A new series of two-ring-based side chain liquid crystalline polymers: Synthesis and mesophase characterization

Article abstract of DOI:10.1071/CH13090

A new series of side chain liquid crystalline polymers containing a core, a butamethylenoxy spacer, ester groups, and terminal alkoxy groups were synthesised and their structures were confirmed. The core was constructed with two phenyl rings and an ester linking unit. All the polymers were characterised by hot-stage polarising optical microscopy, differential scanning calorimetry, variable temperature X-ray diffraction, thermogravimetric analysis, and gel permeation chromato-graphy. The polymers were found to be liquid crystalline. The nematic and smectic A (SA) phases were observed for the homologues with short-terminal chains (C2 and C6), whereas the homologues with longer chains (C8 to C12) exhibited a smectic C phase. The thermal stability of the polymers was found to be in the range of 293 to 326°C and the molecular weights of the polymers were found to vary from 6×103 to 1.3×10⁴.

Full text of DOI:10.1071/CH13090

CSIRO PUBLISHING
Aust. J. Chem. 2013, 66, 667–675
Full Paper
http://dx.doi.org/10.1071/CH13090
A New Series of Two-Ring-Based Side Chain Liquid
Crystalline Polymers: Synthesis and Mesophase
Characterization
A B E
, ,
C E
,
Tanneru Narasimhaswamy, Jarugala
Goddeti Siva Mohan Reddy,
B
B
A
Jayaramudu, Emmanuel Rotimi Sadiku, Konduru Mohana Raju,
D
and Suprakas Sinha Ray
A
Department of Polymer Science and Technology, Sri Krishnadevaraya University,
Anantapur, 515003, India.
B
Chemical, Metallurgical and Material Engineering, Polymer Technology Division,
Tshwane University of Technology, Pretoria 0001, South Africa.
C
Polymer Division, Council of Scientific and Industrial Research - Central Leather
Research Institute, Adyar, Chennai, 600020, India.
D
DST/CSIR National Centre for Nano-structured Materials, Council for Scientific and
Industrial Research, Pretoria 0001, South Africa.
E
Corresponding authors. Email: smreddyg@gmail.com, tnswamy99@hotmail.com
A new series of side chain liquid crystalline polymers containing a core, a butamethylenoxy spacer, ester groups, and
terminal alkoxy groups were synthesised and their structures were confirmed. The core was constructed with two phenyl
rings and an ester linking unit. All the polymers were characterised by hot-stage polarising optical microscopy, differential
scanning calorimetry, variable temperature X-ray diffraction, thermogravimetric analysis, and gel permeation chromato-
graphy. The polymers were found to be liquid crystalline. The nematic and smectic A (SA) phases were observed for the
homologues with short-terminal chains (C2 and C6), whereas the homologues with longer chains (C8 to C12) exhibited a
smectic C phase. The thermal stability of the polymers was found to be in the range of 293 to 3268C and the molecular
weights of the polymers were found to vary from 6 ꢀ 103 to 1.3 ꢀ 104.
Manuscript received: 22 February 2013.
Manuscript accepted: 15 March 2013.
Published online: 27 May 2013.
or azomethine linkages.[14–16] Earlier studies on two-ring poly-
acrylates with ether linking units between the spacer and core
units, exhibited nematic and smectic A (SA) phases that have
high isotropic temperatures.[16–19] In this context, in the present
work, a series of new polymers were synthesised in order to
study the structure–property relationship, improve the phase
stability, and to reduce the isotropic temperature. Introducing
ester linkages between the spacer and the two-ring-based core
resulted in nematic, SA, and smectic C (SC) phases with a wide
temperature range, and reduced the isotropic temperature of the
polymers, significantly.
Introduction
Thermotropic side chain liquid crystalline polymers (SCLCP)
have become important in view of their interesting material
properties.[1] The ability to form films, fibres, and sheets, char-
acteristic of synthetic polymers, and their tendency to respond to
externalstimuli, typicalofliquidcrystals, areconvenientlyshared
in SCLCP.[2] In contrast to main chain liquid crystalline poly-
mers, SCLCP are easy to solubilise in common solvents at room
temperature and their mesophase temperatures are relatively low
(,ambient).[3] Owing to this, SCLCP have attracted a lot of
attentionfromresearchersaroundtheworld.Thepioneeringwork
of Finkelmann, Plate, and others resulted in the formation of
SCLCP.[4–7] Interms ofmolecular design, typical SCLCP usually
consist ofa flexible acrylic/methacrylic backbone witha spacer, a
core, and terminalalkyl/alkoxychains.[8,9] Attemptstosynthesise
SCLCP without spacers have largely been unsuccessful.[10,11]
The design and developments related to SCLCP have been
thoroughly reviewed[12,13] and it is clear that most of the systems
investigated make use of either acrylic/methacrylic or siloxane
as back bones. Typically, a spacer and back bone (acrylic/
methacrylic) are linked through ether (C–O–C) linkages, while
the core (mostly two-ring based) is constructed with either ester
Results and Discussion
Synthesis of Liquid Crystalline Polymers
A series of acrylic acid-based monomers containing a two-ring
core, a butamethylenoxy spacer, ester linking units, and various
terminal alkoxy groups was synthesised as shown in Scheme 1.
The solution polymerisation of these monomers resulted in good
yields of the corresponding SCLCP and they were characterised
by using standard analytical techniques in order to confirm the
chemical structure. The FT-IR spectrum of a representative
Journal compilation Ó CSIRO 2013
www.publish.csiro.au/journals/ajc

668
G. S. M. Reddy et al.
H
C
H
H
H2C
H2C
H2C
O
O
O
O
O
HO
O
O
O
O
O
HO
O
O
(CH2)4
O
(CH2)4
(CH2)4
O
O
O
D
B
OH
C
OH
A
O
O
O
O
O
O
(CH2)n
O
O
O
CH3
O
(CH2)n
O
(CH2)n
(CH3
O
O
2 (a–e)
(CH2)n
CH3
(CH3
(CH2)n
1 (a–e)
CH3
n ϭ 1, 5, 7, 9, 11
3 (a–e)
4 (a–e)
A) DMF, SOCl2, reflux, 1h; triethylamine, methyl ethyl ketone, 0ЊC, 3h. B) Pd/C, H2, THF, room temp., 24h.
