polymerization (NMP). Among these methods, ATRP is a relative convenient and
efficient way, thus popular in synthesizing LCBCs (Yu et al. 2005b, 2007a, b).
Due to the immiscibility between the two blocks, the assembled BCs would be
microphase separated thermodynamically. Upon microphase separation, the major
part forms the continuous matrix, and the minor part would self-assemble into
ordered nanostructures. Most of the properties of LCBCs are similar with general
BCs, but LCBCs are distinguished as they reserve the advantageous properties of
LCs, such as self-assembly, long-range order in fluid, molecular cooperative motion,
anisotropic properties, and so on. These could accelerate the phase separation of
LCBCs, leading to alignment of mesogenic molecules and formation of long-range
ordered nanostructures. When mesogen-containing polymers act as continuous
matrix, the property of the LCBCs is similar with their LCP homopolymers. However, if the continuous matrix is composed of non-mesogenic polymers, the matrix
polymer contributes more to the material characteristics. For instance, PEO provide
materials with hydrophilicity, ionic electronic conductivity, and crystallinity
(Yu et al. 2011c); poly(methyl methacrylate) (PMMA) improves the optical properties of the LCBCs (Yu et al. 2007a, b).
The microphase separation of LCBCs is actually a process of self-assembly from
BCs and LCs. The property of the blocks may play an important role in the function
of materials, but the process of microphase separation is also inevitable in the
formation of nanostructures. In bulk films of LCBCs, the interplay functions
between the microphase separation and the elastic deformation of LC ordering,
known as supramolecular cooperative motion (Yu et al. 2011c, 2014), enables
them to form hierarchically molecular structures with optical functional properties,
which offers novel methods to control supramolecular self-assembled nanostructures, as shown in Fig. 8. Combining the excellent properties of LCPs with
microphase separation of BCs, photoresponsive LCBCs may find diverse applications in advanced technology as well as newly promising nanotechnology.
In LCBCs, mesogenic ordering may function as a bridge to transfer the external
force to the microphase-separated nanostructures. Proper methods could help the
formation of more regular patterns, which usually contains thermal annealing,
mechanical rubbing, photocontrolled alignment, and electric field and magnetic
field alignment. As we all know, light is one of the most convenient and cheap
energy, whose intensity, wavelength, polarization direction, and interference patterns
can be simply controlled. Totally, five kinds of alignments could be easily achieved,
nonalignment or random, homeotropic, homogenous, photoinduced thermally isotropic amorphousness, and thermally isotropic liquid (Yu and Ikeda 2011b), just as
shown in Fig. 9.
Yu et al. proposed an optical method to control a parallel alignment of PEO
nanocylinders in diblock LCBCs with smectic ordering (Yu et al. 2006a). Firstly,
PEO nanocylinder perpendicular to the direction of incident light was prepared by
supramolecular cooperative motion; then this alignment can be easily converted into
parallel alignment with the control of actinic light. This method has advantages of
clean, simple, and convenient, providing a novel approach to get regular surface
patterns even in curved surface, as shown Fig. 10 (Yu et al. 2006b).
15 Photoresponsive Liquid Crystalline Polymers
427
efficient way, thus popular in synthesizing LCBCs (Yu et al. 2005b, 2007a, b).
Due to the immiscibility between the two blocks, the assembled BCs would be
microphase separated thermodynamically. Upon microphase separation, the major
part forms the continuous matrix, and the minor part would self-assemble into
ordered nanostructures. Most of the properties of LCBCs are similar with general
BCs, but LCBCs are distinguished as they reserve the advantageous properties of
LCs, such as self-assembly, long-range order in fluid, molecular cooperative motion,
anisotropic properties, and so on. These could accelerate the phase separation of
LCBCs, leading to alignment of mesogenic molecules and formation of long-range
ordered nanostructures. When mesogen-containing polymers act as continuous
matrix, the property of the LCBCs is similar with their LCP homopolymers. However, if the continuous matrix is composed of non-mesogenic polymers, the matrix
polymer contributes more to the material characteristics. For instance, PEO provide
materials with hydrophilicity, ionic electronic conductivity, and crystallinity
(Yu et al. 2011c); poly(methyl methacrylate) (PMMA) improves the optical properties of the LCBCs (Yu et al. 2007a, b).
The microphase separation of LCBCs is actually a process of self-assembly from
BCs and LCs. The property of the blocks may play an important role in the function
of materials, but the process of microphase separation is also inevitable in the
formation of nanostructures. In bulk films of LCBCs, the interplay functions
between the microphase separation and the elastic deformation of LC ordering,
known as supramolecular cooperative motion (Yu et al. 2011c, 2014), enables
them to form hierarchically molecular structures with optical functional properties,
which offers novel methods to control supramolecular self-assembled nanostructures, as shown in Fig. 8. Combining the excellent properties of LCPs with
microphase separation of BCs, photoresponsive LCBCs may find diverse applications in advanced technology as well as newly promising nanotechnology.
In LCBCs, mesogenic ordering may function as a bridge to transfer the external
force to the microphase-separated nanostructures. Proper methods could help the
formation of more regular patterns, which usually contains thermal annealing,
mechanical rubbing, photocontrolled alignment, and electric field and magnetic
field alignment. As we all know, light is one of the most convenient and cheap
energy, whose intensity, wavelength, polarization direction, and interference patterns
can be simply controlled. Totally, five kinds of alignments could be easily achieved,
nonalignment or random, homeotropic, homogenous, photoinduced thermally isotropic amorphousness, and thermally isotropic liquid (Yu and Ikeda 2011b), just as
shown in Fig. 9.
Yu et al. proposed an optical method to control a parallel alignment of PEO
nanocylinders in diblock LCBCs with smectic ordering (Yu et al. 2006a). Firstly,
PEO nanocylinder perpendicular to the direction of incident light was prepared by
supramolecular cooperative motion; then this alignment can be easily converted into
parallel alignment with the control of actinic light. This method has advantages of
clean, simple, and convenient, providing a novel approach to get regular surface
patterns even in curved surface, as shown Fig. 10 (Yu et al. 2006b).
15 Photoresponsive Liquid Crystalline Polymers
427