Synthesis and characterization of novel jacketed polymers and investigation of their self assembly and application 3

Chapter 3
Synthesis and characterization of novel terphenyl-
jacketed liquid crystalline polymers

81

3.1 Introduction

Side chain LC polymers (SCLCP) with mesogenic groups laterally attached to the
polymer backbone represent an interesting series of polymers. Compared with the
conventional SCLCPs, polymer architectures with laterally attached groups give rise to
the nematic phase
1
. Wessflog et al. reported the synthesis of lateral SCLCP in 1984
2
,
followed by many reports from functional poly(siloxanes), poly(acrylate),
poly(norbornenes) derivatives
3-7
. In all cases, there are flexible spacers incorporated with
the mesogenic units on the polymer backbone. Pugh et al.
1,

7-11
demonstrated that smectic
layering could be induced in the SCLCPs with laterally attached mesogenic units. The
liquid crystalline polynorbornenes with 2, 5-bis[(4’-n-alkoxybenzoyl)oxy]benzyl
mesogens can be forced into a smectic mesophase by terminating the alkoxy groups with
fluorocarbon segments. Due to the sharp immiscibility between the aliphatic polymer
backbone and the n-perfluoroalkane, a layer type organization is formed from the micro-
separation of the two components. The immiscibility of n-alkanes and perfluoroalkanes is
proportional to their lengths. The polynorbornenes require at least eight carbon units in

the terminated chains to organize into smectic layers. Microseparation of the two
components in these molecules is weak at the minimum lengths required for smectic
layers
7, 11
. Lecommandoux et al.
4-5
reported the synthesis of poly(siloxane) derivatives
based on phenyl benzoate core terminated with alkyl chains. They demonstrated that the
polymer backbone could be segregated between the layers and also present at the middle
part of the mesogenic layer, resulting to a smectic C mesophase.
In 1987, Zhou et al.
12-17
proposed a new side chain liquid crystalline polymers, in which
mesogenic units are attached laterally to the backbone with very short spacers and

82
showed properties similar to that of the semi-rigid main chain liquid crystal polymers.
The lack of flexible spacers in the polymer lattice increased the range of observed
mesophases
16-17
. Percec et al.
19-21
reported the synthesis of monodendron jacketed side
chain liquid crystal polymers. At low degree of polymerization (DP), the conical
monodendrons assemble to produce a spherical polymer with a random-coil conformation
for the polymer backbone. With the increase of DPs, the monodendritic units are
organized into cylindrical structures with extended polymer backbone. The polymers self
organize into hexagonal columnar (Φ
h
) and cubic (Cub) lattice of the thermotropic

mesophase.
The strategy for making rigid polymers by incorporating many side groups on a flexible
polymer backbone is interesting, owing to the interplay of strong steric interaction among
the side groups and polymer backbone. Such polymers show properties of semi-rigid
main chain liquid crystal polymers with the rigidity can be adopted through tailoring the
side-chains. The organization of the rigid side group also allows to synthesize polymer
with very narrow molecular weight distribution. This new approach of synthesis of
mesogenic polymer offers a rational design for the organized supramolecular materials
4,
22-23
.
Here, we report the synthesis of a series of polymers with laterally attached mesogenic
units based on terphenyl groups with alkyl chains at the terminal position. The terphenyl
aromatic rigid core was used as mesogenic units to incorporate van der Waals interaction
and shape effects of substituents on the polymer backbone. At the same time polymers in
which the mesogenic units are connected laterally to the polymer backbone without
spacer or with very short spacer is expected to induce mesophase properties.

83

3.2 Experimental section
3.2.1 Materials and reagents
All reagents and solvents were obtained from commercial sources and used without
further purification unless mentioned otherwise. Tetrahydrofuran (THF) was distilled
from metal sodium and benzophenone under N
2
atmosphere. N,N-dimethylformamide
(DMF) was dried with 4 Å molecular sieves (Aldrich). Flash column chromatography
was performed using silica gel (60-mesh, Aldrich). Dibenzoyl peroxide (BPO) was
recrystallized from chloroform-methanol solution as glistening crystals.

3.2.2 Instrumentation

Fourier transform Infrared (FT-IR) spectra were obtained using a Perkin-Elmer 1616 FT-
IR spectrophotometer as KBr mulls.
1
H NMR,
13
C NMR spectra were recorded on a
Bruker ACF 300 MHz spectrometer. MS spectra were obtained using a Finnigan TSQ
7000 spectrometer with ESI or EI ionization capabilities. Thermogravimetric analyses
(TGA) and differential scanning calorimetry (DSC) were conducted using a TA-
SDT2960 and a TA-DSC 2920 at a heating rate of 10 °C min
-1
under N
2
environment.
Gel permeation chromatographic (GPC) analyses were done with a Waters 2696
separation module equipped with a Water 410 differential refractometer HPLC system
and Waters Styragel HR 4E columns using THF as eluent and polystyrene as standard.
The XRD patterns were recorded on a powder diffractometer with a graphite
monochromator using 1.54 Å Cu Kα wavelength at room temperature (scanning rate:
0.05
o
/s; scan range 1.5-30
o
). A Zeiss Axiolab polarized optical microscope equipped
with a Linkam LTS 350 hot stage was used to observe anisotropic textures.

84

3.2.3 Synthesis

Poly (4, 5’, 4”-trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate) (P1-C1), poly(4, 4”-
dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate) (P1-C4), poly(4, 4”-
didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate) (P1-C10), poly(1, 3-bis(4,
5’, 4”-trimethoxy[1, 1’, 4’,1”]terphenyl-2’-yloxy)-2-propyl acrylate) (P2-C1), poly(1, 3-
bis(4, 4”-dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl acrylate) (P2-
C4), and poly(1, 3-bis(4, 4”-didecyloxy-5’-methoxy [1, 1’, 4’,1”] terphenyl-2’-yloxy)-2-
propyl acrylate) (P2-C10) were synthesized using the following route shown in Scheme
3.1.

