Self-Assembled Liquid Particles: How to Modulate their Internal Structure - Food Colloids: Self-Assembly and Material Science - page 75

temperature in a reversible way. Upon increasing the temperature, the internal
structure undergoes a transition from cubic via hexagonal to fluid isotropic,
and vice versa, in analogy to the binary MLO samples in equilibrium with
excess water. This change in topology induces a different water intake in the
particles. The internal structure expels water with increasing temperature in a
reversible way. At each temperature, the internal structure of the dispersed
particles corresponds very well to the structure observed for nondispersed bulk
MLO with excess water. As this behaviour is independent of any thermal
history, these particles are considered to be in thermodynamic equilibrium with
the surrounding water phase.
5.3 Solubilization of Oils in Self-Assembled Structured
Particles
5.3.1 Emulsification of Microemulsions
Incorporation of oil is of special interest from both the scientific and the
industrial points of view. Indeed, one remaining question in the field is to know
whether it would be possible to emulsify microemulsions. To study the possi-
bility of the formation of what we shall refer to as an EME, we have studied the
effect of the addition of oil on the confined internal structure of MLO-based
aqueous solutions. In particular, we have investigated 13 the effect on the
internal structure of the solubilization of n-tetradecane with different MLO/
(MLO + oil) ratios (denoted as d %). To characterize better the self-assembly
structure of the oil-loaded MLO-based aqueous dispersions, the corresponding
bulk systems were also investigated.
Figure 5 shows the effect of TC on the internal structure at 251C of the
dispersions stabilized by F127, in comparison with the structure of the corre-
sponding nondispersed, fully hydrated bulk systems of TC + MLO + water.
In the absence of oil (Figure 5(a)), the scattering curve of the dispersion shows
six peaks at the characteristic d value for a cubic structure ( d ¼ 100) corre-
sponding to the type Pn3m (cubosomes). As soon as TC is present ( d ¼ 84,
Figure 5(b)), the scattering curve of the dispersion shows the three peaks
characteristic of a hexagonal phase. A further increase of TC content in the
dispersion ( d ¼ 57.1, Figure 5(c); d ¼ 47.6, Figure 5(d)) leads to scattering
curves with only one broad peak, as is typical for a concentrated microemul-
sion. The scattering curves of each of these dispersions with increasing TC
content correspond very well to those of the nondispersed, fully hydrated bulk
phases with the same d values. This means that the internal structure of the
particles is very similar to that of the nondispersed, fully hydrated bulk phase.
This implies that, upon increasing the TC content, we actually observe a
transition from an ECP, via an EHP, to an emulsified W/O microemulsion
(EME).
It is important to note that this good structural agreement between the
dispersed and the fully hydrated bulk phases implies that the TC/MLO mixing