C) N,NЈ-Dicyclohexylcarbodiimide, 4-dimethylaminopyridine, dichloromethane/THF 0ЊC, 12h.
D) Benzoyl peroxide, 1,4-dioxane, 70ЊC 12h.
Scheme 1. Synthetic strategy of two-ring monomers and polymers.
noticed at 1606and 1510cmꢁ1. The C–H stretchingof the methyl
and methylene groups are observed at 1451 and 1394cmꢁ1. The
C–O–C stretching vibrations of the ester and ether groups
(asymmetric and symmetric) are observed at 1268, 1207, and
1164 cmꢁ1 respectively. These features and the absence of an
absorption at 1634cmꢁ1, which is typical for the C¼C stretching
of an acrylic unit, clearly indicated the formation of polymers.
In Fig. 2, the 1H NMR spectrum of the polymer shows broad
signals due to the highly viscous nature of the sample and geminal
and vicinal couplings of protons from neighbouring monomeric
units. The peaks that appear at 4.09 and 4.33 ppm are from
oxymethylene protons. A peak at 2.31 ppm is assigned to the
backbone methine proton, while those that appear at 1.80 and
1.44 ppm arecontributedbythe methyleneprotons ofthebackbone
as well as the spacerand terminal methyl protons, respectively. The
disappearance of peaks at 5.82, 6.11, and 6.41 ppm, which are
characteristic of acrylic –CH2 and –CH protons present in the
monomer, unambiguously supports the formation of polymers.
The 13C NMR spectra of the monomer and respective polymer
are shown in Fig. 3. The spectra show two kinds of peaks,
i.e. intense and sharp peaks and low intensity and broad peaks.
These contrasting features indicate not only the difference in the
chemical environment, but also their location in the polymer.
A group of low intensity and broad signals centred at 174.55 and
172.82 ppm are assigned to the carbonyl ester of the acrylic unit.
In the monomer spectrum, the signal pertaining to the carbonyl
ester of the acrylic unit is noticed as a sharp and moderately
intense line at 166.33ppm. The increase in the chemical shift
values in the polymer and broadening of the line for the carbonyl
ester clearly suggest that these carbons are sensitive to configu-
rational heterogeneity. The spectrum also shows medium inten-
sity peaks in the region of 160–165ppm, which arises from the
quaternary carbons of the phenyl ring present in the core. Four
100
90
80
70
60
4000
3500
3000
2500
2000
1500
]
1000
500
Wavenumbers [cmϪ1
Fig. 1. FT-IR spectrum of poly-{4-[(acryloyloxybutoxy)carbonyl]phenyl
4-ethoxybenzoate} (4a).
polymer is given in Fig. 1. The C–H stretching absorption of the
back bone, spacer, and terminal chain units of the polymer is
noticed as a broad peak at 2957 cmꢁ1. A very intense absorption
centred at 1737 cmꢁ1 is attributed to the carbonyl ester groups
present in the polymer. The intensity of this absorption clearly
supports the presence of a large number of carbonyls in the
polymer. In addition, the appearance of one absorption signal for
three carbonyl esters suggests that their chemical environment is
not significantly different. Ring skeletal vibrations (C¼C) are

Thermotropic Side Chain Liquid Crystalline Polymers
669
3a
4a
8
6
4
2
0
1H Chemical shift [ppm]
Fig. 2. 1H NMR spectra of monomer 3a and polymer 4a.
3a
160
120
80
40
0
4a
160
120
80
40
0
13C Chemical shift [ppm]
Fig. 3. 13C NMR spectra of monomer 3a and polymer 4a.
sharplinesintheregionbetween113and133 ppmarecontributed
by the methine carbons of two phenyl rings. The spectrum shows
three peaks at 64.06, 64.27, and 63.91 ppm, arising from the
oxymethylene carbons. Among them, the one seen at 64.27 ppm
is of low intensity and broad, while the other two are sharp, which
suggests that the centre line arises from the O–CH2 carbon that is
in the proximity to the carbonyl ester of the acrylic backbone. In
the 30–45ppm region, two low intensity peaks are noticed at

670
G. S. M. Reddy et al.
42.62and 31.61 ppm and are assignedtothebackboneofmethine
as well as the methylene carbons. These peaks are contributed by
many lines arising from the stereochemically different monomer-
ic units in the polymeric chain. Two sharp peaks at 25.41 and
14.76ppm are assigned to the centre methylenesof the spacer and
the methyl carbons of the terminal chain, respectively. The FT-
IR, 1H NMR, and 13C NMR spectra unambiguously confirmed
the formation of polymer.
Since all the samples retain liquid crystalline textures even at
room temperature, identification of solidification was difficult
unlike for the low-molecular-weight liquid crystals. In order to
identify the fluidity, the coverslip was sheared at regular
intervals on cooling, and the sample mobility was observed.
To establish the enantiotropic nature of the mesophase, the
samples were reheated where mobility, typical of a liquid crystal
phase, was found at different temperatures for different poly-
mers. It is quite interesting to note that the smectic mesomorph-
ism dominated over the nematic phase. The appearance of the
SC phase in higher homologues is attributed to the lengthy
Polarising Optical Microscopy (POM)
The polymers synthesised were subjected to POM experiments in
order to find their mesophase characteristics and the results are
listed in Table 1. The results revealed that all the polymers were
enantiotropic. Oncoolingthesampleof4afromanisotropic melt,
its POM image exhibited a threaded texture, which is typical of a
nematic phase, and focal conic fans of a SA phase (Fig. 4). On
continuous cooling to room temperature, the fan texture was
retained. The immobility of the sample, when pressing the
coverslips, indicates the formation of a frozen liquid crystal glass,
which is a feature commonly observed in SCLCP.[20] In the case
of 4b, the next higher homologue of the series, a similar obser-
vation with varying temperatures was obtained. The POM
investigation of 4c, 4d, and 4e revealed the formation of a SC
phase (Fig. 4). However, a broken fan texture without homeo-
tropy was observed for 4c, whereas the texture consists of
schlieren and broken fans with homeotropic domains for 4d. In
the caseof4e, theobservationofa homogeneousschilerentexture
across the field confirmed the SC phase.
