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pH, and temperature; although it is also possible to alter conventional param-
eters, such as concentration, particle size, and shape, for this purpose. More
importantly, it is possible to adjust the surface characteristics (with respect to
interaction with emulsion medium, in other words, their wettability and inter-
particle interactions) (Muller et al., 2010a,b; Salonen et al., 2008, 2010b).
Natural and synthetic clay-based systems are well known for forming nano-
composites with inorganic and organic (especially polymeric) materials
(Agrawal et al., 2004; Gupta and Bhattacharya, 2008). Clays have a platelike
structure in which an octahedral metal hydroxide layer is sandwiched between
two tetrahedral silica layers. Due to the characteristic high-aspect ratio (1 nm
thick and
30 nm mean diameter), large surface area, and surface functional-
ization, they are ideal for enhancing these materials' properties and for stabi-
lizing Pickering emulsions. Ashby and Binks (2000) were the fi rst to focus on
specifi c effects of such clay nanoparticles as stabilizers. However, Salonen
et al. (2008) and Muller et al. (2010b) have also explored similar clay pellets
for stabilizing structured emulsions such as ISAsomes. They have demon-
strated that the ISAsomes can be stabilized by using Laponite (Laponite XLG
from Southern Clay Products, Gonzales, Texas) particles regardless of the
internal LC structure (Muller et al., 2010a; Salonen et al., 2008). The natural
clay Montmorillonite (SPV Wyoming provided from Comptoir des Minéraux,
France), having larger-diameter pellets, can also stabilize ISAsomes to a similar
extent as that of Laponite (Guillot et al., 2009a). Figure 6.4 shows the small-
∼
3
70:30/0.5
90:10/0.5
100:0/0.5
50:50/0.5
2
1
0,0
0,5
1,0
1,5
q (nm
−1
)
2,0
2,5
3,0
Figure 6.4
Laponite- (clay) stabilized ISAsomes. SAXS pattern from ISAsomes with
varying proportions of DU and TC. Each curve is labeled with its DU : TC ratio
together with the Laponite concentration: 100 : 0/0.5 (Pn3m, open circles), 90 : 10/0.5 (H
2
,
open squares), 70 : 30/0.5 (Fd3m, up triangles), and 50 : 50/0.5 (EME, down triangles).
[From Salonen et al. (2008) .]
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