then polymerized using photoinitiator to LC network. When a strip of this thin LC
network film is placed on a glass surface, enabling free movement without any
constraints, the polymeric film exhibits a caterpillar-like motion. When the film is
clamped at one end, oscillations are observed. Two edges of the film can be glued,
which exhibit a tube formation with buckling and continuous deformation during
irradiation. By gluing two edges of the film separately, continuous travelling wave is
generated during irradiation. By using continuous light source, the initiated wave
continuously regenerates and propagates in a repeating, snakelike motion. By this
motion small object can be transported over the distance.
Ferroelectric Liquid Crystals
Ferroelectric liquid crystals (FLCs) have a chiral smectic-C phase, S
Ã
C , having
each layer with permanent electric polarization confined in the plane of the layer
and perpendicular to the director tilted by an angle from the layer normal. The
presence of chirality in a bulk FLC allows the rotation of the directors of the
successive layers, and the polarization vectors are cancelled by induced helical
structure over a pitch length. Therefore, the spontaneous polarization of FLCs can
be made useful by suppressing the helical structure in the S
Ã
C phase by aligning
molecules in one direction. The FLCs have important advantages over other liquid
crystals (LCs) for use in electronic and photonic devices in respect of fast
switching speed of FLCs in an electric field. The surface-stabilized FLCs can be
made by using rubbed surface (Clark and Lagerwall 1980). An azobenzenecontaining monomer is polymerized in FLC host and irradiated with linearly
polarized light, which results in photoalignment in an anisotropic polymer network
that achieves both the induction and stabilization of the FLC orientation in the S
Ã
C
phase (Zhao and Paiement 2001).
When chiral dimethacrylate and diacrylate monomers dissolved in a FLC host (Min.
1% concentration) are polymerized under linearly polarized irradiation, the monomers
are able to induce a bulk alignment of FLC in the SC
à phase (Zhao et al. 2003).
At higher percentage the polymer network being too dense the bulk alignment is not
possible. When azobenzene moieties in main chain are connected via shorter spacers,
less efficient photoinduced orientation is observed due to reduction in mobility. Generally, the chirality on monomers affords stronger interaction between azobenzene
groups and the FLC in the chiral S
Ã
C phase that facilitates bulk alignment of the latter
via the action of the former.
Light-Sensitive Microcapsules Based on Liquid Crystalline Polyester
Microcapsules are known to encapsulate various kinds of substances, such as gases,
liquids, and solids, which are called as core material. The coating substances,
known as shell, can also be selected from a wide variety of natural or synthetic
polymers, depending on its function. Microcapsules are designed in such a way that
412
A. B. Samui
network film is placed on a glass surface, enabling free movement without any
constraints, the polymeric film exhibits a caterpillar-like motion. When the film is
clamped at one end, oscillations are observed. Two edges of the film can be glued,
which exhibit a tube formation with buckling and continuous deformation during
irradiation. By gluing two edges of the film separately, continuous travelling wave is
generated during irradiation. By using continuous light source, the initiated wave
continuously regenerates and propagates in a repeating, snakelike motion. By this
motion small object can be transported over the distance.
Ferroelectric Liquid Crystals
Ferroelectric liquid crystals (FLCs) have a chiral smectic-C phase, S
Ã
C , having
each layer with permanent electric polarization confined in the plane of the layer
and perpendicular to the director tilted by an angle from the layer normal. The
presence of chirality in a bulk FLC allows the rotation of the directors of the
successive layers, and the polarization vectors are cancelled by induced helical
structure over a pitch length. Therefore, the spontaneous polarization of FLCs can
be made useful by suppressing the helical structure in the S
Ã
C phase by aligning
molecules in one direction. The FLCs have important advantages over other liquid
crystals (LCs) for use in electronic and photonic devices in respect of fast
switching speed of FLCs in an electric field. The surface-stabilized FLCs can be
made by using rubbed surface (Clark and Lagerwall 1980). An azobenzenecontaining monomer is polymerized in FLC host and irradiated with linearly
polarized light, which results in photoalignment in an anisotropic polymer network
that achieves both the induction and stabilization of the FLC orientation in the S
Ã
C
phase (Zhao and Paiement 2001).
When chiral dimethacrylate and diacrylate monomers dissolved in a FLC host (Min.
1% concentration) are polymerized under linearly polarized irradiation, the monomers
are able to induce a bulk alignment of FLC in the SC
à phase (Zhao et al. 2003).
At higher percentage the polymer network being too dense the bulk alignment is not
possible. When azobenzene moieties in main chain are connected via shorter spacers,
less efficient photoinduced orientation is observed due to reduction in mobility. Generally, the chirality on monomers affords stronger interaction between azobenzene
groups and the FLC in the chiral S
Ã
C phase that facilitates bulk alignment of the latter
via the action of the former.
Light-Sensitive Microcapsules Based on Liquid Crystalline Polyester
Microcapsules are known to encapsulate various kinds of substances, such as gases,
liquids, and solids, which are called as core material. The coating substances,
known as shell, can also be selected from a wide variety of natural or synthetic
polymers, depending on its function. Microcapsules are designed in such a way that
412
A. B. Samui