Table 1. Differential scanning calorimetry (DSC) and hot optical
polarising microscopy (HOPM) data of polymers
Tg, glass transition temperature; DH, change in enthalpy
Sample
code
Tg
Transitions
observed
by DSCA
Transition
DH
Phases
observed
by HOPMA
[8C]
temperatures [kJ molꢁ1
]
[8C]
4a
4b
4c
4d
4e
14
I–N, N–SA
I–N, I–SA
I–SC
108, 106
117, 80
104
16.94
N, SA
N, SA
SC
11
10
18
1.22, 0.73
3.98
I–SC
94
3.81
SC
32.0B I–SC
92
3.68
SC
AI: isotropic, N: nematic, SA: smectic A, SC: smectic C.
BThe melting temperature.
(b)
(a)
(c)
(d)
Fig. 4. The hot stage optical polarising microscopy photographs of (a) the focal conic fan texture of the smectic A (SA) phase of 4a at 1048C, (b) the SA
phase of 4b at 1228C, (c) the focal conic smectic C (SC) phase of 4c at 938C, and (d) the schilerene texture of the SC phase of 4d at 698C.

Thermotropic Side Chain Liquid Crystalline Polymers
671
4a
I–N
N–SA
SA–N
4a
N–I
I–N
N–SA
4b
SA–N
4b
N–I
4c
I–SC
4c
4d
I–SC
SC–I
4d
4e
SC–I
I–SC
4e
SC–I
Cr–SC
50
0
100
150
0
20
40
60
80
100
120
140
Temperature [ЊC]
Temperature [ЊC]
Fig. 5. Differential scanning calorimetry thermograms of polymers 4a–4e
on heating. I, isotropic; N, nematic; SA, smectic A; SC, smectic C; Cr,
crystallization.
Fig. 6. Differential scanning calorimetry thermograms of polymers 4a–4e
on cooling. I, isotropic; N, nematic; SA, smectic A; SC, smectic C; Cr,
crystallization.
terminal chain. The ester linking units of the polymers favour
the conjugation that enhances the molecular polarisability,
which contributes to lateral interactions rather than terminal
interactions, which are responsible for the smectic phase.
1.0
0.8
0.6
Differential Scanning Calorimetry (DSC) Studies
To corroborate the POM observations, the polymer samples were
subjectedtoDSCanalysis. Eachpolymersamplewassubjectedto
two heating and cooling cycles. The results obtained from the
second heating and cooling are considered for discussion. DSC
traces of the polymers are given in Fig. 5 and Fig. 6. Phase
transitions temperatures and the associated enthalpy values
determined from DSC are listed in Table 1. A good agreement
was noticed in terms of transition temperatures and the meso-
phases observed by hot stage optical polarising microscopy
(HOPM). For instance, the DSC thermogram of 4b showed two
transitions (at 808C and 1178C), which correspond to SA to
nematic and nematic to isotropic phases, respectively, whereas a
single broad peak at 1088C, due to the merging of two transitions,
which correspond to SA to nematic and nematic to isotropic
phases were observed for 4a. In the case of 4c, 4d, and 4e, only a
single transition was observed in the DSC for the SC phase. In
addition to the transitions that are related to mesophases, glass
transition phenomena were also observed for all the polymers
except 4e.
0.4
0.2
4c
4e
0
0
5
10
15
20
25
30
35
40
2θ
Fig. 7. X-Ray diffraction patterns of homopolymers at 808C (4c) and
858C (4e).
former was assigned to Tg, while the later was attributed to
isotropisation. Similarly, on cooling, isotropic to mesophase and
mesophase to glass transitions were observed.
Glass transition temperatures (Tgs) of the polymers were
found to be either lower or close to room temperature, due to the
presence of the spacer, thereby allowing the samples to appear to
be rubbery in nature. Generally, SCLCP exhibit two kinds of
transitions, i.e. glass to rubbery transitions (at the Tg) and
mesophase transitions.[9,21] The transition enthalpy associated
with mesophase transitions is high, since they are first order
thermodynamic transitions, whereas those associated with Tg
are too low to be identified because they are second-order
transitions. On heating, all the polymers showed typical sec-
ond-order transitions, followed by a first-order transition; the
Variable-Temperature X-Ray Diffraction (VT-XRD) Studies
The existence of a SC phase in the polymers was also confirmed
by using VT-XRD measurements. The X-ray diffraction profiles
measured at 808C for 4c and 858C for 4e are given in Fig. 7. The
figure shows the sharp and intense reflections at 2y ¼ 2.778 (4c)
and at 2y ¼ 2.888 (4e) in the small angle region and the broad
humps in the wide angle region. The appearance of sharp

672
G. S. M. Reddy et al.
reflections in the small angle region, which is typical for layer-
like ordering,[22–24] confirmed the SC phases in the polymers, as
observed by POM and DSC. The broad hump observed in the
wide angle region is due to the liquid-like order which arises
from the terminal octyl and dodecyl chains. The calculated
d-spacing values for the sharp reflections were found to be 30.0
values are listed in Table 3. Since monomers were polymerised
by a free radical addition mechanism, the PDI values were found
to be more than 1.5 for low-molecular-weight polymers. The
,Mw. of the polymers are in the range 6000–13000, whereas
the monomer weights are in the range of 400–550 g molꢁ1. Thus
the degree of polymerisation (DP) was found to be between 16
and 23. The lower homologue polymers showed low molecular
weights, while the higher homologue polymers, i.e. decyl and
dodecyl polymers (4d and 4e), showed a substantial increase in
their molecular weight. Similarly, the PD values also showed an
increasing tendency for decyl and dodecyl polymers.
˚
and 30.2 A, respectively, which suggest interdigitation of the
molecules in the smectic layers.
Thermogravimetric Analysis (TGA)
The thermal stability of all the polymers was determined by TGA
and TGA traces are given in Fig. 8. Accordingly, the initial and
final degradation temperatures (IDT and FDT) and decomposi-
tion temperature at 50 % weight loss were calculated and listed in
Table 2. The IDT for all the samples is around 3008C, while the
FDT are found to be in the range between 450 and 4958C. The
temperature at which 50 % weight loss of the polymers was found
to be ,4008C. These values suggest that the thermal stability of
the polymers is reasonably good.
