8 Magnetic Self-Assembling of Spherical Co Nanoparticles …
187
Fig. 8.2 Size distribution of Co nanoparticles synthesized by the micellar approach with different
combinations of AOT solvent/C 12 -NP solvent: xylene/hexane (S1), cyclohexane/hexane (S2),
isooctane/hexane (S3) and isooctane/cyclohexane (S4)
Table 8.2 Average diameter
(D) and size distribution (σ )
of Co NP populations
obtained with various
solvent-ligand pairs used in
the experiments. χ 12 is the
interaction parameter
calculated for the various
solvent-ligand pairs
Solvent-ligand (sample)
D (nm) σ (%) χ 12 (J mol −1 )
Octane—AOT (S5)
7.6
11
0.02375
Isooctane—AOT (S6)
7.7
12
0.02412
Decane—AOT (S4)
7.0
12
0.05058
Cyclohexane—AOT (S2) 4.6
11
0.17272
Cumene—AOT (S3)
4.7
11
0.44645
Xylene—AOT (S1)
3.9
12
0.49455
Hexane—C12 (S6)
7.7
12
0.06424
Cyclohexane—C12 (S7)
9.3
15
0.03062
impact of the solvent on the nucleation can be ruled out. However, the growth of NP
is driven by the AOT adsorption on the metal surface through the attractions between
the cobalt atoms and the polar head groups of AOT but also by AOT/AOT interactions [38]. Changing the nature of the solvent impacts the AOT solvation and then
the AOT/AOT interactions, that in turn, the final NP size. This statement is supported
by the calculation of interaction parameters χ 12 for the various solvent-AOT pairs,
using the Hansen solubility parameters [21]. In Fig. 8.3, the NP diameter is plotted
against the χ 12 parameter using a logarithmic scale. It can be seen that the NP size
decreases as the χ 12 parameter increases. A linear regression gives
log (d) = 0.944 − 0.211 log (c 12 )
187
Fig. 8.2 Size distribution of Co nanoparticles synthesized by the micellar approach with different
combinations of AOT solvent/C 12 -NP solvent: xylene/hexane (S1), cyclohexane/hexane (S2),
isooctane/hexane (S3) and isooctane/cyclohexane (S4)
Table 8.2 Average diameter
(D) and size distribution (σ )
of Co NP populations
obtained with various
solvent-ligand pairs used in
the experiments. χ 12 is the
interaction parameter
calculated for the various
solvent-ligand pairs
Solvent-ligand (sample)
D (nm) σ (%) χ 12 (J mol −1 )
Octane—AOT (S5)
7.6
11
0.02375
Isooctane—AOT (S6)
7.7
12
0.02412
Decane—AOT (S4)
7.0
12
0.05058
Cyclohexane—AOT (S2) 4.6
11
0.17272
Cumene—AOT (S3)
4.7
11
0.44645
Xylene—AOT (S1)
3.9
12
0.49455
Hexane—C12 (S6)
7.7
12
0.06424
Cyclohexane—C12 (S7)
9.3
15
0.03062
impact of the solvent on the nucleation can be ruled out. However, the growth of NP
is driven by the AOT adsorption on the metal surface through the attractions between
the cobalt atoms and the polar head groups of AOT but also by AOT/AOT interactions [38]. Changing the nature of the solvent impacts the AOT solvation and then
the AOT/AOT interactions, that in turn, the final NP size. This statement is supported
by the calculation of interaction parameters χ 12 for the various solvent-AOT pairs,
using the Hansen solubility parameters [21]. In Fig. 8.3, the NP diameter is plotted
against the χ 12 parameter using a logarithmic scale. It can be seen that the NP size
decreases as the χ 12 parameter increases. A linear regression gives
log (d) = 0.944 − 0.211 log (c 12 )