OBn
Br
Br
OCH
3
Br
OR
1
n-BuLi
THF
B(O-i-Pr)
3
1M HCL
B(OH)
2
OR
1
OBn

H
3
CO
OR
1
R
1
O
Pd(PPh
3
)
4
/Toluene/EtOH
2M K
2
CO
3 (aq)
4-C1
5-C1
6-C1
Br
Br
OH
OH
Br
Br
OBn
OH
Br
Br

OBn
OCH
3
K
2
CO
3
/DMF
BnBr
CH
3
I
NaOH/Ethanol
12
3
R
1
= CH
3
4-C4
4-C10
R
1
= C
4
H
9
R
1
= C

10
H
21
5-C4
5-C10
6-C2
6-C10


85
OH
H
3
CO
OR
1
R
1
O
Pd/C
H
2
OR
1
R
1
O
O
O
BPO/THF

OCH
3
7-C1
8-C1
OH
H
3
CO
OR
1
R
1
O
OH
Br Br
OH
OR
2
OR
2
O O
OR
2
OR
2
K
2
CO
3
/DMF Et

3
N
O O
OR
2
OR
2
n
BPO/THF
O Cl
H
3
CO
OCH
3
H
3
CO
OO
OR
1
R
1
O
H
3
CO
n
Et
3

N
O Cl
7-C1
9-C1
10-C1
7-C4
7-C10
8-C4
8-C10
P1-C1
P1-C4
P1-C10
R
1
=CH
3
R
1
=C
4
H
9
R
1
=C
10
H
21
7-C4
7-C10

9-C4
9-C10
10-C4
10-C10
P2-C1
P2-C4
P2-C10
R
2
=
R
2
=
R
2
=
H
3
CO
OC
4
H
9
C
4
H
9
O
H
3

CO
C
10
H
21
C
10
H
21
O



Scheme 3.1. Synthesis route for monomers and polymers



86

4-Methoxyphenyl boronic acid (5-C1)
In a 500 ml RB flask with a magnetic stirring bar was placed 9.35 g (50 mmol) of 4-C1
and 150 ml dry THF. The solution was cooled to -78 °C and a 1.6 M solution of butyl
lithium in hexanes (93 ml, 0.15 mol) was added slowly under nitrogen atmosphere. The
solution was warmed to RT and cooled to -78 °C, followed by the dropwise addition of
triisopropyl borate (46 ml, 0.2 mol) during a period of 2 h. After complete addition, the
mixture was warmed to RT, stirred overnight, and mixed with 2 L of deionized water.
The organic phase was collected, dried with MgSO
4
, filtered, and concentrated under
reduced pressure. The light yellow solid was recrystallized from acetone. Yield: 5.2 g

(68.4 %).
1
H NMR (300 MHz, DMSO-d
6
, δ ppm) 7.84 (s, B-OH, 2 H), 7.74-6.87 (m,
ArH, 4 H), 3.75 (s, Ar-O-CH
3
, 3 H).
13
C NMR (75.4 MHz, DMSO-d
6
, δ ppm) 160.8,
135.7, 112.8,108.3 (ArC), 54.7 (O-CH
3
). MS (ESI): m/z: 152, 134. Mp: 196 °C.
4-Butoxyphenyl boronic acid (5-C4)
Compound 5-C4 was synthesized according to the procedure described for 5-C1. Yield:
10.3 g (44.2 %).
1
H NMR (300 MHz, DMSO-d
6
, δ ppm) 7.80 (s, B-OH, 2 H), 7.73-6.85,
(m, ArH, 4 H), 3.97 (t, J = 6.3Hz, Ar-O-CH
2
-, 2 H), 1.67 (p, J = 8.4Hz, R(O)-CH
2
-, 2 H),
1.42 (p, J = 8.1 Hz, -CH
2
-, 2 H), 0.92 (t, J = 7.2 Hz, 3 H).

13
C NMR (75.4 MHz, DMSO-
d
6
, δ ppm) 160.3 136.8, 115.6, 113.5 (ArC), 66.7 (O-CH
2
-), 30.6, 18.6 (-CH
2
-), 13.6 (-
CH
3
). MS (ESI): m/z: 194.0, 166.1. Mp: 167.5 °C.
4-Decyloxyphenyl boronic acid (5-C10)
Compound 5-C10 was synthesized according to the procedure described for compound 5-
C1. 14.1g (45 mmol) of 1-bromo-4-decyloxybenzene (4-C10), 85 ml (0.135 mol) of 1.6
M butyllithilium in hexane and 41.4 ml (0.18 mol) of triisopropylborate were used and

87
the targeted compound was obtained as light yellow powder. Yield: 11.8 g (31.4%).
1
H
NMR (300 MHz, DMSO-d
6
, δ ppm) 7.70 (d, J = 8.1 Hz, ArH, 2H), 7.56 (s, B-OH, 2H),
6.78 (d, J = 8.2 Hz, ArH, 2H), 3.92 (t, J = 6.3Hz, Ar-O-CH
2
-, 2 H), 1.72 (p, J = 6.3Hz,
R(O)-CH
2
-, 2H), 1.24 (b, -CH

2
-, 14H), 0.84 (t, J = 6.0 Hz, 3H).
13
C NMR (75.4 MHz,
DMSO-d
6
, δ ppm) 158.2, 132.2, 116.3, 112.5 (ArC), 68.2 (O-CH
2
-), 31.8, 29.5, 29.4,
29.3 29.1, 25.9, 22.6, 22.0 (-CH
2
-), 13.8 (-CH
3
). MS (ESI): m/z: 278.2, 223.2, 210.2. Mp:
82.5 °C.
5’-Benzyloxy-4, 2’, 4”-trimethoxy [1, 1’, 4’, 1”] terphenyl (6-C1)
24
A 250 ml round-bottomed flask equipped with a condenser was charged with 4.0g (11
mmol) of 1-benzyloxy-2, 5-dibromo-4-methoxybenzene and 4.3 g (28 mmol) of 4-
methoxyphenyl boronic acid, 60 ml toluene, 20 ml methanol and 60 ml 2M sodium
carbonate solution. The mixture was degassed thoroughly, before the catalyst of 0.5g
tetrakis(triphenylphosphine) palladium (2 mol%) was added in dark under argon
atmosphere. The reaction mixture was degassed once more and heated to 100 °C for 48 h
in argon atmosphere, cooled to RT, and filtered. The liquid layer was separated with a
separation funnel, and the aqueous layer was extracted with toluene (100 ml × 2), toluene
fractions were combined, washed with 3 × 100 ml water, dried over MgSO
4
and filtered.
After the removal of solvent under reduced pressure, the crude product obtained was
purified using column chromatography on silica gel with hexane and dichloromethane