Conclusions
In summary, a new series of polymers were synthesised in order
to establish their structure–property relationships. Although
some of the monomers failed to show liquid crystalline property,
all the polymers synthesised enantiotropically exhibited
nematic and smectic phases. The SC phase of the representative
samples was confirmed by XRD analysis. Disappearance of the
nematic and SA phases from the C8–C12 homologues and sta-
bilisation of the SC phase at C8 was observed along the series.
The introduction of an ester group between the spacer and core
reduced the isotropic temperatures and stabilised the SC phase
when compared with the ether analogues. In addition, increasing
the aspect ratio of the monomers increases the possibility of a
more ordered phase (SC). DSC and TGA analysis of the poly-
mers revealed their good thermal stability.
Molecular Weight Determination
All the polymers synthesised were analysed by gel permeation
chromatography (GPC) in order to determine the molecular
weight. The weight average molecular weight ,Mw., number
average molecular weight ,Mn., and polydispersity (PDI)
100
80
60
40
20
0
4a
4b
4c
4d
4e
Experimental
Materials
Benzyl-4-hydroxy benzoate, 4-ethoxy benzoic acid, 4-hexyloxy
benzoic acid, 4-octyloxy benzoic acid, 4-decyloxy benzoic acid,
4-dodecyloxy benzoicacid, 4-hydroxybutyl acrylate, palladium on
charcoal (Pd/C, 10 %), N,N0-dicyclohexylcarbodiimide (DCC),
and 4-dimethylaminopyridine (DMAP) were purchased from
Aldrich, USA and used without further purification. N,N0-Di-
methylformamide, tetrahydrofuran (THF), ethanol, and methanol
(SD Fine, Mumbai, India) were used as received. Dichloromethane
(DCM), methyl ethyl ketone (MEK), ethyl acetate, diethyl ether,
n-hexane, acetone, acetonitrile, isopropyl alcohol, potassium
hydroxide (pellets), Celite-540, anhydrous potassium carbonate,
anhydrous sodium sulphate, and silica gel (100–200 mesh) were
obtained from Merck-India, Mumbai and used as received.
Measurements
0
100
200
300
400
500
600
700
800
The FT-IR spectra of samples were recorded by the KBr pellet
method on a Thermo Mattson FT-IR spectrometer. 1H and 13
Temperature [ЊC]
C
NMR spectra of the compounds were recorded using a JEOL
ECA 500 NMR spectrometer; the samples were dissolved in
CDCl3 and TMS was used as an internal standard. The electron
Fig. 8. Thermogravimetric analysis curves of polymers 4a 4e.
]
Table 2. The initial and final degradation temperatures (IDT and
FDT) and decomposition temperature at 50 % weight loss (50 %) of the
polymers
Table 3. Molecular weights (g mole21) of the polymers
Sample
code
Weight-average
Number-average
Polydispersity
Sample code
IDT [8C]
50 % [8C]
FDT [8C]
molecular weight (Mw) molecular weight (Mn)
4a
4b
4c
4d
4e
303
321
326
311
293
391
398
413
403
395
478
457
488
495
456
4a
4b
4c
4d
4e
6861
6096
3666
3979
4661
5466
6840
1.87
1.53
1.53
2.01
1.92
7138
11004
13165

Thermotropic Side Chain Liquid Crystalline Polymers
673
impact (EI) mass spectra were recorded using a JEOL DX-303
spectrometer. Elemental analyses were recorded using an Ele-
mental Analyzer for CHNS, Model-Euro EA 3000, Euro Vector
S.P.A. The molecular weights of polymers were determined
using a WATERS GPC model BREEZE Million-3 fitted with a
DRI detector. THF was used as the mobile phase at a flow rate of
1 mL minꢁ1 at 308C. The weight-average molecular weights
were calculated from the calibration curve that was plotted using
linear polystyrene standards (1000–60000).
The mesophase behaviour and phase stability was investi-
gated using an Olympus BX50 POM equipped with a Linkam
THMS heating stage and TMS 94 temperature programmer with
a C 7070 digital camera. The samples were placed between two
12 mm coverslips and were heated with a programmed heating
rate. DSC scans were performed using a TA Instruments Q-10
series. The experiments were carried out in a nitrogen atmo-
sphere at a heating rate of 58C minꢁ1. Each sample was
subjected to two heating and cooling cycles and data obtained
from the second heating and cooling cycle were considered for
discussion. All the samples were crimpled in aluminium pans to
ensure good thermal contact between the sample and the pan.
TGA thermograms of the polymer samples were recorded on a
Q-10 series instrument in a nitrogen atmosphere at a heating rate
of 108C minꢁ1 in the temperature range of 30–8008C.
Small-angle X-ray scattering peaks were measured with an
evacuated high performance SAXS instrument ‘SAXSess’
(Anton Paar KG, Graz, Austria). The ‘SAXSess’ was attached
to a conventional X-ray generator (Philips, Holland) equipped
with a sealed X-ray tube (Cu anode target type, producing CuKa
X-rays with a wavelength of 0.154 nm), operating at 40 kV and
50 mA. The samples were measured using the paste cell method.
The scattered X-ray intensities were detected with a 2D-imaging
plate detection system Cyclone (Packard, A Packard Bioscience
Co.) with a spatial resolution of 50 ꢀ 50 mm2 per pixel at a
sample to detector distance of 265 mm. Scattering data read
from the imaging plate were first corrected for the absorption of
the X-rays in the sample and transformed to the q scale (q ¼ 4p/
l ꢂ sin y/2; program SAXS Quant; Anton Paar KG, Graz,
Austria). The SAXS measurements were further corrected with
the empty cell measurements.
4.12 (q, J 6.95, 2H, O–CH2), 1.46 (t, J 6.88, 3H, CH3). dC
(CDCl3) 165.84, 164.46, 163.65, 155.01, 136.08, 132.51,
131.40, 128.73, 128.39, 128.29, 127.62, 121.98, 121.16,
114.46, 66.90, 63.96, 14.77. m/z (EI) 376.4 (Mþ). Anal. Calc.
for C23H20O5: C 73.39, H 5.35. Found: C 73.12, H 5.21 %.
