Self-Assembled Liquid Particles: How to Modulate their Internal Structure - Food Colloids: Self-Assembly and Material Science - page 73

98 ° C

10 2

L 2

60 ° C

ELP

10 1

25 ° C

H 2

10 0

EHP

Pn3m

ECP

10 -1

0

1 2

3

q (nm -1 )

Figure 3 Comparison of scattering curves from the same dispersion with those from the
nondispersed bulk sample with excess water (40 wt.%) at three temperatures:
thin lines correspond to the dispersion and thick lines to the bulk phase.
Intensities were normalized by the respective MLO concentration

interior of the emulsified particles is neither destroyed by the preparation
method nor by the presence of the stabilizer F127. It also means that the
interior of the dispersed particles is still highly ordered and only slightly
affected by the dispersion procedure. The lower intensity and the slight
broadening of the peaks for the dispersion can be attributed to an interplay
of a limited size of the coherently scattering sub-volume (limited by the size of
the dispersed droplets, and also indicated by the upturn of the scattering curves
at low q-values) of a lower degree of order especially near the particle surface
caused by incorporation of F127, and of the formation of vesicles from small
parts of the MLO with F127 or possibly also small aggregates. Indeed, on
almost all of the ECP particles, attached vesicles can be observed (Figure 2);
this coexistence was also observed in previous studies on dispersed monoglyc-
erides in which F127 was used as a stabilizer. 7,16 At 251C the ECP of symmetry
Pn3m has a mean lattice parameter of 8.47 0.05 nm as determined by SAXS.
The fast Fourier transform (FFT) of the internal structure of the particles
observed by cryo-TEM (Figure 2) is compatible with the cubic Pn3m symme-
try, and it gives a lattice parameter of 8.5 nm, which is in very good

agreement with the SAXS analysis. At 601C the internal structure of the
particles was determined by SAXS to be hexagonal (EHP). This change in
internal symmetry can also be seen in the respective cryo-TEM images. 12 The
formation of an emulsified L 2 phase (ELP) is quite intriguing, but the data
clearly show that the dispersion consists mainly of submicron-sized particles
with a fluid-isotropic water +MLO-rich interior that has no long-range order.
For all the investigated temperatures, therefore, the symmetries of the internal

B