Karthaus et al. (1992) synthesized the amphiphilic triphenylene derivatives 20, 21
in order to study the difference between structures displayed by monomeric and
polymeric amphiphilic discotic liquid crystalline triphenylene derivatives in the bulk
state and in the Langmuir-Blodgett (LB) films. An edge-on arrangement of the
discotic molecules within a double-layer packing of columns parallel to the solid
was found in the LB films of both compounds. Polymer 21 in bulk state formed a less
ordered nematic phase as compared to highly ordered columnar phase exhibited by
monomer 20.
OR
OR
RO
RO
OR
OR
RO
RO
O
O
O
O
20; R = C 5 H 11
21; R = C 5 H 11
O
O
HO
OH
( ) 6
( ) 6
( ) 6
O
O
( ) 6
x
Block copolymers are known to form a range of microphase-separated structures
like lamellae, hexagonal-packed cylinders, cubic-packed spheres and bicontinuous
cubic gyroid morphology. By combining blocks with distinct characteristics, it is
possible to tailor the properties of block copolymers. Keeping this in mind, Boden
et al. (Boden et al. 1999, 2001; Abeysekera et al. 2003) prepared discotic main-chain
diblock and triblock copolymers containing one triphenylene block with one or two
polyethyleneoxy blocks. These polymers were found to show columnar phase at
room temperature. The copolymer 22 clears at 86.5
C and 23.1 clears at 66.4
C.
The triblock copolymer 23 undergoes microphase separation, giving a nanostructured material consisting of a hexagonal array of poly(ethylene oxide) rods in the
matrix of columnar liquid crystal (Table 7).
Imrie and co-workers (Stoeva et al. 2013) reported the electrolyte properties of
these triblock copolymers on doping with lithium perchlorate. The polymer
Table 7 Phase behavior of main-chain polymers based on triphenylene 22–23 (Ref 14: Boden
et al. 1999; Ref 15: Boden et al. 2001; Ref 16: Abeysekera et al. 2003)
Mesogen
n
m
Z
Phase transitions
Ref
22
16
10–12
23.1
16
10–12
CH 2
23.2
12
4–13
CO
Cr 43.9 Col h 72.1 I
15
23.3
33
4–13
CO
Cr 38–48 Col h 85.7 I
15
23.4
45
12
CO
Cr 39.2 Col h 84.1 I
16
23.5
45
12
CO
Cr 38.4 Col h 85.7 I
16
3 Liquid Crystalline Polymers Derived from Disc-Shaped Molecules
69
in order to study the difference between structures displayed by monomeric and
polymeric amphiphilic discotic liquid crystalline triphenylene derivatives in the bulk
state and in the Langmuir-Blodgett (LB) films. An edge-on arrangement of the
discotic molecules within a double-layer packing of columns parallel to the solid
was found in the LB films of both compounds. Polymer 21 in bulk state formed a less
ordered nematic phase as compared to highly ordered columnar phase exhibited by
monomer 20.
OR
OR
RO
RO
OR
OR
RO
RO
O
O
O
O
20; R = C 5 H 11
21; R = C 5 H 11
O
O
HO
OH
( ) 6
( ) 6
( ) 6
O
O
( ) 6
x
Block copolymers are known to form a range of microphase-separated structures
like lamellae, hexagonal-packed cylinders, cubic-packed spheres and bicontinuous
cubic gyroid morphology. By combining blocks with distinct characteristics, it is
possible to tailor the properties of block copolymers. Keeping this in mind, Boden
et al. (Boden et al. 1999, 2001; Abeysekera et al. 2003) prepared discotic main-chain
diblock and triblock copolymers containing one triphenylene block with one or two
polyethyleneoxy blocks. These polymers were found to show columnar phase at
room temperature. The copolymer 22 clears at 86.5
C and 23.1 clears at 66.4
C.
The triblock copolymer 23 undergoes microphase separation, giving a nanostructured material consisting of a hexagonal array of poly(ethylene oxide) rods in the
matrix of columnar liquid crystal (Table 7).
Imrie and co-workers (Stoeva et al. 2013) reported the electrolyte properties of
these triblock copolymers on doping with lithium perchlorate. The polymer
Table 7 Phase behavior of main-chain polymers based on triphenylene 22–23 (Ref 14: Boden
et al. 1999; Ref 15: Boden et al. 2001; Ref 16: Abeysekera et al. 2003)
Mesogen
n
m
Z
Phase transitions
Ref
22
16
10–12
23.1
16
10–12
CH 2
23.2
12
4–13
CO
Cr 43.9 Col h 72.1 I
15
23.3
33
4–13
CO
Cr 38–48 Col h 85.7 I
15
23.4
45
12
CO
Cr 39.2 Col h 84.1 I
16
23.5
45
12
CO
Cr 38.4 Col h 85.7 I
16
3 Liquid Crystalline Polymers Derived from Disc-Shaped Molecules
69