4-[(Benzyloxy)carbonyl]phenyl 4-Hexyloxybenzoate (1b)
Yield: 73 %, mp 69.28C, nmax (KBr)/cmꢁ1 3068 (aromatic
C–Hstr), 2944, 2868 (C–Hstr), 1722 (C¼Ostr), 1602 and 1506
(C¼Cstr aromatic), 1468 (C–Hben), 1261, 1202, and 1160 (C–O–
Casym & symstr of ester and ether, respectively). dH (CDCl3) 8.15
(t, J 8.93, 4H, Ar-H), 7.47 (d, J 7.30, 2H, Ar-H), 7.42 (t, J 7.25,
2H, Ar-H), 7.35 (t, J 7.20, 1H, Ar-H), 7.29 (d, J 8.45, 2H, Ar-H),
6.99 (d, J 8.78, 2H, Ar-H), 5.38 (s, 2H), 4.05 (t, J 6.29, 2H,
O–CH2), 1.82 (m, 2H, CH2), 1.49 (m, 2H, CH2), 1.36 (m, 4H,
CH2), 0.95 (t, J 6.68, 3H, CH3). dC (CDCl3) 165.82, 164.46,
163.88, 155.03, 136.11, 132.49, 131.40, 128.73, 128.39, 128.29,
127.62, 121.99, 121.11, 114.49, 68.47, 66.89, 31.66, 29.16,
25.77, 22.72, 14.17. m/z (EI) 432.5 (Mþ). Anal. Calc. for
C27H28O5: C 74.97, H 6.52. Found: C 74.42, H 6.24 %.
4-[(Benzyloxy)carbonyl]phenyl 4-Octyloxybenzoate (1c)
Yield: 73 %, mp 66.88C, nmax (KBr)/cmꢁ1 3068 (aromatic
C–Hstr), 2924, 2859 (C–Hstr), 1731 (C¼Ostr), 1604 and 1507
(C¼Cstr aromatic), 1473 (C–Hben), 1258, 1202, and 1162 (C–O–
Casym & symstr of ester and ether, respectively). dH (CDCl3) 8.14
(t, J 8.90, 4H, Ar-H), 7.44 (d, J 7.47, 2H, Ar-H), 7.39 (t, J 7.20,
2H, Ar-H), 7.33 (t, J 7.04, 1H, Ar-H), 7.28 (d, J 8.55, 2H, Ar-H),
6.96 (d, J 8.65, 2H, Ar-H), 5.39 (s, 2H), 4.02 (t, J 6.64, 2H,
O–CH2), 1.82 (m, 2H, CH2), 1.45 (m, 2H, CH2), 1.30 (m, 8H,
CH2), 0.88 (t, J 6.79, 3H, CH3). dC (CDCl3) 165.81, 164.44,
163.88, 155.04, 136.12, 132.49, 131.41, 128.73, 128.40, 128.28,
127.62, 121.99, 121.11, 114.49, 68.47, 66.89, 31.93, 29.46,
29.36, 29.21, 26.11, 22.79, 14.25. m/z (EI) 460.5 (Mþ). Anal.
Calc. for C29H32O5: C 75.62, H 7.00. Found: C 75.31, H 7.15 %.
4-[(Benzyloxy)carbonyl]phenyl 4-Decyloxybenzoate (1d)
Yield: 75 %, mp 688C, nmax (KBr)/cmꢁ1 3032 (aromatic C–Hstr),
2923, 2852 (C–Hstr), 1721 (C¼Ostr), 1604 and 1507 (C¼Cstr
aromatic), 1456 (C–Hben), 1264, 1208, and 1160 (C–O–Casym &
symstr of ester and ether, respectively). dH (CDCl3) 8.15 (t, J 9.17,
4H, Ar-H), 7.45 (d, 7.48, 2H, Ar-H), 7.40 (t, J 6.88, 2H, Ar-H),
7.34 (t, J 7.09, 1H, Ar-H), 7.29 (d, J 8.37, 2H, Ar-H), 6.97 (d, J
8.88, 2H, Ar-H), 5.37 (s, 2H), 4.04 (t, J 6.54, 2H, O–CH2), 1.82
(m, 2H, CH2), 1.48 (m, 2H, CH2), 1.34 (m, 12H, CH2), 0.88 (t, J
6.89, 3H, CH3). dC (CDCl3) 165.84, 164.47, 163.87, 155.01,
136.08, 132.48, 131.40, 128.72, 128.38, 128.28, 127.61, 121.98,
121.09, 114.49, 68.47, 66.89, 32.00, 29.66, 29.46, 29.42, 29.18,
26.07, 22.79, 14.23. m/z (EI) 488.6 (Mþ). Anal. Calc. for
C31H36O5: C 76.20, H 7.42. Found: C 76.44, H 7.21 %.
Synthesis of 4-[(Benzyloxy)carbonyl]phenyl
4-Ethoxybenzoate (1a)
In a representative experiment, 30.6 g (81 mmol) of 4-ethoxy
benzoic acid was placed in a 250 mL round bottom flask. To this,
14.27 g (250 mmol) of thionyl chloride was added and refluxed
for 1 h. The excess thionyl chloride was removed and the
product was dissolved with 150 mL of MEK and added dropwise
to a mixture of 22.8 g (100 mmol) of benzyl 4-hydroxybenzoate
and 18.36 g (120 mmol) of triethylamine in 300 mL of MEK at
08C over 1 h. The reaction mixture was then stirred for 3 h at
room temperature. The triethylamine salt obtained was filtered
off and the solvent was evaporated. The crystalline solid thus
obtained was washed with 5 % aqueous sodium hydroxide and
twice with distilled water. It was purified by recrystallising from
isopropyl alcohol.