(4:1) mixture as eluant. Yield: 4.1g (44.3%).
1
H NMR (300 MHz, DMSO-d
6
, δ ppm) 7.60
- 6.97 (m, ArH, 15 H), 4.99 (s, Ar-CH
2
-, 2 H), 3.86 (s, Ar-O-CH
3
, 6 H), 3.80 (s, Ar-O-
CH
3
, 3 H).
13
C NMR (75.4 MHz, DMSO-d
6
, δ ppm) 158.7, 130.5, 130.4, 129.5, 129.4,
128.3, 127.5, 127.1, 117.4, 114.5, 114.2, 113.5, 113.4, 112.4 (ArC), 71.8 (O-CH
2
-), 56.2,

88
55.2 (O-CH
3
), 30.8 (O-CH
3
). MS (EI): m/z: 426.2, 335.1, 304.2, 277.1, 189.1. Mp: 148
°C.
5’-Benzyloxy-4, 4”-dibutoxy-2’-methoxy [1, 1’, 4’, 1”] terphenyl (6-C4)
The synthesis of compound 6-C4 was performed according to the procedure for

compound 6-C1. From 6.4 g (17.2 mmol) of compound 3 and 10 g (51.6 mmol) of
compound 5-C4, the desired product was obtained as a white powder. Yield: 7.2 g (81.9
%).
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.63 - 7.00 (m, ArH, 15 H), 5.02 (s, Ar-CH
2
-, 2
H), 4.05 (t, J = 3.3 Hz, Ar-O-CH
2
-, 4 H), 3.82 (s, Ar-O-CH
3
, 3 H), 1.84 (b, -CH
2
-, 4 H),
1.55 (b, -CH
2
-, 4 H), 1.06 (t, J = 2.8 Hz, -CH
3
, 6 H).
13
C NMR (75.4 MHz, CDCl
3
, δ ppm)
158.3, 151.1, 149.68, 137.4, 130.6, 130.5, 129.6, 129.5, 129.4, 129.3, 128.3, 127.5, 127.1,
118.5, 117.4, 115.3, 115.1, 114.3, 114.0, 113.3, 113.0 (ArC), 71.8 (O-CH
2
-Ar), 67.6 (O-
CH

2
-), 56.8 (O-CH
3
), 31.8, 19.2 (-CH
2
-), 13.8 (-CH
3
). MS (EI): m/z: 510.2, 419.2, 363.2,
307.1, 292.1, 199. Mp: 103 °C.
5’-Benzyloxy-4, 4”-didecyloxy-2’-methoxy [1, 1’, 4’, 1”] terphenyl (6-C10)
The synthesis of compound 6-C10 was performed according to the procedure for
compound 6-C1. From 4.1 g (11.0 mmol) of compound 3 and 9.2 g (33 mmol) of
compound 5-C10 was obtained the desired product as a white powder. Yield: 6.1 g (81.7
%).
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.60-6.98 (m, ArH, 15 H), 5.00 (s, Ar-CH
2
-O, 2
H), 4.02 (t, J = 3.6 Hz, Ar-O-CH
2
-, 4 H), 3.80 (s, Ar-O-CH
3
, 3 H), 1.84 (p, J = 4.8, -CH
2
-,
4H), 1.34 (b, -CH
2
-, 28H), 0.92 (t, J = 6.0 Hz, -CH

3
, 6H).
13
C NMR (75.4 MHz, CDCl
3
, δ
ppm) 158.3, 151.1, 149.7, 137.4, 130.6, 130.5, 130.2, 129.4, 128.3, 127.5, 117.4, 115.1,
114.0, 112.9 (ArC), 71.8 (O-CH
2
-Ar), 67.9 (O-CH
2
-), 56.8 (O-CH
3
), 31.8, 29.5, 29.4,

89
29.3, 29.2, 26.0, 22.6, 19.2 (-CH
2
-), 13.8 (-CH
3
). MS (EI): m/z: 678.4, 588.4, 447.3,
308.1, 293.1, 247.0, 199. Mp: 77 °C.
4, 5’, 4”-Trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-ol (7-C1)
To a 100 ml round-bottom flask containing 10 % Pd/C (2.0 g) in 50 ml THF was added
compound 6-C1 (3.8 g, 8.9 mmol). The flask was purged with nitrogen, and a balloon
filled with H
2
was fitted to the flask. The nitrogen was briefly evacuated from the flask,
and the H
2

was charged above the solution. The reaction mixture was stirred for 24 h at
ambient temperature and then filtered. The solid was washed with THF (3 × 25 ml), the
organic phases were combined and the solvent was then removed under reduced pressure
to yield a white powder. The resulting crude product was purified using column
chromatography on silica gel with hexane and ethyl acetate (1:4) as the eluants. Yield:
2.8 g (93.4 %).
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.63 - 6.85 (m, ArH, 10 H), 4.93 (s,
Ar-OH, 1 H), 3.88 (s, Ar-O-CH
3
, 6 H), 3.78 (s, Ar-O-CH
3
, 3 H).
13
C NMR (75.4 MHz,
CDCl
3
, δ ppm) 159.3, 158.7, 150.5, 146.4, 130.4, 130.2, 129.3, 126.6, 117.8, 114.6,
113.5, 112.5 (ArC), 56.3 (O-CH
3
), 54.3 (O-CH
3
). MS (EI): m/z: 336.1, 289.1, 261.0,
247.1, 213.1, 185.1. Mp: 161 °C.
4, 4”-Dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-ol (7-C4)
Compound 7-C4 was synthesized according to the procedure described for compound 7-
C1. From 7.0 g (13.7 mmol) of 6-C4 was obtained the product as a white powder. Yield:
5.4 g (93.6 %).

