Chemistry Reference
In-Depth Information
as well as hydrophilic reagents or materials in separate sections. Thus, it is
possible to engineer the environments in those regions for specifi c applications
by wise selection of the surfactant head group and/or tail and solvent (Douglas
et al., 2008). In addition, the microscopic structure of the LC systems (i.e.,
symmetry and structural parameter such as lattice parameter) can be con-
trolled on the 1 to 5 nm scale via molecular design. Moreover, this ability can
be extended to the macroscopic scale through appropriate alignment by exter-
nal conditions.
The main advantage of synthesis in LC systems is expressed by the ability
to produce the desired materials, whose nanostructures are determined by the
rich thermotropic and lyotropic polymorphism, while their shape, size, and
dimensionality can be manipulated by selecting the templating phases of LC
(will be elaborated further).
The aim of this chapter is to provide an overview of the main research fi elds
obtainable by diverse LC phases during the last several decades. The role of
liquid crystalline systems, or more specifi c their interface abilities, in various
fi elds will be highlighted.
7.2 NANOPARTICLE SYNTHESIS—LIQUID CRYSTALLINE PHASES
PERFORM AS TEMPLATES
7.2.1
LC Surfactant Assembly as Directing Agent
The main concern in nanoparticle synthesis is the ability to form stable par-
ticles of controlled size, shape, and dispersity. Additional aim might be also to
gain nanoparticles that can be redissolved in solvents without obtaining aggre-
gation or decomposition.
The use of “hard” templates on the basis of silica (Giersig et al., 1997),
anodic aluminum oxide (Li et al., 2008; Orikasa et al., 2006; Zhou et al., 2002),
and mesoporous carbon (Dong et al., 2003; Lee et al., 2004; Xia and Mokaya,
2005) to synthesis nanoparticles has been known and used for decades.
However, the “soft” templates gained more attention over the last decade and
were found to be useful for designing novel nanomaterials such as spherical,
hollow, one-dimensional (1D) nanowires, nanorods and nanotubes, and two-
dimensional (2D) ordered arrays (Van Bommel et al., 2003). This is due to
their diversity in structures, and structure parameters with lattice constants
range from several nanometers to tens of nanometers. The soft templates can
be composed of soft compounds such as biomolecules (Zhou et al., 2009),
polymers forming gels (Shchukin et al., 2005), and amphiphilic molecules
forming emulsions or liquid crystals (Li and Coppens, 2005; Zhang et al., 2007).
The resultant nanostructured materials have potential applications in
various fi elds, such as materials science, biomedical science, electronics, optics,
magnetism, energy storage, electrochemistry, and the like (Bruchez et al., 1998;
Caruso et al., 1998; Gleiter, 2000).
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