Yield: 75 %, mp 109ꢁ1118C, nmax (KBr)/cmꢁ1 3069 (aro-
matic C–Hstr), 2978, 2935 (C–Hstr), 1726 (C¼Ostr), 1604 and
1506 (C¼Cstr aromatic), 1441 (C–Hben), 1276, 1255, 1214, and
1159 (C–O–Casym & symstr of ester and ether, respectively). dH
(CDCl3) 8.14 (t, J 8.39, 4H, Ar-H), 7.46 (d, J 7.05, 2H, Ar-H),
7.40 (t, J 7.04, 2H, Ar-H), 7.35 (t, J 6.71, 1H, Ar-H), 7.30
(d, J 8.79, 2H, Ar-H), 6.98 (d, J 9.12, 2H, Ar-H), 5.38 (s, 2H),
4-[(Benzyloxy)carbonyl]phenyl 4-Dodecyloxybenzoate (1e)
Yield: 75%, mp 678C, nmax (KBr)/cmꢁ1 3057 (aromatic C–Hstr),
2917, 2850 (C–Hstr), 1726 (C¼Ostr), 1604 and 1507 (C¼Cstr
aromatic), 1470 (C–Hben), 1290, 1253, 1214, and 1166 (C–O–
Casym & symstr of ester and ether, respectively). dH (CDCl3) 8.15
(t, J 9.13, 4H, Ar-H), 7.45 (d, J 7.66, 2H, Ar-H), 7.40 (t, J 7.19,
2H, Ar-H), 7.34 (t, J 7.05, 1H, Ar-H), 7.29 (d, J 8.41, 2H, Ar-H),
6.97 (d, J 8.59, 2H, Ar-H), 5.36 (s, 2H), 4.03 (t, J 6.92, 2H,
O–CH2), 1.82 (m, 2H, CH2), 1.48 (m, 2H, CH2), 1.31 (m, 16H,
CH2), 0.88 (t, J 6.75, 3H). dC (CDCl3) 165.82, 164.46, 163.87,
155.02, 136.09, 132.48, 131.40, 128.72, 128.38, 128.28, 127.61,

674
G. S. M. Reddy et al.
121.98, 121.10, 114.48, 68.46, 66.89, 32.02, 29.75, 29.70, 29.67,
29.47, 29.18, 26.08, 22.80, 14.25. m/z (EI) 516.6 (Mþ). Anal.
Calc. for C33H40O5: C 76.71, H 7.42. Found: 76.45, H 7.56%.
(d, J 9.07, 2H, Ar-H), 6.98 (d, J 9.04, 2H, Ar-H), 4.05 (t, J 6.39,
2H, O–CH2), 1.82 (m, 2H, CH2), 1.49 (m, 2H, CH2), 1.31 (m,
12H, CH2), 0.88 (t, J 6.38, 3H, O–CH2).dC (CDCl3) 168.90,
164.53, 163.83, 154.96, 132.46, 131.64, 127.87, 121.87, 121.08,
114.46, 68.44, 31.97, 29.63, 29.43, 29.37, 29.14, 26.04, 22.76,
14.22. m/z (EI) 399.4 ([M þ H]þ). Anal. Calc. for C24H30O5: C
72.33, H 7.58. Found: C 72.56, H 7.45 %.
Synthesis of 4-[(4-Ethoxybenzoyl)oxy] Benzoic Acid (2a)
In a typical experiment, 19.52 g (52.5 mmol) of 1a was placed in
a 500 mL three necked round bottom flask and 100 mL of THF
was added. A 1.9 g portion of 10 % Pd/C was added to the
solution and it was purged with hydrogen gas at room temper-
ature for 48 h in order to obtain the acid.[25,26] The Pd/C catalyst
was then removed by filtering the reaction mixture through
Celite-540 and upon evaporation of the solvent yielded the white
solid which was recrystallised from propan-1-ol.
Yield: 90 %, mp nematic, 227–2738C, nmax (KBr)/cmꢁ1 3049
(aromatic C–Hstr), 2996, 2946 (C–Hstr), 2668, 2549 (O–Hstr of
carboxylic acid) 1746 (C¼Ostr), 1685 (C¼Ostr of carboxylic
acid), 1603 and 1510 (C¼Cstr aromatic), 1425 (C–Hben), 1260,
1211, and 1158 (C–O–Casym & symstr of ester and ether, respec-
tively). dH (acetone-d6) 8.10 (d, J 8.49, 4H, Ar-H), 7.40 (d, J
8.92, 2H, Ar-H), 7.09 (d, J 9.13, 2H, Ar-H), 4.17 (q, J 6.80, 2H,
O–CH2), 1.39 (t, J 6.9, 3H, CH3). dC (acetone-d6) 165.90,
163.94, 163.78, 155.07, 132.24, 131.16, 128.01, 122.18,
121.18, 114.56, 63.84, 13.47. m/z (EI) 286.2 (Mþ). Anal. Calc.
for C16H20O5: C 67.12, H 4.92. Found: C 67.03, H 5.01 %.
4-[(4-Dodecyloxybenzoyl)oxy] Benzoic Acid (2e)
Yield: 90%, mp nematic, smectic, 125–2238C, nmax (KBr)/cmꢁ1
3073 (aromatic C–Hstr), 2922, 2851 (C–Hstr), 2670, 2549 (O–Hstr
of carboxylic acid) 1733 (C¼Ostr), 1689 (C¼Ostr of carboxylic
acid), 1603 and 1510 (C¼Cstr aromatic), 1468 (C–Hben), 1261,
1214, and 1163 (C–O–Casym & symstr of ester and ether, respec-
tively). dH (CDCl3) 8.20 (d, J 8.87, 2H, Ar-H), 8.15 (d, J 8.43, 2H,
Ar-H), 7.34 (d, J 8.87, 2H, Ar-H), 6.99 (d, J 8.97, 2H, Ar-H), 4.06
(t, J 6.55, 2H, O–CH2), 1.82 (m, 2H, CH2), 1.47 (m, 2H, CH2),
1.35(m, 17H, CH2), 0.88(t, J 6.52, 3H, CH3). dC (CDCl3) 170.92,
164.43, 163.89, 155.61, 132.51, 131.97, 126.76, 122.15, 121.01,
114.46, 68.46, 32.01, 29.75, 29.73, 29.68, 29.65, 29.45, 29.16,
26.06, 22.79, 14.23. m/z (EI) 426.5 (Mþ). Anal. Calc. for
C26H34O5: C 73.21, H 8.03. Found: C 73.09, H 7.93%.