1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.52 - 6.94 (m, ArH, 10 H), 5.16 (s,
Ar-OH, 1 H), 4.03 (t, J = 4.8 Hz, Ar-O-CH
2
-, 4 H), 3.74 (s, Ar-O-CH
3
, 3 H), 1.83 (b, -
CH
2
-, 4 H), 1.54 (b, -CH
2
-, 4 H), 1.02 (t, J = 6.3 Hz, -CH
3
, 6 H).
13
C NMR (75.4 MHz,
CDCl
3
, δ ppm) 158.8, 158.3, 150.5, 146.4, 130.4, 130.1, 129.0, 126.6, 117.4, 115.2,

90
113.6 (ArC), 67.8 (O-CH
2
-), 56.8 (O-CH
3
), 31.3, 19.2 (-CH
2
-), 13.8 (-CH

3
). MS (EI): m/z:
420.3, 364.3, 298.3, 242.2, 199.1, 186.2. Mp: 115 °C.
4, 4”-Didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-ol (7-C10)
Compound 7-C10 was synthesized according to the procedure described for compound 7-
C1. From 5.8 g (8.5 mmol) of compound 6-C10 was obtained the desired product as a
white powder. Yield: 4.7 g (93.4 %).
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.52 - 6.84 (m,
ArH, 10 H), 4.94 (s, Ar-OH, 1 H), 4.02 (t, J = 5.2 Hz, Ar-O-CH
2
-, 4 H), 3.77 (s, Ar-O-
CH
3
, 3 H), 1.83 (p, J = 6.6 Hz, -R(O)-CH
2
-, 4 H), 1.54 (b, -CH
2
-, 28 H), 0.91 (t, J = 6.6
Hz, -CH
3
, 6 H).
13
C NMR (75.4 MHz, CDCl
3
, δ ppm) 159.3, 158.3, 150.5, 146.4, 130.7,
130.4, 130.1, 129.0, 117.7, 115.2, 114.0, 113.6 (ArC), 68.0 (O-CH
2

-), 56.3 (O-CH
3
), 31.8,
29.5, 29.4, 29.3, 29.0, 26.0, 22.6, 19.2 (-CH
2
-), 13.8 (-CH
3
). MS (EI): m/z: 588.3, 448.2,
308.1, 293.1, 247.0, 199. Mp: 102 °C.
4, 5’, 4”-Trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate (8-C1)
Triethylamine (1.5 ml, 9 mmol) and compound 7-C1 (1.5 g, 4.46 mmol) were dissolved
in 30 ml dry THF placed in a 100 ml RB flask. This solution was cooled to 0 °C, added a
solution of acryloyl chloride (0.72 ml, 8.9 mmol) in 4 ml THF, warmed to room
temperature and stirred for 4 h. The mixture was then filtered and the volatile
components were removed under reduced pressure. The resulting crude product was
dissolved in dichloromethane, washed with sodium bicarbonate solution, followed by
water (3 × 50 ml). The organic layer was dried over anhydrous magnesium sulfate,
filtered, and the excess solvent was removed under reduced pressure. The crude product
was further purified using flash column chromatography on silica gel column with
hexane and ethyl acetate (1:1) as eluents to yield the monomer. Yield: 1.4 g (80.4 %).
1
H

91
NMR (300 MHz, CDCl
3
, δ ppm) 7.51 - 6.89 (m, ArH, 10 H), 6.90 (d, J = 14.0 Hz, C=CH,
1 H), 6.17 (q, J = 6.9 Hz, R=CH-, 1 H), 5.88 (d, J = 10.5 Hz, C=CH, 1 H), 3.78 (s, Ar-O-
CH
3

, 9H).
13
CNMR (75.4 MHz, CDCl
3
, δ ppm) 165.2 (C=O), 158.7, 150.6, 149.3, 138.1,
137.8, 130.9, 130.7, 130.5, 130.4, 129.4, 129.3, 128.7, 128.2, 126.9, 125.8, 117.4, 117.1,
116.4, 116.1, 115.4, 115.0 (Ar-C, C=C), 57.2, 56.3 (O-CH
3
). MS (EI): m/z: 390.4, 279.2,
167.1, 149.1. Mp: 138 °C.
4, 4”-Dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate (8-C4)
Monomer 8-C4 was synthesized according to the procedure described for monomer 8-C1.
From 1.85 g (4.4 mmol) of compound 7-C4, 0.90 ml (11 mmol) of acryloyl chloride, the
desired monomer was obtained. Yield: 1.5 g (71.8 %).
1
H NMR (300 MHz, CDCl
3
, δ
ppm) 7.51-6.92 (m, ArH, 10H), 6.42 (d, J = 18.2 Hz, C=CH
2,
1H), 6,17 (q, J =10.4 Hz,
C=CH-, 1H), 5.88 (d, J = 11.7 Hz, C=CH
2
, 1H), 4.00 (t, J =3.9 Hz, O-CH
2
-, 4H), 3.82 (s,
Ar-O-CH
3
, 3H), 1.79 (p, J = 6.9 Hz, R(O)-CH
2

-, 4H), 1.54 (p, J= 6.0 Hz, -CH
2
-, 4H),
0.99 (t, J= 7.5 Hz, -CH
3
, 6H).
13
C NMR (75.4 MHz, CDCl
3
, δ ppm) 161.2 (C=O), 158.7,
158.2, 151.2, 150.4, 130.4, 129.7, 129.3, 128.9, 127.8, 118.0, 115.3, 114.3 (ArC), 69.6
(O-CH
2
-), 56.3 (O-CH
3
), 31.8, 29.5 (-CH
2
-), 13.4 (-CH
3
). MS (EI): m/z: 474.4, 420.3,
364.3, 307.2, 247.1, 199. Mp: 123 °C.
4, 4”-Didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate (8-C10)
Monomer 8-C10 was synthesized according to the procedure described for monomer 8-
C1. From 1.4 g (2.4 mmol) of compound 7-C10, 0.58 ml (7 mmol) of acryloyl chloride
was obtained the desired monomer. Yield: 0.9 g (58.9 %).
1
H NMR (300 MHz, CDCl
3
, δ
ppm) 7.52 - 6.96 (m, ArH, 10 H), 6.46 (d, J = 17.4 Hz, C=CH

2,
1 H), 6,17 (q, J =10.4 Hz,
C=CH-, 1 H), 5.89 (d, J = 11.4 Hz, C=CH
2
, 1 H), 4.02 (t, J = 3.9 Hz, Ar-O-CH
2
-, 4 H),

92
3.83 (s, Ar-O-CH
3
, 3 H), 1.82 (q, J = 6.6 Hz, -CH
2
-, 4H), 1.28 (b, -CH
2
-, 28 H), 0.91 (t, J
= 6.6 Hz, -CH
3
, 6 H).
13
C NMR (75.4 MHz, CDCl
3
, δ ppm) 164.8 (C=O), 158.6, 158.4,
154.2, 140.9, 133.4, 132.1, 130.4, 129.9, 129.8, 129.6, 129.4, 127.7, 124.5, 115.3, 114.2,
114.0 (ArC), 68.0 (O-CH
2
-), 56.3 (O-CH
3
), 31.8, 29.5, 29.4, 29.3, 29.2, 26.0, 22.6, 18.6
(-CH

