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Fig. 4
Molecular structure of side chain type LC poly(siloxane) with PEO moiety
Fig. 5
Cylindrical structure formed by poly(siloxane)s having laterally substituted ne-
matogenic groups
A rigid backbone was used by Wegner to build ion-conductive PEO-
based polymers [63]. Oligo(ethylene oxide) chains were grafted from poly(
p
-
phenylene) as shown in Fig. 6. The mixtures of polymers
5
and lithium salts
show conductivities in the order of 10
-6
Scm
-1
at ambient temperature. The
ionic conductivities can be improved to the order of 10
-5
Scm
-1
by plasticiza-
tion of the materials with oligo(ethyleneglycol)-dimethylether.
Wright prepared PEO-based LC polymers having alkyl side chains
6
[64-66] as shown in Fig. 7. The alkyl side chains with linear conformation
and coiled PEO chains induce a layered nanostructure, and the complexes
of these polymers with lithium salts show conductivities in the order of
10
-7
Scm
-1
at ambient temperature.
The introduction of macroscopically oriented nanostructures is an essen-
tial approach for low-dimensional ion conduction, because the boundaries
between the domains oriented randomly disturbs anisotropic ion conduction.
However, as mentioned above, it was difficult to produce macroscopically
aligned thin films with a low density of defects and domain boundaries, and
therefore anisotropy in ionic conductivity has not been observed clearly.
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