Synthesis of Monomers
4-[(Acryloyloxybutoxy)carbonyl]phenyl
4-Ethoxybenzoate (3a)
4-[(4-Hexyloxybenzoyl)oxy] Benzoic Acid (2b)
Yield: 90 %, mp nematic, 169–2458C, nmax (KBr)/cmꢁ1 3073
(aromatic C–Hstr), 2936, 2864 (C–Hstr), 2664, 2546 (O–Hstr of
carboxylic acid) 1739 (C¼Ostr), 1686 (C¼Ostr of carboxylic
acid), 1603 and 1509 (C¼Cstr aromatic), 1470 (C–Hben), 1250,
1208, and 1162 (C–O–Casym & symstr of ester and ether, respec-
tively). dH (acetone-d6) 8.12 (d, J 8.88, 2H, Ar-H), 8.10 (d, J
9.17, 2H, Ar-H), 7.40 (d, J 8.14, 2H, Ar-H), 7.10 (d, J 9.05, 2H,
Ar-H), 4.11 (t, J 6.84, 2H, O-CH2), 1.79 (m, 2H, CH2), 1.49 (m,
2H, CH2), 1.33 (m, 4H, CH2), 0.88 (t, J 6.89, 3H, CH3). dC
(acetone-d6) 166.07, 163.95, 155.07, 132.23, 131.17, 128.01,
122.17, 121.16, 114.60, 68.27, 31.46, 25.54, 22.45, 13.47. m/z
(EI) 342.3 (Mþ). Anal. Calc. for C20H22O5: C 70.15, H 7.91, N
6.47. Found: C 70.01, H 6.23 %.
In a typical experiment, 7.15 g (25 mmol) of 4-[(4-
ethoxybenzoyl)oxy] benzoic acid and 3.6 g (25 mmol) of
4-hydroxybutylacrylate were placed in a conical flask and
dissolved in 100 mL of THF. To this stirred solution, 6.18 g
(30 mmol) of DCC dissolved in 50 mL of DCM was added,
followed by the addition of DMAP (2.5 mmol) and stirring was
continued overnight at room temperature. Filtration of solid
dicyclohexyl urea and subsequent evaporation of the solvent
yielded a semi solid which was purified by column chromato-
graphy using a 1 : 4 mixture of ethyl acetate and hexane as eluent
in order to obtain a white solid.
Yield: 60 %, nmax (KBr)/cmꢁ1 3075 (aromatic C–Hstr), 2979,
2958 (C–Hstr), 1722 (C¼Ostr), 1634 (C¼Cstr) 1603, 1578, 1509
(C¼Cstr aromatic), 1473 (C–Hben), 1260, 1203, and 1164 (C–O–
Casym & symstr of ester and ether, respectively). dH (CDCl3) 8.12
(d, J 8.79, 2H, Ar-H), 8.10 (d, J 8.53, 2H) 7.26 (d, J 8.45, 2H, Ar-
H), 6.95 (d, J 8.92, 2H, Ar-H), 6.41 (d, J 16.4, 1H), 6.11 (dd, J
10.1 1H), 5.82 (d, J 10.5, 1H), 4.37, (t, J 5.95, 2H), 4.18 (t, J 5.99
2H), 4.10 (m, 2H), 1.85 (br s, 4H), 1.43 (q, 3H). dC (CDCl3)
166.31, 165.93, 164.46, 163.64, 154.91, 132.47, 131.21130.88,
128.49, 127.72, 121.94, 121.15, 114.45, 64.62, 64.11, 63.94,
25.55, 25.49, 14.73. m/z (EI) 412.4 (Mþ). Anal. Calc. for
C23H24O7: C 66.97 H 5.86. Found: C 66.85, H 5.72 %.
4-[(4-Octyloxybenzoyl)oxy] Benzoic Acid (2c)
Yield: 90 %, mp nematic, smectic, 147–2398C, nmax (KBr)/cmꢁ1
3079 (aromatic C–Hstr), 2922, 2853 (C–Hstr), 2653, 2534
(O–Hstr of carboxylic acid) 1734 (C¼Ostr), 1683 (C¼Ostr of
carboxylic acid), 1600 and 1508 (C¼Cstr aromatic), 1470
(C–Hben), 1253, 1208, and 1161 (C–O–Casym & symstr of ester and
ether, respectively). dH (CDCl3) 8.20 (d, J 8.39, 2H, Ar-H), 8.15
(d, J 8.67, 2H, Ar-H), 7.34 (d, J 8.43, 2H, Ar-H), 6.99 (d, J 9.05,
2H, Ar-H), 4.05 (t, J 6.16, 2H, O–CH2), 1.82 (m, 2H, CH2), 1.48
(m, 2H, CH2), 1.32 (m, 8H, CH2), 0.88 (t, J 6.93, 3H, CH3). dC
(CDCl3) 165.9, 164.46, 163.90, 155.61, 132.52, 132.00, 126.72,
122.12, 120.99, 114.49, 68.48, 31.95, 29.43, 29.34, 29.17,
26.08, 22.76, 14.23. m/z (EI) 370.4 (Mþ). Anal. Calc. for
C22H26O5: C 71.33, H 7.07. Found: C 71.05, H 7.19 %.