2
-), 13.9 (-CH
3
). MS (EI): m/z: 642.6, 588.6, 492.5, 438.5, 307.2, 298.2, 199.1. Mp:
45 °C.
1, 3-Bis (4, 5’, 4”-trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-yl)-propan-2-ol (9-C1)
To a 250 ml three neck RB flask fitted with a reflux condenser, addition funnel and a
nitrogen inlet, DMF (100 ml), compound 7-C1 (3.2 g, 9.5 mmol), potassium carbonate
(2.1 g, 15.2 mmol) and 0.05 g KI were added. The mixture was purged with N
2
for 30
min then stirred at 80 °C for 1 h under nitrogen atmosphere. 1,3-dibromo-2-propanol
(0.47 ml, 4.5 mmol) in 5 ml DMF was added dropwise using a dropping funnel. The
reaction mixture was stirred at 80 °C for 12 h and filtered. The volatile components were
removed under reduced pressure and excessive phenol was removed by washing with 2M
sodium hydroxide and water (3 × 100 ml). The resulting crude product was purified
using column chromatography on a silica gel column with a mixture of hexane and
dichloromethane (2:3) as eluents. Yield: 2.2 g (67.1 %).
1
H NMR (300 MHz, CDCl
3
, δ
ppm) 7.52 - 6.89 (m, ArH, 20H), 4.24 (q, J = 5.7 Hz, -CH(O)-, 1H), 3. (d, J = 5.2 Hz, O-
CH
2
-C, 4H), 3.86 (s, Ar-O-CH
3
, 3H), 3.78 (s, Ar-O-CH
3
, 3H), 3.77 (s, Ar-O-CH

3
, 3H),
2.20 (b, -C-OH, 1H).
13
C NMR (75.4 MHz, CDCl
3
, δ ppm) 158.7, 151.2, 149.4, 131.4,
130.4, 129.7, 129.3, 114.6, 113.5, 112.5 (ArC), 70.5 (O-CH
2
-), 56.3, 55.2 (O-CH
3
), 36.8,
(-CH-OH). MS (EI): m/z: 728.3, 670.2, 392.2, 336.1, 289.0, 213.0, 185.1. Mp: 178 °C.
1, 3-Bis (4, 4”-dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl) propan-2-ol (9-C4)

93
Compound 9-C4 was synthesized according to the procedure described for compound 9-
C1. From 3.1 g (0.74 mmol) of compound 7-C4, 0.37 ml (3.6 mmol) of 1, 3-dibromo-
propan-2-ol was obtained the desired product. Yield: 1.4 g (43.3 %).
1
H NMR (300 MHz,
CDCl
3
, δ ppm) 7.51 - 6.88 (m, ArH, 20 H), 4.22 (q, J = 4.7 Hz, -CH(O)-, 1 H), 4.04 (q, J
= 3.1 Hz, O-CH
2
-, 8 H), 3.95 (d, J = 4.2 Hz, O-CH
2
-C, 4 H), 3.78 (s, Ar-O-CH
3

, 6 H),
2.80 (d, -C-OH, 1 H).
13
C NMR (75.4 MHz, CDCl
3
, δ ppm) 158.7, 158.2, 151.2, 150.4,
130.4, 128.9, 127.8, 118.0, 115.3, 114.3 (ArC), 70.5 (O-CH
2
-), 69.6 (O-CH
2
-C), 56.3 (O-
CH
3
), 36.8, (-CH-OH), 32.9, 19.2 (-CH
2
-), 13.8 (-CH
3
). MS (EI): m/z: 896.4, 838.5,
520.3, 476.3, 420.2, 364.2, 293.1, 199. Mp: 91 °C.
1, 3-Bis (4, 4”-didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl) propan-2-ol (9-
C10)
Compound 9-C10 was synthesized according to the procedure described for compound 9-
C1. From 3.07 g (5.2 mmol) of compound 7-C10, 0.27 ml (2.6 mmol) of 1,3-dibromide
propan-2-ol was obtained the desired product. Yield: 1.5 g (46.8 %).
1
H NMR (300 MHz,
CDCl
3
, δ ppm) 7.51 - 6.84 (m, ArH, 20 H), 4.22 (q, J = 3.4 Hz, -CH(O)-, 1 H), 4.04-3.95
(m, O-CH

2
-, 12 H), 3.78 (s, Ar-O-CH
3
, 6 H), 2.28 (d, -C-OH, 1 H).
13
CNMR (75.4 MHz,
CDCl
3
, δ ppm) 158.7, 158.2, 151.2, 150.4, 130.4, 128.9, 127.8, 118.0, 115.3, 114.3 (ArC),
70.5 (O-CH
2
-), 69.6 (O-CH
2
-C), 56.3 (O-CH
3
), 36.8, (-CH-OH), 31.8, 29.5, 29.4, 29.3,
29.2, 26.0, 22.6, 18.8 (-CH
2
-), 13.4 (-CH
3
). MS (ESI): m/z: 1232.7, 644.5, 588.4, 448.2,
308. Mp: 78 °C.
1, 3-Bis (4, 5’, 4”-trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl acrylate (10-
C1)

94
Monomer 10-C1 was synthesized according to the procedure described for monomer 8-
C1. From 1.56 g (2.6 mmol) of compound 9-C1 and 0.63 ml (7.8 mmol) of acryloyl
chloride the desired monomer was obtained. Yield: 1.1 g (5.4.0 %).
1

H NMR (300 MHz,
CDCl
3
, δ ppm) 7.52 - 6.82 (m, ArH, 20 H), 6.38 (d, J = 12.0, C=CH
2,
1 H), 6.04 (q, J
=10.4, R=CH-, 1 H), 5.82 (d, J = 10.2, C=CH
2
, 1 H), 5.35 (t, J= 4.8 Hz, -CH(O)-, 1 H),
4.09 (d, J = 4.9, O-CH
2
-, 4 H), 3.78 (s, Ar-O-CH
3
, 18 H).
13
C NMR (75.4 MHz, CDCl
3
, δ
ppm) 165.2 (C=O), 158.7, 158.6, 151.2, 149.4, 131.4,130.4, 129.3, 128.9, 127.8, 118.0,
115.3, 112.3 (ArC), 70.7 (O-CH
2
-), 67.5 (O-CH
2
-C), 56.3 (O-CH
3
). MS (EI): m/z: 782.2,
724.4, 447.2, 375.2, 336.2, 213.1. Mp: 65 °C.
1, 3-Bis (4, 4”-dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl
acrylate (10-C4)
Monomer 10-C4 was synthesized according to the procedure described for monomer 8-

