Chemistry Reference
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Fig. 6
Molecular structure of poly(
p
-phenylene) derivatives with a PEO group in their side
chains
Fig. 7
Complexation of PEO-based LC polymers with lithium salts, and their nanostruc-
ture
Kato, Ohno and coworkers have used an in-situ photopolymerization tech-
nique to overcome the problem of the alignment of LC polymers [67-69].
Two-dimensionally ion-conductive polymer films (
7
)wereobtainedby
photopolymerization of aligned monomer complexes. The monomer self-
assembles into layered nanostructures, in which PEO moieties form nano-
segregated ion transporting channels. The complex of the LC monomer with
LiOSO
2
CF
3
exhibits a smectic A phase. UV irradiation of the homeotrop-
ically aligned complex results in the formation of a free-standing film, as
shown in Fig. 8 [67]. The film shows ionic conductivities in the order of
10
-6
Scm
-1
in the direction parallel to the layers, which is approximately
5000-times higher than that perpendicular to the layers. The value of the
conductivity is not so high because the segmental motion of the PEO moi-
ety is restricted between the polymer backbone and the mesogenic parts.
The conductivity can be enhanced to the order of 10
-3
Scm
-1
by introducing
a PEO moiety at the terminal of the side chain (
8
, Fig. 9) [68]. The cor-
responding acrylate monomer complex with LiOSO
2
CF
3
(0.05 mol % to the
oxyethylene) was polymerized in the smectic A phase at 60
◦
CbyUVirradi-
ation. Polymer
8
complexed with LiOSO
2
CF
3
exhibits the glass transition
at -45
◦
C and the solid-smectic A transition at 161
◦
C. The isotropization
temperature is observed at 202
◦
C. At room temperature, conductivity in
the range of 10
-3
Scm
-1
to the direction parallel to the layer is observed,
even though the complex forms a solid state. These high ionic conductivi-
ties of the complex of
8
can be ascribed to the liquid-like layers in the solid
oriented film.
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