Self-Assembled Liquid Particles: How to Modulate their Internal Structure - Food Colloids: Self-Assembly and Material Science - page 79

5.3.2 Micellar Cubosomes and Transformation from Hexosomes
to EME
This section focuses on the recent discovery of an Fd3m phase (reverse
discontinuous micellar cubic), which is formed in the MLO + water + TC
system at a specific TC/MLO weight ratio.
Figure 9 shows the SAXS scattering curves that were obtained from disper-
sions in which the d value was varied from 100 down to 62.5 at 251C. For
d ¼ 100 (without oil) a dispersed system is formed with a confined inverted
bicontinuous cubic structure, belonging to the Pn3m space group. On increas-
ing the oil content (decreasing d ), the internal ordered phase of the particles
becomes an inverse hexagonal H 2 . Intriguingly, a further increase of the TC
concentration in the dispersion to d ¼ 71.4 gives rise to a scattering curve that
shows more than seven peaks. These peaks are in the characteristic ratio for a
discontinuous micellar cubic structure of the type Fd3m (micellar cubosomes or
emulsified MCP). Remarkably, this is not found in the absence of TC. At
higher oil concentrations, the scattering curve shows only one broad peak,
which is typical of that for a concentrated microemulsion phase. The present
work proves that the structural transformation in the dispersed particles from
H 2 (hexosomes) to the W/O microemulsion system (EME) may be indirect,
occurring gradually via an emulsified intermediate phase (see Figure 9). We
denote this new type of emulsified particles as micellar cubosomes. The Fd3m
cubic phase consists of a three-dimensional periodically ordered complex
packing of two different types of discrete inverse micelles, both quasispherical.
In this phase, the unit cell contains 8 larger inverse micelles of symmetry 43 m

311

220

111

10

222

400

331

422

333+511

440

620 533

100

EME

444

531

442

622

Micellar Cubosomes

1

110

110

111 200

Hexosomes

200

211

220

221

Cubosomes

0 1 2 3 4

q (nm -1 )

Figure 9 Effect of n-tetradecane content on the scattering curves of MLO-based emul-
sified systems at 251C: d ¼ 100 (cubosomes), d ¼ 78.1 (hexosomes), d ¼ 71.4
(micellar cubosomes), and d ¼ 62.5 (EME). Peaks are identified by their
Miller indices