For all compounds, hexagonal (H1), cubic (V1) and lamellar
(La) lyotropic mesophases were observed in water at certain
concentration intervals in the temperature range from 25 to
100 °C using the contact preparation technique. Lyotropic phase
behaviour sets in at concentrations above 36 (x = 0) to 66 wt%
(x = 5). The hexagonal phase is stable in the whole temperature
range for all surfactants except for x = 0, where it disappears
above 50 °C. The bicontinuous cubic phase is formed for
12-EOx-12 with x = 2–4 between 25 and 100 °C, for x = 0 only
above 35 °C, and for x = 1, 4 above 50 °C. For x = 0, the
lamellar phase occurs above 65 °C, for x = 1 above 50 °C and
for x = 2 above 40 °C. For x = 4 it is stable during the whole
temperature range and for x = 3, 5, only until the transition to
the isotropic melt occurs (see Table 1).
In summary, the mesophase behaviour of the 12-EOx-12
compounds is rather complex. Compared to geminis with short
and hydrophobic spacer units, the 12-EOx-12 compounds with x
! 2 form thermotropic liquid crystalline phases quite readily,
which can be easily identified. Therefore, such compounds may
be useful as solvents for chemical reactions or as templating
agents in the synthesis of inorganic materials. The lyotropic
mesophase behaviour of the surfactants is also of considerable
interest, since gemini surfactants with a hydrophobic spacer
chain have been found to form ternary polymerizable micro-
emulsions with styrene in water.8 Gemini surfactants with
hydrophilic oligo(oxyethylene) spacer are expected to exhibit
similar or even improved properties due to a higher flex-
ibility.
Fig. 2 Polarizing micrographs of the fan-like texture of 12-EO2-12 at 120 °C
(a) and of the mosaic textures at 180 °C (b)
Financial support by the Deutsche Forschungsgemeinschaft
(project Ti219/5-1) is gratefully acknowledged.
12-EO2-12
Notes and References
† Michael.Dreja@uni-koeln.de
‡ Tieke@uni-koeln.de
180 °C
§ Selected data for 12-EO2-12: C34H74N2O2Br2 (702.28) (Calc. C, 58.11; H,
10.61; N, 3.99. Found C, 57.97; H, 10.75; N, 4.13); dH(300 MHz, CDCl3)
0.85 (t, 6 H), 1.22, 1.32 (s, m 36 H), 1.7 (m, 4 H), 3.40 (s, 12 H), 3.54 (m,
4 H), 3.75 (s, 4 H), 3.90 (m, 4 H), 4.10 (m, 4 H); 12-EO3-12:
C36H78N2O3Br2 (746.84) (Calc. C, 57.90; H, 10.53; N, 3.75. Found C,
57.48; H, 10.54; N, 3.76); dH(300 MHz, CDCl3) 0.85 (t, 6 H), 1.22, 1.32 (s,
m 36 H), 1.70 (m, 4 H), 3.41 (s, 12 H), 3.54 (m, 4 H), 3.61 (m, 4 H), 3.72
(m, 4 H), 3.90 (m, 4 H), 4.08 (m, 4 H). 12-EO4-12: C38H82N2O4Br2 (790.89)
(Calc. 57.71; H, 10.45; N, 3.54. Found C, 57.81; H, 10.60; N, 3.67); dH(300
MHz, CDCl3) 0.85 (t, 6 H), 1.22, 1.32 (s, m 36 H), 1.70 (m, 4 H), 3.42 (s,
12 H), 3.6 (m, 12 H), 3.72 (m, 4 H), 3.88 (m, 4 H), 4.08 (m, 4 H). 12-EO5-12:
C40H86N2O5Br2 (834.94) (Calc. C, 57.54; H, 10.40; N, 3.36. Found C,
57.37; H, 10.59; N, 3.44) dH(300 MHz, CDCl3) 0.85 (t, 6 H), 1.22, 1.32 (s,
m 36 H), 1.70 (m, 4 H), 3.42 (s 12 H), 3.6 (m, 16 H), 3.72 (m, 4 H), 3.88 (m,
4 H), 4.08 (m, 4 H).
120 °C
25 °C
5
10
15
2q / °
20
25
30
Fig. 3 XRD spectra of 12-EO2-12 at 25, 120 and 180 °C
1 C. Tschierske, Progr. Polym. Sci., 1996, 21, 775.
2 C. A. Bunton, C. Robinson, J. Schaak and M. F. Stam, J. Org. Chem.,
1971, 34, 780; F. Devinsky, I. Lacko and T. Imam, J. Colloid Interface
Sci., 1991, 143, 336; R. Zana, M. Benrraou and R. Rueff, Langmuir,
1991, 7, 1072.
3 (a) F. Devinsky, I. Lacko, F. Bitterova and L. Tomeckova, J. Colloid
Interface Sci., 1986, 114, 314; (b) M. Diz, A. Mamresa, A. Pinazo, P. Erra
and M. R. Infante, J. Chem. Soc., Perkins Trans. 2, 1994, 1871; (c)
M. Pavlikova, I. Lucko, F. Devinsky and D. Mlgnarcik, Collect. Czech.
Chem. Commun., 1995, 60, 1213; (d) L. D. Song and M. J. Rosen,
Langmuir, 1996, 12, 1149.
4 A. Lu¨ttringhaus, F. Cramer, H. Prinzbach and F. M. Henglein, Liebigs.
Ann. Chem., 1958, 613, 185.
5 (a) S. Fuller, N. N. Shinde, G. J. T. Tiddy, G. S. Attard and O. Howell,
Langmuir, 1996, 12, 1117; (b) E. Alami, H. Levy, R. Zana and
A. Skoulios, Langmuir, 1993, 9, 940.
phase of 12-EO2-12 has a layered structure with a period of 24.8
Å. The splitting of the low angle peak may indicate the presence
of two coexisting crystalline modifications. At 120 °C, the
typical diffraction pattern of an Lb phase is apparent,6 indicating
that the alkyl chains attain a hexagonal packing with fully
extended chain conformation. The layer period is increased to
26.7 Å. At 180 °C, 12-EO2-12 adopts a smectic A structure6
indicating a disordered, liquid-like conformation of the alkyl
chains and a layer period of 28.6 Å. Compared with a fully
extended molecule (45.4 Å) or two extended C12 chains (33.4
Å), the repeat distance is much smaller. Therefore, we assume
an interpenetrating bilayer structure, as similarly proposed for
conventional gemini surfactants5 and U-shaped benzimidazo-
lium salts reported recently.7 For the La-phase of 12-EO3-12, a
period of 29 Å was found, while 12-EO4-12 has a layer spacing
of 25.2 Å in the viscous neat phase. Both values are very similar
to that of 12-EO2-12 and indicate the same structural arrange-
ments in the mesophases.
6 D. Tsiourvas, C. M. Paleos and A. Skoulios, Macromolecules, 1997, 30,
7191.
7 K. M. Lee, C. K. Lee and I. J. B. Lin, Chem. Commun., 1997, 899.
8 M. Dreja and B. Tieke, Langmuir, 1998, 14, 800.
Received in Bath, UK, 10th February 1998; 8/01448E
1372
Chem. Commun., 1998