Chemistry Reference
In-Depth Information
TABLE 4.21. Critical Micelle Concentrations for Some Surfactants in Organic Media
T (
C)
Surfactant
Solvent
cmc (mM)
Na
þ
di-2-ethylhexylsulfosuccinate
30
Cyclohexane
1.6
Na
þ
di-2-ethylhexylsulfosuccinate
30
Benzene
3
Na
þ
di-2-ethylhexylsulfosuccinate
30
Dodecane
3
Li
þ
dinonylnaphthalenesulfonate
25
Cyclohexane
1.1
Na
þ
dinonylnaphthalenesulfonate
25
Benzene
0.1
1
Ba
2
þ
dinonylnaphthalenesulfonate
25
Benzene
0.1
1
n-C
12
H
25
NH
3
þ
C
2
H
5
COO
25
Benzene
2.2
n-C
12
H
25
NH
3
þ
C
3
H
7
COO
25
Benzene
1.8
n-C
12
H
25
NH
3
þ
C
4
H
9
COO
25
Benzene
2.0
n-C
12
H
25
NH
3
þ
C
3
H
7
COO
25
Cyclohexane
2
n-C
12
H
25
NH
3
þ
C
3
H
7
COO
25
CCl
4
1.6
n-C
18
H
37
NH
3
þ
C
2
H
5
COO
25
Benzene
8
n-C
18
H
37
NH
3
þ
C
3
H
7
COO
25
Benzene
2.7
n-C
12
H
25
(OCH
2
CH
2
)
4
OH
—
Benzene
1.6
n-C
13
H
27
O(CH
2
CH
2
)
6
OH
—
Benzene
2.6
n-C
12
H
25
(OCH
2
CH
2
)
4
OH
—
Benzene
1.6
n-C
13
H
27
O(CH
2
CH
2
)
6
OH
—
Benzene
2.6
(n-C
7
COO
)
2
Zn
2
þ
—
Toluene
6
(n-C
9
COO
)
2
Zn
2
þ
—
Toluene
5
(n-C
11
COO
)
2
Zn
2
þ
—
Toluene
4
dinonylnaphthalene sulfonate in benzene was found to be essentially constant for a
series of 10 different counterions, indicating a lack of sensitivity to the nature of the
cation.
The effect of the hydrocarbon tail length in a homologous series of surfact-
ants was found to be relatively small when compared to that in water. It was
shown, however, that the aggregation numbers of the micelles decreased as the
carbon number increased for a series of quaternary ammonium halides and metal
carboxylates.
The presence of small amounts of water in a nonaqueous surfactant environment
can have a significant effect on some systems. Particularly large effects have been
found in solutions of sodium di-2-ethylhexylsulfosuccinate in toluene and phenyl-
stearate soaps in benzene. It can be presumed that the effects of water and other
impurities on nonaqueous micelle formation stem from alterations in the dipolar
interactions between head groups induced by the additive or impurity. Although
cmc values for a number of systems are listed in Table 4.21, the uncertainties asso-
ciated with the nature of the aggregation process and of the aggregated species
make a lengthy discussion of the type given for the aqueous systems complicated
and somewhat more speculative than aqueous systems. That is not to say, however,
that such phenomena are not theoretically and practically important. While the
micellization process occurs in water, with some exceptions, over a fairly limited
concentration range, the same is not always true for the nonaqueous process. Solu-
