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Nanostructured emulsion based on H
2
(
φ
= 80,
δ
= 80)
(a)
(b)
(c)
20
μ
m
20
μ
m
10
μ
m
(d)
(e)
(f)
5
μ
m
10
μ
m
2
μ
m
Nanostructured emulsion based on L
2
(
φ
= 80,
δ
= 50)
Figure 6.16
Microstructural investigations of nanostructured emulsions. Optical
micrographs (a) and (d) show birefringence from the lipid phase. Confocal micrographs
clearly show the lipid network (in light gray) in H
2
[(b) and (c)], and EME [(e) and (f)
nanostructured emulsions. In images (e) and (f) the network appears denser than in
(d) because of hydrogel formation in the aqueous regions of the EME-based emulsion.
Arrows indicate droplet inhomogeneities, which represent large water droplets
(
m). The water droplets responsible for emulsion stability [as in (d)] are in the
range of 2-8
∼
20
μ
μ
m in size.
In our case, the nanostructured emulsions were stable above 74% water,
but for lower values of the dispersed phase, the stability is presumed to
be given by the LC phase itself (being rather viscous). Only in the case of
EME as the structure-forming unit was the stability below 80% water too
low, leaving the nanostructured emulsions more prone to phase—especially
oil— separation.
The most novel things about these W/O-nanostructured emulsions are:
(1) they do not require an external stabilizing agent, and (2) their structural
hierarchy (Fig. 6.18) can be tuned on a very broad scale. Thus, these emul-
sions have very good potential for applications in materials science and
biotechnology.
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