units may be present along the main chain (main-chain LCPs, MCLCPs) or as
pendant groups attached to the side (side-chain LCPs, SCLCPs) using soft spacers
such as methylene units as shown in Fig. 4a, b (Mao and Ober 1998; Walther and
Finkelmann 1996). In SCLCPs, the mesogen can be attached to the backbone end-on
or laterally. In MCLCPs, the presence of mesogens along the backbone imparts
rigidity to the polymer chain whereas in SCLCPs the backbone is more flexible
because the interactions with the mesogens are decoupled by the flexible spacers.
This difference in the type of LCPs leads to differences in their properties, e.g., mainchain LCPs have higher modulus and transition temperatures compared to the sidechain LCPs. LCPs also exhibit mesophases similar to their small M n counterparts
although polymerization imparts better order and higher transition temperatures to
LCPs. Although both Sm and N LC phases are observed in MCLCPs, Sm structures
are more common in SCLCPs. The flexibility of polymer backbone facilitates
packing of the mesogens into layers.
Mesogen-jacketed liquid crystalline polymers (MJLCPs) are a unique class of
SC-LCPs in which the mesogens are attached laterally along the polymer backbone
without a spacer. Finkelmann et al. proposed that lateral attachment of mesogens
along the polymer backbone restricts the rotational motion of the mesogen around its
long axis and facilitates LC ordering (Hessel and Finkelmann 1986). By decoupling
the mesogens and the backbone using spacers, LC ordering can be achieved in
laterally attached LCPs although the backbone adopts a statistical chain conformation (Ban et al. 2014; Chen et al. 2010; Liang et al. 2010; Pan et al. 2007; Yu 2014;
Zhou et al. 1987, 1988, 1989, 2010; Zhu et al. 2014). In MJ-LCPs, the size of the
mesogen is larger than the backbone repeat unit. In such a situation, packing of the
a
b
mesogen
spacer
c
H 2
C
H
C
C
O
O
OCH 3
C
O
O
H 3 CO
m
Fig. 4 Molecular architecture
of (a) main chain, (b) side
chain, and (c) mesogenjacketed liquid crystalline
polymers
7 Structure and Assembly of Liquid Crystalline Block Copolymers
181
pendant groups attached to the side (side-chain LCPs, SCLCPs) using soft spacers
such as methylene units as shown in Fig. 4a, b (Mao and Ober 1998; Walther and
Finkelmann 1996). In SCLCPs, the mesogen can be attached to the backbone end-on
or laterally. In MCLCPs, the presence of mesogens along the backbone imparts
rigidity to the polymer chain whereas in SCLCPs the backbone is more flexible
because the interactions with the mesogens are decoupled by the flexible spacers.
This difference in the type of LCPs leads to differences in their properties, e.g., mainchain LCPs have higher modulus and transition temperatures compared to the sidechain LCPs. LCPs also exhibit mesophases similar to their small M n counterparts
although polymerization imparts better order and higher transition temperatures to
LCPs. Although both Sm and N LC phases are observed in MCLCPs, Sm structures
are more common in SCLCPs. The flexibility of polymer backbone facilitates
packing of the mesogens into layers.
Mesogen-jacketed liquid crystalline polymers (MJLCPs) are a unique class of
SC-LCPs in which the mesogens are attached laterally along the polymer backbone
without a spacer. Finkelmann et al. proposed that lateral attachment of mesogens
along the polymer backbone restricts the rotational motion of the mesogen around its
long axis and facilitates LC ordering (Hessel and Finkelmann 1986). By decoupling
the mesogens and the backbone using spacers, LC ordering can be achieved in
laterally attached LCPs although the backbone adopts a statistical chain conformation (Ban et al. 2014; Chen et al. 2010; Liang et al. 2010; Pan et al. 2007; Yu 2014;
Zhou et al. 1987, 1988, 1989, 2010; Zhu et al. 2014). In MJ-LCPs, the size of the
mesogen is larger than the backbone repeat unit. In such a situation, packing of the
a
b
mesogen
spacer
c
H 2
C
H
C
C
O
O
OCH 3
C
O
O
H 3 CO
m
Fig. 4 Molecular architecture
of (a) main chain, (b) side
chain, and (c) mesogenjacketed liquid crystalline
polymers
7 Structure and Assembly of Liquid Crystalline Block Copolymers
181