C1. From 1.1 g (1.2 mmol) of compound 9-C4, 0.3 ml (3.6 mmol) of acryloyl chloride
was obtained the desired monomer. Yield: 0.85 g (74.4 %).
1
H NMR (300 MHz, CDCl
3
,
δ ppm) 7.50 - 6.79 (m, ArH, 20 H), 6.35 (d, J = 15.9 Hz, C=CH
2,
1 H), 6.07 (q, J =10.4
Hz, C=CH-, 1 H), 5.82 (d, J = 14.2 Hz, C=CH
2
, 1 H), 5.32 (t, J = 4.8 Hz, -CH(O)-, 1 H),
4.09 (b, J = 4.8 Hz, O-CH
2
-, 4 H), 4.05 (m, O-CH
2
-C, 8 H), 3.78 (s, Ar-O-CH
3
, 6 H),
1.81 (b, -CH
2
-, 8 H), 1.29 (b, -CH
2
-, 8 H), 0.87 (t, J = 6.0, -CH
3
, 12 H).
13
C NMR (75.4
MHz, CDCl
3

, δ ppm) 165.1 (C=O), 158.7, 151.2, 150.4, 130.4, 130.1, 129.9, 129.5, 128.9,
127.8, 118.0, 115.3, 114.3 (ArC), 70.5 (O-CH
2
-), 69.6 (O-CH
2
-C), 56.3 (O-CH
3
), 32.9,
19.2 (-CH
2
-), 13.8 (-CH
3
). MS (EI): m/z: 951.2, 420.3, 307.2, 247.1, 199.1. Mp: 60 °C.
1, 3-Bis (4, 4”-didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl
acrylate (10-C10)

95
Monomer 10-C10 was synthesized according to the procedure described for monomer 8-
C1. From 1.2 g (1 mmol) of compound 9-C10, 0.3 ml (3 mmol) of acryloyl chloride was
obtained the desired monomer as oil. Yield: 0.7 g (54.4 %).
1
H NMR (300 MHz, CDCl
3
,
δ ppm) 7.47 - 6.79 (m, ArH, 20 H), 6.28 (d, J = 10.6 Hz, C=CH
2,
1 H), 6.04 (q, J =10.5
Hz, C=CH-, 1 H), 5.79 (d, J = 12.2 Hz, C=CH
2
, 1 H), 5.30 (t, J = 4.8 Hz, -CH(O)-, 1 H),

4.09 (b, J = 4.8 Hz, O-CH
2
-, 4 H), 4.03 (m, O-CH
2
-C, 8 H), 3.77 (s, Ar-O-CH
3
, 6 H),
1.80 (b, -CH
2
-, 8 H), 1.29 (b, -CH
2
-, 8 H), 0.90 (t, J = 6.0, -CH
3
, 12 H).
13
C NMR (75.4
MHz, CDCl
3
, δ ppm) 168.1 (C=O), 158.0, 151.2, 150.4, 130.4, 130.1, 129.9, 129.5, 128.9,
127.8, 118.0, 115.3, 114.3 (ArC), 70.5 (O-CH
2
-), 69.6 (O-CH
2
-C), 56.3 (O-CH
3
), 31.8,
29.5, 29.4, 29.3, 29.2, 26.0, 22.6, 18.6 (-CH
2
-), 13.9 (-CH
3

). MS (ESI): m/z: 1286.2,
644.5, 588.4.
Poly(4, 5’, 4”-trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate) (P1-C1)
A 25 ml RBF containing a stirring bar was charged with 1.0 g (2.6 mmol) compound 8-
C1, 0.01 g (1 wt%) of BPO and 2 ml THF and sealed with a rubber septum. The solution
was subjected to freeze-pump-thaw cycles, then stirred at 70 ºC for 48 h. the crude
reaction mixture was precipitated from MeOH. The resulted solid was redissolved in
THF, precipitated from methanol several times and dried under high vacuum. Yield: 0.7 g
(70 %).
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.48 - 7.17 (b, ArH, 10 H), 3.85-3.71 (b, O-
CH
3,
9 H), 1.92 (b, -CH-, 1 H), 1.27 (b, -CH
2
-, 2 H). FT-IR (KBr, cm
-1
): 3055 (ArH
stretching), 2929 (-CH
2
- stretching), 1714 (ester C=O stretching), 1600, 1514, 1479 (Ar,
C=C stretching), 1249, 1164, 1096 (C-O-C stretching). M
w
:

0.9 × 10
4
, M

n
: 0.6 × 10
4
, PD:
1.7.
Poly(4, 4”-dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate) (P1-C4)

96
Polymerization of 8-C4 was performed according to the procedure described for P1-C1.
From 1.0 g (2.1 mmol) of compound 8-C4 and 0.01 g (1 wt%) of BPO was obtained 0.6 g
(60%) of the desired polymer.
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.55 - 6.62 (b, ArH,
10 H), 4.01 - 3.60 (b, O-CH
3
or O-CH
2
-
,
7 H), 1.92 (b, -CH-, 1 H), 1.57-1.05 (m, -CH
2
-,
10 H), 0.92 (b, -CH
3
, 6 H). FT-IR (KBr, cm
-1
): 3039 (ArH stretching), 2957 (-CH
2

-
stretching), 1748 (ester C=O stretching), 1608, 1524, 1489 (Ar, C=C stretching), 1291,
1177, 1026 (C-O-C stretching). M
w
:

1.76 × 10
4
, M
n
: 1.04 × 10
4
, PD: 1.7.
Poly(4, 4”-didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yl acrylate) (P1-C10)
Polymerization of 8-C10 was performed according to the procedure described for P1-C1.
From 0.85 g (1.3 mmol) of monomer 8-C10 and 0.008 g (1 wt%) of BPO was obtained
0.5 g (58.8 %) of the desired polymer.
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.55 - 6.50 (b,
ArH, 10 H), 4.01 -3.50 (b, O-CH
3
or O-CH
2
-
,
7 H), 1.90 (b, -CH-, 1 H), 1.58-1.03 (m, -
CH
2

