Synthesis and Alignment of Nanostructured Materials Using Liquid Crystals - Self-Assembled Supramolecular Architectures: Lyotropic Liquid Crystals - page 201

(a) (c)

(b)

H II

B B

no field

(d) (e) (f)

L α

no field B B

(g) (h) (i)

Pn3m

B B

no field

Figure 7.9 2D small-angle neutron scattering (SANS) patterns of: (upper row) H II ,
(middle row) L α , and (lower row) Pn3m mesophases containing amyloid fi brils coated
with iron-oxide magnetic nanoparticles. Labels (a), (d), and (g) represent the SANS
measurements in the absence of the external magnetic fi eld. Labels (b), (c), (e), (f), (h),
and (i) indicate the measurements performed under exposure to 1.1T external mag-
netic fi eld applied in two different directions tilted by 90° (Amar-Yuli et al., 2011).

were detected both prior (Fig. 7.9g) and after (Figs. 7.9h and 7.9i) exposure
to the same magnetic fi eld.
The mechanism for this magnetically assisted orientation, introduced by the
authors, was that the columnar hexagonal and lamellar phases nucleating from
the isotropic fl uid upon cooling and in the presence of aligned fi brils, used
these latter as heterogeneous nucleating surfaces, leading to a preferential
orientation of the resulting mesophase.
One of the common explored classes of nanomaterials is metal nanopar-
ticles. In general, in the fi rst step of metal nanoparticle synthesis, a metal salt