Chemistry Reference
In-Depth Information
TABLE 4.22. Aggregation Numbers for Several Surfactants in Nonaqueous Solvents
Aggregation
T (
C)
Surfactant
Solvent
Number
n-C
9
COOCH
2
CHOHCH
2
OH
30
Benzene
41
n-C
9
COOCH
2
CHOHCH
2
OH
30
Cl benzene
16
n-C
11
COOCH
2
CHOHCH
2
OH
30
Benzene
73
n-C
11
COOCH
2
CHOHCH
2
OH
30
Cl benzene
47
n-C
13
COOCH
2
CHOHCH
2
OH
30
Benzene
15
n-C
15
COOCH
2
CHOHCH
2
OH
30
Benzene
15
n-C
15
COOCH
2
CHOHCH
2
OH
30
Cl benzene
9
n-C
17
COOCH
2
CHOHCH
2
OH
30
Benzene
11
n-C
17
COOCH
2
CHOHCH
2
OH
30
Cl benzene
3-4
n-C
12
H
25
(OCH
2
CH
2
)
4
OH
25
Benzene
40-50
n-C
13
H
27
O(CH
2
CH
2
)
6
OH
25
Benzene
70-80
Lecithin
25
Benzene
73
Lecithin
40
Benzene
55
Li
þ
Phenyl stearate
25
Benzene
20
Na
þ
Phenyl stearate
25
Benzene
25
K
þ
Phenyl stearate
25
Benzene
22
n-C
12
H
25
NH
3
þ
C
2
H
5
COO
25
Benzene
2
n-C
12
H
25
NH
3
þ
C
3
H
7
COO
25
Benzene
6
n-C
12
H
25
NH
3
þ
C
3
H
7
COO
25
Cyclohexane
3
n-C
12
H
25
NH
3
þ
C
3
H
7
COO
25
CCl
4
10
Na
þ
di-2-ethylhexylsulfosuccinate
30
Dodecane
32
Na
þ
di-2-ethylhexylsulfosuccinate
30
Cyclohexane
32
Na
þ
di-2-ethylhexylsulfosuccinate
30
Benzene
32
(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
Na
þ
dinonylnaphthalenesulfonate
25
Benzene
10
Li
þ
dinonylnaphthalenesulfonate
25
Cyclohexane
8
tion physical properties that are measured to determine micelle formation often
undergo a smooth, continuous transition over several orders of magnitude in con-
centration. As a result, the designation of a given concentration as the cmc may
become more a matter of the judgment of the investigator than the sensitivity of
the technique. The same potential problems are present in aqueous systems, of
course, but experience has shown them to be of only minor significance when
due care is taken in the experiments.
PROBLEMS
4.1. Estimate the size of spherical micelles that would be formed by a series of
single-chain hydrocarbon surfactants with chains of 10, 12, 14, 16, and 18
carbons.