-, 34 H), 0.89 (b, -CH
3
, 6 H). FT-IR (KBr, cm
-1
): 3038 (ArH stretching), 2924 (-
CH
2
- stretching), 1749 (ester C=O stretching), 1610, 1524,1491 (Ar, C=C stretching),
1243, 1178, 1049 (C-O-C stretching). M
w
: 0.65× 10
4
, M
n
: 0.63 × 10
4
, PD: 1.1.
Poly(1, 3-bis (4, 5’, 4”-trimethoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl acrylate)
(P2-C1)
Polymerization of 10-C1 was performed according to the procedure described for P1-C1.
From 0.64 g (0.8 mmol) of monomer 10-C1 and 0.006 g (1 wt%) of BPO was obtained
0.4 g (62.5 %) of the desired polymer.
1
H NMR (300 MHz, CDCl
3
, δ ppm) 7.64 - 7.00 (b,
ArH, 24 H), 5.45 (b, -CH(O)-, 1 H), 4.18 (b, O-CH
2
-, 4 H), 3.96 - 3.72 (b, O-CH
3

, 18 H),
1.73 (b, -CH-, 1 H), 1.27 (b, -CH
2
-, 2 H). FT-IR (KBr, cm
-1
): 3034 (ArH stretching),

97
2931 (-CH
2
- stretching), 1730 (ester C=O stretching), 1609, 1521, 1491 (Ar, C=C
stretching), 1292, 1179,1031 (C-O-C stretching). M
w
:

1.46× 10
4
, M
n
: 1.07 × 10
4
, PD: 1.4.
Poly(1, 3-bis (4, 4”-dibutoxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl
acrylate) (P2-C4)
Polymerization of 10-C4 was performed according to the procedure described for P1-C1.
From 0.65 g (0.68 mmol) of monomer 10-C4 and 0.006 g (1 wt%) of BPO was obtained
0.4 g (61.5 %) of the desired polymer.
1
H NMR (300 MHz, CDCl
3

, δ ppm) 7.64 - 6.93 (b,
ArH, 24 H), 5.30 (b, -CH(O)-, 1 H), 4.06 (b, O-CH
2
-, 4 H), 3.96-3.65 (b, O-CH
3
and O-
CH
2
-, 14 H), 1.67 (b, -CH-, 1 H), 1.56-0.95 (m, -CH
2
-, 18 H), 0.88 (b, -CH
3
, 12 H). FT-
IR (KBr, cm
-1
): 3038 (ArH stretching), 2958(-CH
2
- stretching), 1748 (ester C=O
stretching), 1609, 1524, 1491 (Ar, C=C stretching), 1242, 1177, 1048 (C-O-C stretching).
M
w
:

0.98× 10
4
, M
n
: 0.63× 10
4
, PD: 1.6.

Poly(1, 3-bis (4, 4”-didecyloxy-5’-methoxy [1, 1’, 4’, 1”] terphenyl-2’-yloxy)-2-propyl
acrylate) (P2-C10)
Polymerization of 10-C10 was performed according to the procedure described for P1-
C1. From 0.6 g (0.47mmol) of monomer 10-C10 and 0.006 g (1 wt%) of BPO was
obtained 0.46 g (76.7 %) of the desired polymer.
1
H NMR (300 MHz, CDCl
3
, δ ppm)
7.90 - 6.85 (b, ArH, 20 H), 5.34 (b, -CH(O)-, 1 H), 4.00 (b, O-CH
2
-, 4 H), 3.98 - 3.65 (b,
O-CH
3
and O-CH
2
-, 14 H), 1.66 (b, -CH-, 1 H), 1.50-1.08 (m, -CH
2
-, 66 H), 0.88 (b, -
CH
3
, 12 H). FT-IR (KBr, cm
-1
): 3037 (ArH stretching), 2924 (-CH
2
- stretching), 1734
(ester C=O stretching), 1609, 1524, 1493 (Ar, C=C stretching), 1244, 1178,1056 (C-O-C
stretching). M
w
:

1.67× 10
4
, M
n
: 1.04× 10
4
, PD: 1.6.

98
3.3 Results and Discussion
3.3.1 Synthesis of polymers
The polymers were synthesized through radical polymerization from the appropriate
monomers. The concentration of initiator BPO was 1.0 mol % based on the amount of the
monomer used. The structures of all monomers and polymers prepared in our work were
characterized by
1
H NMR and FTIR. Figure 3.1 illustrates two representative
1
H NMR
spectra of monomer 8-C4 and polymer P1-C4. In the
1
H NMR spectra of monomer 8-C4,
for example, the signals appearing in the range of δ 7.51- 6.92 correspond to those in
aromatic protons. The signals at δ 3.82 are assigned to protons of methoxy groups while
the multiplets at δ 4.00 correspond to the protons of –OCH
2
- in alkyl chains. The triplets
at δ 6.42, 6.17 and 5.71 are characteristic of acrylic carbon double bond protons. It is
noted that in the spectrum of polymer P1-C4, these three signals disappears. The absence

of a C=C band at 1640 cm
-1
in the FTIR spectrum of P1-C4 also indicates that the
monomer has reacted to form a polymer.
3.3.2 Thermal characterization

The thermal stability of polymers in nitrogen was investigated by thermogravimetric
analysis (TGA) and the results are depicted in Figure 3.2. The polymers show a weight
loss at 285 °C for P2-C4, 287 °C for P1-C4, 296 °C for P1-C1 and 307 °C for P2-C1,
306 °C for P1-C10, 312 °C for P2-C10. This may be due to the similar structure of the
polymer backbone. Thermally induced phase transition behaviors of the polymers were
evaluated using differential scanning caloritry (DSC) in nitrogen atmosphere. The DSC
traces are shown in Figure 3.3.


99

Figure 3.1.
1
H NMR spectra of monomer 8-C4 and polymer P1-C4 in CDCl
3

0 100 200 300 400 500 600 700 800
0
20
40
60
80
100
P1-C1

p2-C1
P1-C4
P2-C4
P1-C10
P2-C10
weight percent (%)
Temperature (
o
C)

Figure 3.2. TGA traces of P1-C1, P1-C4, P1-C10, P2-C1, P2-C4, P2-C10 measured in
a nitrogen atmosphere at a heating rate 10 °C

/min.

100
-50 0 50 100 150 200 250
P2-C10
P1-C10
P2-C4
T
n
57.4 (
o
C)
T
iso
76.2 (
o
C)

T
g
-19.7 (
o
C)
T
iso
81.1 (
o
C)
T
g
24.8 (
o
C)
T
g
20.4 (
o
C)
P1-C4
T
iso
156.4 (
o
C)
T
g
64.8 (
o

C)
P2-C1
T
g
63.1 (
o
C)
P1-C1
T
g
77.2 (
o
C)
Heat flow (mW)
Temperature (
o
C)

Figure 3.3. Second heating differential scanning calorimetry curves for P1-C1, P1-C4,
P1-C10, P2-C1, P2-C4, P2-C10 measured in a nitrogen atmosphere at a heating rate 10
°C

/min.

