE2 0.0765
C7 240 C14 3.41 C8PhE3 0.103
C8 130 C16 1 C8PhE4 0.13
C9 65 C18 0.29 C8PhE5 0.15
C10 33 -PyBr Pyr. Br C8PhE6 0.21
C11 16 C8 193 C8PhE7 0.25
C12 8 C10 85 C8PhE8 0.28
C13 4 C11 42 C8PhE9 0.3
C14 2.2 C12 11.4 C9PhE9 0.11
C15 1.2 C14 2.9 C9PhE15 0.12
C16 0.58 C16 0.6 C9PhE20 0.16
C17 0.3 Ethoxylates Others
C18 0.23 C8E1 4.9 DHSS 1.75
SO3Na Sulfonates C8E3 7.5 Tween20 0.06
C8 155 C10E3 0.6 Tween40 0.03
C10 41 C7E4 40 Tween80 0.01
C12 11 C8E4 11.7 C8Gly1.5 84
C13 3.5 C10E4 0.68 C10Gly1.5 2
C14 2 C8E5 11 C12Gly1.5 0.15
C15 0.66 C10E5 0.81 C16Gly1.5 0.0006
C16 0.54 C12E5 0.064 Sophorolipids 0.15
C17 0.21 C8E6 9.9 Rhamnolipids 0.1
C18 0.19 C10E6 0.9
C6Ph 37 C12E6 0.087
C7Ph 21 C14E6 0.01
C8Ph 14 C12E7 0.08
C9Ph 6.5 C16E7 0.0017
C10Ph 3.1 C8E8 9.7
C12Ph 1.2 C10E8 1
C14Ph 0.66 C11E8 0.3