Chemistry Reference
In-Depth Information
Decane
Dodecane
Tetradecane
Octadecane
(a)
(b)
0.5
0.4
1E-3
0.3
0.2
0.1
1E-4
0.0
10
12
14
16
18
0
1000
2000
Time (s)
3000
4000
5000
Number of C-atoms of oil
0.00050
0.00045
(c)
(d)
0.003
0.00040
0.00035
0.00030
0.002
0.00025
0.00020
0.00015
0.00010
0.00005
0.00000
0.001
0.000
0
2
4
6
8
10
0
1
2
3
Concentration of F127 (wt %)
Concentration of dispersed phase (wt %)
Figure 6.8
Factors affecting the transfer kinetics of ISAsomes. (a) Disappearance of
the H
2
phase for various oils. The curves are used to determine the corresponding rate
constants plotted in (b) against the number of C atoms in the oil used. Rate constants
determined independently for varying amounts of dispersed phase (lipid or lipid
oil)
and F-127 concentrations are shown in (c) and (d), respectively. [Figures (b), (c), and
(d) are modifi ed from Moitzi et al. (2007).]
+
1 0
− 4
s
− 1
for
fi rst-order kinetics process. The decay rate was found to be 4.94
×
the curve shown in Figure 6.7c.
Here, the principal questions were: What is the process actually leading to
equilibration of the fi nal nanostructure? Does it occur via fusion/coalescence
of nanostructured droplets (ISAsomes) or via transfer of oil molecules through
the aqueous medium? Studies in this direction (e.g., Moitzi et al., 2007) show
that the latter process is much more likely and is supported by the following
observations.
In similar experiment to that shown in Figure 6.7, various rate constants
were obtained by changing the type of oil from decane to octadecane, as shown
in Figure 6.8a. The rate constant decreased linearly with C-chain length of
the oil molecules (Fig. 6.8b). This indicates that the transfer of oil between
ISAsomes depends on the solubility of the oil in water, which decreases with
increasing C-chain length of the oil molecule. Thus, the material transfer
process is rate limited by the transfer of oil through the water phase.
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