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limited solely to these functions [119, 171]. New ideas for the use of LLCs are
being conceived regularly, necessitating a need for a “bottom-up” approach
to materials design. Novel materials and chemistry are needed for LLCs to
meet application-specific demands. In particular, three areas of opportunity
have presented themselves, which may drastically alter and expand the func-
tional capabilities of LLC materials. These include (i) the further development
of Q phase LLC materials; (ii) the incorporation of functional groups into LLC
mesogens other than catalytic moieties; and (iii) the use of RTILs to form
LLC phases instead of water. These three areas of research offer gateways for
radically new designs and applications for LLC-based materials
Q phases are already one of the most promising, research-intensive LLC-
based drug delivery systems because of the superior diffusion and access
characteristics afforded by their 3-D interconnected nanopore systems [129,
151-154]. Initial results have also shown that Q-phase LLC materials also
possess superior transport and access properties in membrane applications
compared to L and H
II
phases [170]. This phenomenon could translate into
the design of superior LLC-based heterogeneous catalysts or bulk sorbents, as
the interconnected nanochannels may provide more open pathways for better
accessibility and selective molecular and/or ion diffusion. However, design-
ing functional amphiphiles that can readily form useful Q-phase materials is
not a straightforward task. To date, less than a handful of LLC monomers are
known in the literature that can be polymerized in Q phases [172-175].
The ability to design LLC mesogens containing functional units other than
catalytic moieties has the potential for extending the use of functionalized
LLC phases and LLC polymer materials beyond catalysis. For example, the
incorporation of other types of functional, task-specific chemical units onto
LLC starting materials could lead to NF membranes that could perform mo-
lecular level separations using mechanisms other than simple size exclusion.
Similarly, such materials could broaden the use of nanoporous LLC systems
into as of yet unimagined application areas.
Ion conduction has been the only application examined thus far for RTIL-
based LLC materials. However, given the seemingly exponential expansion of
research into RTILs as new reaction solvents, new gas sorption media, and new
ion-conductive materials [85, 88-90], it appears to be only a matter of time be-
fore RTILs make a significant impact on the design of functional LLC materials.
RTILs promise to open the door to new applications for LLC materials.
References
1. Collins PJ (1990) Liquid crystals: nature's delicate state of matter. Princeton Univer-
sity Press, Princeton
2. Stegemeyer H (ed) (1994) Liquid crystals. Springer, New York
3. Tiddy GJT (1980) Phys Rep 57:1
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