Chemistry Reference
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Utilizing these methods, the ionic conductivity of a number of aqueous
LLC systems based on commercially available amphiphiles has been meas-
ured. For example, the “inverse” L phase of the sodium dodecylsulfate/
pentanol/water system has been studied under shear conditions and found to
exhibit anisotropic conductivity, resulting in a material with a conductivity
range of approximately 1 to 2.5
10
-3
Scm
-1
[81]. The ionic conductivities of
the L and micellar phases of the potassium laurate/decanol/D
2
O system [82],
and the lithium triflate-loaded regular H
I
phase of an oligo(EO) surfactant-
templated silicate nanocomposite have also been measured [83] resulting in
conductivities that range from 3 to 6
×
10
-2
Scm
-1
and 10
-4
to 10
-7
Scm
-1
,
respectively. It has also been determined that the ionic conductivity of an
L phase is dependent on its thickness [82, 84].
Recently, non-water-based LLC materials have taken the forefront of LLC-
based ion conducting materials. Instead of using water as the polar solvent
to form ordered LLC phases, room-temperature ionic liquids (RTILs) have
emerged as the solvent of choice for improved composition stability in form-
ing LLC assemblies (i.e., no evaporative solvent loss), and also for improving
ion conductivity in the LLC polar domains. RTILs are polar, molten organic
salts under ambient conditions that are typically based on substituted imi-
dazolium, phosphonium, ammonium, and related organic cations, which are
complemented by a relatively non-basic and non-nucleophilic large anion [85].
RTILs possess negligible vapor pressures; and as such, offer a new non-volatile
solvent medium for organization of LLCs. As RTILs are very different from
solvents like water, fundamental work has been concerned with understand-
ing how small-molecule surfactants organize around and in RTILs [86, 87].
A number of RTIL-based LLC systems have already been specifically designed
to serve as anisotropic, ion-conducting nanocomposite materials. For example,
×
Fig. 12
Examples of ion-conductive LLC systems that form L phases with imidazolium-
based RTILs as the polar liquid phase [89, 90]
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