P1-C1 exhibits a glass transition (T
g
) at 77.2 °C. With the increase of the flexible alkyl
chains in the terminal position on the terphenyl rigid rod, the glass transition temperatures
of P1-C4 and P1-C10 decrease to 64.8 °C

and 24.8

°C, respectively. Similarly, P2-C1
shows a glass transition at 63.1 °C

whereas the T
g
s of P2-C4 and P2-C10 decrease to
20.4 and –19.7 ºC. It is noted that besides the glass transition, polymer P1-C4, P1-C10
and P2-C10 exhibit mesophase properties at different temperatures. P1-C4 undergoes an
isotropization at 156.4 °C

whereas P1-C10 shows a mesophase change at 81.1 °C. P2-
C10 exhibits a small thermal transition at 57.4 °C, and then undergoes an isotropization

101
at 76.2

°C. The decrease of the isotropization temperatures is proportional to the increase
of the alkyl chain length on mesogenic units.

3.3.3 Polarized optical microscopy study
The mesophase was identified using polarized optical microscope investigation. Polymers
(P1-C4, P1-C10 and P2-C10) showed the homotropic textures. POM microphotographs
of the mesomorphic textures of these novel polymers are shown in Figure 3.4.
When the isotropic liquid of P2-C10 was cooled to 56 °C, a branched fan texture was
observed. According to the literatures
25-26
, the texture is considered of SmB phase. The
micrograph Figure 3(b) was taken after heating the mesophase to 75 °C, and the observed

fibrous textures indicate the formation of nematic mesophase. Polymer P1-C10 showed a
typical focal-conic fan texture of smectic A phase
26
when cooled to 72 °C

from an
isotropic melt of P1-C10 (Figure 3.4 c), whereas Schlieren texture was observed for P1-
C4 (Figure 3.4 d) while cooling the isotropic melt to 125 °C, and no other mesophases
were observed on prolonged cooling. No birefringent textures were found from the P1-
C1, P2-C1 and P2-C4 during cooling.


a

b

102

c

d

Figure 3.4. Polarized optical micrographs of the textures observed on cooling of (a) P2-
C10 to 56 °C; (b) P2-C10 to 75 °C; (c) P1-C10 to 72 °C; and (d) P1-C4 to 125 °C

from
the isotropic liquid with a cooling ratio of 0.5 °C

/min.

From DSC and POM results, it is noted that the polymer P1-C10 and P2-C10 form a
lamellar layer structure in the mesophase while P1-4 only shows a nematic phase. It is
also reporteded that the side chain liquid crystalline polymers with mesogenic groups
laterally attached to the polymer backbone prefer to form nematic mesophases
12-14
. The
steric crowding of the side chains forces the backbone into an extended conformation
with the mesogens organizing parallel to the polymer backbone. Therefore the centers of
the mesogenic units are staggered inside the polymer lattice to form a nematic phase.
The terphenyl aromatic rigid cores are attached to the polymer backbone without any
spacer, therefore the rigid mesogenic units are not only force the polymer backbone to
take an extended conformation, but also organize close to the backbone, and form a rigid
core. This enhances the rigidity of the polymer backbone, and the micro-separation
between rigid core and the flexible alkyl chains is the main driving force for the polymers
to pack in a more ordered pattern
27-28
. The DSC results show that the long alkyl chains at

103
the terminal position on the rigid aromatic core are necessary to form a layer structure.
P1-C1 and P2-C1 with methyl groups on the side chain didn’t exhibit any mesophase,
whereas P1-C4 showed a nematic phase
12-15
. Only polymer with terminal alkyl chains
such as P1-C10 and P2-C10 showed a smectic lattice.

3.3.4 X-ray diffraction analysis
XRD measurements were carried out to collect more information on self-organization
and the packing modes of the novel polymers. The polymers were annealed in the oven at
about 60 °C for two days then cooled down quickly to room temperature before

measurement. X-ray diffraction patterns for all polymers are shown in Figure 3.4, The d-
spacing distance was derived using the Bragg’s law d = nλ/2sin(θ) (λ = 1.54 Å). The
reflection angle 2θ and the space distance d are listed in Table 3.1.


Table 3.1. Peak Angles in degree and d Spacings in Å for the Polymers
Polymer
2θ
1
°/ d
1
Å 2θ
2
°/ d
2
Å 2θ
3
°/ d
3
Å 2θ
4
°/ d
4
Å
P2-C10
4.16/21.2 8.32/10.6 10.25/8.6 19.7/4.5
P1-C10
4.74/18.6 10.40/8.5 21.14/4.2
P1-C4
7.84/11.3 10.50/8.4 20.08/4.4

P2-C4
20.2/4.4
P2-C1
20.0/4.4
P1-C1
20.56/4.3


104
4 8 12 16 20 24
P2-C1
P2-C4
8.4 A
o
11.3 A
o
8.5 A
o
18.6 A
o
8.6 A
o
10.6 A
o
21.2 A
ο
P2-C10
P1-C10
P1-C4
P1-C1

Relative intensity (a.u)
2-theta(degree)

Figure 3.5. X-ray diffraction patterns for the jacketed liquid crystalline polymers at room
temperature.

The XRD diffraction pattern of P2-C10 shows three sharp reflections in small and middle
angle regions at a 2θ value of 4.16, 8.32 and 10.2°, from which d spacings of 21.2Å, 10.6
Å and 8.6 Å are derived. It is noted that polymer P2-C10 affords two X-ray diffraction
peaks in small angle with d spacings ratio of 1:1/2. This d spacing ratio is indicative of a
smectic structure, corresponding to first- and second-order Bragg reflections from
smectic layers
29,30
. P1-C10 affords two sharp reflections in the small and middle angle
region at 2θ = 4.74
o
and 10.4
o
, from which d spacings of 18.6 and 8.5 Å are derived. The
existence of long-range order in the polymer lattice rules out the possibility of the
nematic phase formation and reinforces the smectic lattice structure. For P1-C4, the
diffraction patterns exhibits one sharp reflection at 2θ = 7.84
o
and small peak at 2θ =
10.5
o
, from which d spacings of 11.3Å and 8.4Å are derived. The profiles of the P1-C1,

105