be controlled on the different length and time scales before polymerization. This
chapter describes the fundamental characteristics and recent research interests of
anisotropic LC networks, elastomers, and gels fabricated using a variety of
programmed RMs.
Keywords
Reactive mesogen · Liquid crystal · Oriented film · Self-assembly ·
Photopolymerization
Definitions
Reactive mesogen (RM) is often used with liquid crystal (LC) monomers even
though sometimes RM does not exhibit the LC phase itself. The mutual polymerization of the reactive functional groups allows the phase structure to be fixed,
stabilizing the system in a specific direction and position sequence. This could
lead to a variety of LC thin films with vertical, planar, splayed, twisted, and patterned
alignment. In this circumstance, we put together this chapter as an overview on the
RM and the resulting physical properties under the framework of uniaxially oriented
state in the macroscopic length scale.
Introduction
Liquid crystalline (LC) phase exhibits the combined physical properties of fluid-like
viscosity and crystal-like optical anisotropy. The partially ordered LC soft materials
can form the thermodynamically stable mesomorphic states between their crystalline
and isotropic (I) phases. Depending on the anisotropic shape of LC molecules, LC
can be classified into calamitic (rod-shaped) and discotic (disc-shaped) LC molecules. Phase transition temperatures and optical properties of the LC molecules are
mainly governed by the type of mesogenic groups as well as the length of flexible
spacers (Kim et al. 2016a). Since the physical, electrical, and optical properties of the
LC materials are closely related to the molecular organizations and conformations,
the manipulation of material states has been one of the most fundamental and
intriguing research fields for material scientists and engineers. It is well known
that the calamitic LC molecules often form nematic (N), cholesteric (NÃ), and
smectic (Sm) phases. Longer flexible units tend to favor the formation of Sm phases,
in which the odd-even effects on the phase transition are obvious. The discotic LC
molecules, on the other hand, reveal the columnar, discotic N, and chiral discotic
phases. In recent years, much attention has been paid to the discotic phases because
of the excellent charge-transporting capability and the efficient photo- or electroluminescent properties (Kumar 2014). Since the LC molecules themselves form multidomains without external stimuli, the various alignment methods are commonly
employed to obtain the macroscopically oriented single domain (Kim et al. 2017).
96
D.-Y. Kim et al.
chapter describes the fundamental characteristics and recent research interests of
anisotropic LC networks, elastomers, and gels fabricated using a variety of
programmed RMs.
Keywords
Reactive mesogen · Liquid crystal · Oriented film · Self-assembly ·
Photopolymerization
Definitions
Reactive mesogen (RM) is often used with liquid crystal (LC) monomers even
though sometimes RM does not exhibit the LC phase itself. The mutual polymerization of the reactive functional groups allows the phase structure to be fixed,
stabilizing the system in a specific direction and position sequence. This could
lead to a variety of LC thin films with vertical, planar, splayed, twisted, and patterned
alignment. In this circumstance, we put together this chapter as an overview on the
RM and the resulting physical properties under the framework of uniaxially oriented
state in the macroscopic length scale.
Introduction
Liquid crystalline (LC) phase exhibits the combined physical properties of fluid-like
viscosity and crystal-like optical anisotropy. The partially ordered LC soft materials
can form the thermodynamically stable mesomorphic states between their crystalline
and isotropic (I) phases. Depending on the anisotropic shape of LC molecules, LC
can be classified into calamitic (rod-shaped) and discotic (disc-shaped) LC molecules. Phase transition temperatures and optical properties of the LC molecules are
mainly governed by the type of mesogenic groups as well as the length of flexible
spacers (Kim et al. 2016a). Since the physical, electrical, and optical properties of the
LC materials are closely related to the molecular organizations and conformations,
the manipulation of material states has been one of the most fundamental and
intriguing research fields for material scientists and engineers. It is well known
that the calamitic LC molecules often form nematic (N), cholesteric (NÃ), and
smectic (Sm) phases. Longer flexible units tend to favor the formation of Sm phases,
in which the odd-even effects on the phase transition are obvious. The discotic LC
molecules, on the other hand, reveal the columnar, discotic N, and chiral discotic
phases. In recent years, much attention has been paid to the discotic phases because
of the excellent charge-transporting capability and the efficient photo- or electroluminescent properties (Kumar 2014). Since the LC molecules themselves form multidomains without external stimuli, the various alignment methods are commonly
employed to obtain the macroscopically oriented single domain (Kim et al. 2017).
96
D.-Y. Kim et al.