Self-Assembly in Lipidic Particles - Self-Assembled Supramolecular Architectures: Lyotropic Liquid Crystals - page 132

94°C
87°C

ELPs

1

77°C

68°C
58°C

Hexosomes

49°C

39°C
30°C

Cubosomes

20°C

0 1 2 3

q [nm -1 ]

Figure 5.3 Temperature dependence of the SAXS curves for the same MLO-based
dispersion described in Figure 5.2. [Reprinted from de Campo et al. (2004).]

three temperatures: 25, 60, and 98°C. Increasing the temperature [as discussed
in de Campo et al. (2004) and Yaghmur et al. (2005)] was expected to induce
a dehydration of the MLO headgroup. This would lead to an increase in the
kink states in the lipid acyl chains and thereby their effective volume would
also increase. As a consequence, the negative spontaneous curvature would
become enhanced.
Our results clearly indicated a remarkable resemblance in the SAXS pat-
terns; the peak positions for the bulk and the dispersion were identical. The
confi ned nanostructure was preserved in all investigated temperatures. Owing
to this identical nanostructure in both the dispersed and nondispersed phases,
the water content in the dispersed droplets could be readily calculated from
the maximum water solubilization capacity of the fully hydrated nondispersed
systems (their structures were independent of the water content) (de Campo
et al., 2004; Yaghmur et al., 2005). An additional interesting point is the signifi -
cant decrease in water solubilization capacity with increasing temperature.
For instance, the internal nanostructure of the cubosome particles contained
33 wt % water at 20°C, whereas the ELP contained only 20 wt % water at
94°C, in analogy with the nanostructure of the corresponding nondispersed
bulk phase (as shown in Fig. 5.1).
As mentioned above, the symmetries of the internal phase were preserved
for all investigated temperatures. Only our results revealed that the internal