The MJLCPs synthesized by Zhou et al. (1989) exhibit banded textures (Xu et al.
1993a, b) under PLM usually observed in oriented rigid or semirigid polymers such
as MCLCPs (Wang and Zhou 2004), confirming that these polymers have significant
chain rigidity. Actually, these polymers are the first side-chain polymers that show
banded textures. Many other MJLCPs also display similar banded textures (Tu et al.
2000; Ye et al. 2004; Zhou et al. 1993).
The chain stiffness of polymer 2 (Chart 1) was studied with static light scattering
and viscometry (Wan et al. 1995). The persistence length was estimated to be about
12 nm, and the α-value in the Mark-Houwink-Sakurada equation was determined to
be 0.82. These results indicate that the polymer has a wormlike chain conformation
in dilute solution, similar to MCLCPs.
Small-angle X-ray scattering (SAXS) was used to study the conformation of a
mesogen-jacketed polyelectrolyte, poly[sodium 2,5-bis(4
0 -sulfophenyl)styrene]
(PSBSS, polymer 7 in Chart 1) in aqueous solution (Qu et al. 2014). The precursor
of PSBSS was synthesized by atom transfer radical polymerization (ATRP),
resulting in a narrow MW distribution (MWD). PSBSS in the aqueous solution
has a cylindrical conformation, with a persistence length of 11.5 nm.
MW Dependence
For a rodlike MJLCP with a stretched backbone, its length increases almost linearly
with increasing molecular weight (MW) and thus affects the aspect ratio of the
rodlike supramolecular mesogen. Therefore, the LC behavior of the MJLCP has a
strong MW dependence (Chen et al. 2010). The typical MJLCP PMPCS shows such
an MW-dependent phase behavior (Ye et al. 2004). When its MW measured by GPC
is lower than 1.0 Â 10
4 Da, PMPCS is amorphous; when the MW is in the range of
1.0 Â 10
4
–1.6 Â 10
4 Da, it forms a stable Col n LC phase upon heating at high
temperatures above its glass transition temperature (T g ); when the MW is higher than
1.6 Â 10
4 Da, it is also liquid crystalline after being annealed at temperatures higher
than T g , exhibiting a Col hn phase. Many other MJLCPs, such as PBPCS (polymer
5 with n = 4 in Chart 1) (Zhao et al. 2006) and PMVBP (polymer 8 in Chart 1)
(Zhang et al. 2014), also exhibit similar MW-dependent phase behaviors.
Unusual Phase Behavior
Many as-prepared MJLCP samples are amorphous and enter into LC phases when
they are heated or annealed at temperatures higher than their T g values. If the
isotropization temperatures of the LC phases are too high to be observed under
experimental conditions, the LC phases will be retained during further heating or
subsequent cooling processes. However, unusual phase behaviors have been
observed in some MJLCPs (Chen et al. 2010), similar to the reentrant phase
behaviors owing to the rod-coil conformational transformation in polypeptides
(Lin 1997) and the columnar-isotropic transition in polydialkoxyphosphazenes
(Papkov et al. 1992). Such a behavior was first found in PHPCS (polymer 5 with
n = 6 in Chart 1) (Yu et al. 2003a), which became isotropic liquid again after being
36
Z. Shen
1993a, b) under PLM usually observed in oriented rigid or semirigid polymers such
as MCLCPs (Wang and Zhou 2004), confirming that these polymers have significant
chain rigidity. Actually, these polymers are the first side-chain polymers that show
banded textures. Many other MJLCPs also display similar banded textures (Tu et al.
2000; Ye et al. 2004; Zhou et al. 1993).
The chain stiffness of polymer 2 (Chart 1) was studied with static light scattering
and viscometry (Wan et al. 1995). The persistence length was estimated to be about
12 nm, and the α-value in the Mark-Houwink-Sakurada equation was determined to
be 0.82. These results indicate that the polymer has a wormlike chain conformation
in dilute solution, similar to MCLCPs.
Small-angle X-ray scattering (SAXS) was used to study the conformation of a
mesogen-jacketed polyelectrolyte, poly[sodium 2,5-bis(4
0 -sulfophenyl)styrene]
(PSBSS, polymer 7 in Chart 1) in aqueous solution (Qu et al. 2014). The precursor
of PSBSS was synthesized by atom transfer radical polymerization (ATRP),
resulting in a narrow MW distribution (MWD). PSBSS in the aqueous solution
has a cylindrical conformation, with a persistence length of 11.5 nm.
MW Dependence
For a rodlike MJLCP with a stretched backbone, its length increases almost linearly
with increasing molecular weight (MW) and thus affects the aspect ratio of the
rodlike supramolecular mesogen. Therefore, the LC behavior of the MJLCP has a
strong MW dependence (Chen et al. 2010). The typical MJLCP PMPCS shows such
an MW-dependent phase behavior (Ye et al. 2004). When its MW measured by GPC
is lower than 1.0 Â 10
4 Da, PMPCS is amorphous; when the MW is in the range of
1.0 Â 10
4
–1.6 Â 10
4 Da, it forms a stable Col n LC phase upon heating at high
temperatures above its glass transition temperature (T g ); when the MW is higher than
1.6 Â 10
4 Da, it is also liquid crystalline after being annealed at temperatures higher
than T g , exhibiting a Col hn phase. Many other MJLCPs, such as PBPCS (polymer
5 with n = 4 in Chart 1) (Zhao et al. 2006) and PMVBP (polymer 8 in Chart 1)
(Zhang et al. 2014), also exhibit similar MW-dependent phase behaviors.
Unusual Phase Behavior
Many as-prepared MJLCP samples are amorphous and enter into LC phases when
they are heated or annealed at temperatures higher than their T g values. If the
isotropization temperatures of the LC phases are too high to be observed under
experimental conditions, the LC phases will be retained during further heating or
subsequent cooling processes. However, unusual phase behaviors have been
observed in some MJLCPs (Chen et al. 2010), similar to the reentrant phase
behaviors owing to the rod-coil conformational transformation in polypeptides
(Lin 1997) and the columnar-isotropic transition in polydialkoxyphosphazenes
(Papkov et al. 1992). Such a behavior was first found in PHPCS (polymer 5 with
n = 6 in Chart 1) (Yu et al. 2003a), which became isotropic liquid again after being
36
Z. Shen