conversion, and the MWD is symmetrical and relatively narrow. With further
polymerization, the MWD changes to multimodal, indicating the formation of a
branched structure. In order to form a stable LC phase, the MW of the branched
PMPCS needs to exceed a minimum value, while the feed molar ratio of MPCS to
CMS has to be higher than 30. The branched structure has a depressing effect on
liquid crystallinity of PMPCS. As a result, the branched polymer only shows a Col n
phase.
Reversible Addition-Fragmentation Chain Transfer (RAFT)
Polymerization
In preparation of water-soluble semirigid thermoresponsive polymers with relatively
narrow MWDs, Zhang et al. synthesized a series of MJLCPs, poly[bis
(N-hydroxyisopropyl pyrrolidone) 2-vinylterephthalate] (PHIPPVTA), using
RAFT polymerization (Liu et al. 2012). The polymers are liquid crystalline when
the MW is high enough. The cloud point of the polymer increases with increasing
MW, opposite to the trend in flexible thermoresponsive polymers. In addition, the
polymer has a lower cloud point in D 2 O than in H 2 O. Using the similar synthetic
approach, they also synthesized three series of MJLCP-based water-soluble thermoresponsive polymers with relatively narrow MWDs, poly[bis(N-(2-hydroxypropyl)
pyrrolidone) 2-vinylterephthalate] [P(2-HPPVTA)], poly[bis(N-(1-methyl-2hydroxyethyl) pyrrolidone) 2-vinylterephthalate] [P(1-M-2-HEPVTA)], and poly[bis
(N-hydroxypropyl pyrrolidone) 2-vinylterephthalate] (PHPPVTA) (Liu et al. 2013).
OOC
COO
H 3 CO
OCH 3
CuBr, Sp
PhCl, 90
o
C
Ia
Ib
rod-like PMPCS chain
central core
O
O
O
O
O
O
Br
Br
Br
CH 2
O
O
O
Br
O
O
Br
Br
Ia
Ib
Scheme 6 Synthesis of tri-arm star-shaped PMPCS by ATRP (Wang et al. 2005)
2 Mesogen-Jacketed Liquid Crystalline Polymers: Molecular Design and. . .
47
polymerization, the MWD changes to multimodal, indicating the formation of a
branched structure. In order to form a stable LC phase, the MW of the branched
PMPCS needs to exceed a minimum value, while the feed molar ratio of MPCS to
CMS has to be higher than 30. The branched structure has a depressing effect on
liquid crystallinity of PMPCS. As a result, the branched polymer only shows a Col n
phase.
Reversible Addition-Fragmentation Chain Transfer (RAFT)
Polymerization
In preparation of water-soluble semirigid thermoresponsive polymers with relatively
narrow MWDs, Zhang et al. synthesized a series of MJLCPs, poly[bis
(N-hydroxyisopropyl pyrrolidone) 2-vinylterephthalate] (PHIPPVTA), using
RAFT polymerization (Liu et al. 2012). The polymers are liquid crystalline when
the MW is high enough. The cloud point of the polymer increases with increasing
MW, opposite to the trend in flexible thermoresponsive polymers. In addition, the
polymer has a lower cloud point in D 2 O than in H 2 O. Using the similar synthetic
approach, they also synthesized three series of MJLCP-based water-soluble thermoresponsive polymers with relatively narrow MWDs, poly[bis(N-(2-hydroxypropyl)
pyrrolidone) 2-vinylterephthalate] [P(2-HPPVTA)], poly[bis(N-(1-methyl-2hydroxyethyl) pyrrolidone) 2-vinylterephthalate] [P(1-M-2-HEPVTA)], and poly[bis
(N-hydroxypropyl pyrrolidone) 2-vinylterephthalate] (PHPPVTA) (Liu et al. 2013).
OOC
COO
H 3 CO
OCH 3
CuBr, Sp
PhCl, 90
o
C
Ia
Ib
rod-like PMPCS chain
central core
O
O
O
O
O
O
Br
Br
Br
CH 2
O
O
O
Br
O
O
Br
Br
Ia
Ib
Scheme 6 Synthesis of tri-arm star-shaped PMPCS by ATRP (Wang et al. 2005)
2 Mesogen-Jacketed Liquid Crystalline Polymers: Molecular Design and. . .
47