4-[(Acryloyloxybutoxy)carbonyl]phenyl
4-Hexyloxybenzoate (3b)
Yield: 60 %, nmax (KBr)/cmꢁ1 2952, 2865 (C–Hstr), 1726
(C¼Ostr), 1636 (C¼Cstr), 1604, 1509 (C¼Cstr aromatic), 1464
(C–Hben), 1262, 1202, and 1164 (C–O–Casym & symstr of ester and
ether, respectively). dH (CDCl3) 8.09 (m, 4H), 7.26 (d, J 8.5,
2H), 6.94 (d, J 8.7, 2H), 6.39 (d, J 16.78, 1H), 6.10 (dd, J 9.99,
1H), 5.79 (d, J 11.53, 1H), 4.34, (t, 2H), 4.21 (t, 2H), 3.99 (t, 2H),
1.77 (m, 6H), 1.43 (m, 2H), 1.31 (m, 4H), 0.88 (t, 3H). dC
(CDCl3) 166.23, 165.86, 164.39, 163.84, 154.91, 132.43,
131.19, 130.83, 128.49, 127.69, 121.93, 121.05, 114.45,
68.40, 64.58, 64.08, 31.61, 29.11, 25.72, 25.53, 25.47, 22.66,
4-[(4-Decyloxybenzoyl)oxy] Benzoic Acid (2d)
Yield: 90 %, mp nematic, smectic, 132–2338C, nmax (KBr)/cmꢁ1
3073 (aromatic C–Hstr), 2921, 2853 (C–Hstr), 2670, 2552
(O–Hstr of carboxylic acid) 1736 (C¼Ostr), 1690 (C¼Ostr of
carboxylic acid), 1603 and 1510 (C¼Cstr aromatic), 1425
(C–Hben), 1260, 1205, and 1163 (C–O–Casym & symstr of ester and
ether, respectively). dH (CDCl3) 8.14 (m, J 8.05, 4H, Ar-H), 7.30

Thermotropic Side Chain Liquid Crystalline Polymers
675
14.11. m/z (EI) 468.5 (Mþ). Anal. Calc. for C27H32O7: C 69.21,
H 6.88. Found: C 68.95, H 7.01 %.
methanol. The white polymer solid obtained was further purified
by redissolving it in chloroform and precipitating it in methanol.
Yield: 72 %.
4-[(Acryloyloxybutoxy)carbonyl]phenyl
4-Octyloxybenzoate (3c)
Acknowledgements
Yield: 60 %, mp 498C, nmax (KBr)/cmꢁ1 2929, 2857 (C–Hstr),
1728 (C¼Ostr), 1636 (C¼C), 1605, 1510 (C¼Cstr aromatic),
1468 (C–Hben), 1263, 1202, and 1163 (C–O–Casym & symstr of
ester and ether, respectively). dH (CDCl3) 8.13 (d, J 8.50, 2H),
8.09 (d, J 8.36, 2H) 7.27 (d, J 9.16, 2H), 6.95 (d, J 8.45, 2H), 6.38
(dd, J 16.83, 1H), 6.12 (dd, J 10.72, 1H), 5.82 (dd, J 9.64, 1H),
4.37, (t, J 6.1, 2H), 4.23 (t, J 6.44, 2H), 4.03 (t, J 6.15, 2H), 1.86
(m, 6H), 1.44 (m, 2H), 1.30 (m, 8H), 0.88 (t, J 6.47, 3H). dH
(CDCl3) 166.29, 165.92, 164.46, 163.85, 154.93, 132.46,
131.22, 130.86, 128.50, 127.72, 121.95, 121.08, 114.46,
68.45, 64.61, 64.11, 31.88, 29.41, 29.31, 29.16, 26.06, 25.56,
25.50, 22.74, 14.20. m/z (EI) 496.5 (Mþ). Anal. Calc. for
C29H36O7: C 70.14, H 7.30. Found: C 70. 37, H 7.18 %.
One of the authors (GSMR) sincerely thanks Dr A. B. Mandal, Director,
CLRI for his support in allowing the work to be carried out at the CLRI,
Polymer Division. He also wishes to thank the Tshwane University of
Technology for financial support, in the form of a postdoctoral fellowship.
References
[1] X. Wang, Q. Zhou, Liquid Crystalline Polymers 2004 (World Scien-
tific Publishing Co.: Singapore).
[2] S. Poser, H. Fisher, M. Arnold, Prog. Polym. Sci. 1998, 23, 1337.
doi:10.1016/S0079-6700(97)00051-8
[3] W. Kreuder, O. W. Webster, H. Ringsdorf, Makromol. Chem., Rapid.
Commun. 1986, 7, 5. doi:10.1002/MARC.1986.030070102
[4] H. Finkelmann, H. Ringsdorf, J. H. Wendorf, Makromol. Chem. 1978,
179, 273. doi:10.1002/MACP.1978.021790129
[5] H. Finkelmann, Polymer Liquid Crystals 1982 (Academic Press: New
4-[(Acryloyloxybutoxy)carbonyl]phenyl
4-Decyloxybenzoate (3d)
York, NY).
[6] N. A. Plate´, V. P. Shibaev, Makromol. Chem. Suppl. 1984, 6, 3.
doi:10.1002/MACP.1984.020061984101
[7] V. P. Shibaev, N. A. Plate, Pure Appl. Chem. 1985, 57, 1589.
doi:10.1351/PAC198557111589
[8] C. Noe¨l, P. Navarad, Prog. Polym. Sci. 1991, 16, 55. doi:10.1016/
0079-6700(91)90007-8
[9] H. A. Jacobs, G. M. Day, W. R. Jackson, G. P. Simmon, K. G. Watson,
S. Zheng, Aust. J. Chem. 1992, 45, 695. doi:10.1071/CH9920695
[10] M. Portugall, H. Ringsdorf, R. Zentel, Makromol. Chem. 1982, 183,
2311. doi:10.1002/MACP.1982.021831003
Yield: 60 %, mp 428C, nmax (KBr)/cmꢁ1 2924, 2853 (C–Hstr),
1726 (C¼Ostr), 1636 (C¼Cstr), 1606, 1510 (C¼Cstr aromatic),
1469 (C–Hben), 1274 and 1167 (C–O–Cstr of ester and ether,
respectively). dH (CDCl3) 8.13 (d, J 9.1, 2H, Ar-H), 8.11 (d, J
9.17, 2H, Ar-H) 7.27 (d, J 8.41, 2H, Ar-H), 6.95 (d, J 9.15, 2H,
Ar-H), 6.42 (dd, J 16.08, 1H), 6.14 (dd, J 9.91, 1H), 5.81 (dd, J
9.21, 1H), 4.36, (t, J 5.72, 2H), 4.23 (t, J 6.14, 2H), 4.03 (t, J 6.36,
2H), 1.85 (m, 6H), 1.48 (m, 2H), 1.34 (m, 12H), 0.87 (t, J 6.52,
3H). dC (CDCl3) 166.30, 165.94, 164.47, 163.85, 154.92,
132.46, 131.22, 130.88, 128.50, 127.72, 121.95, 121.08,
114.46, 68.45, 64.62, 64.12, 31.98, 29.64, 29.45, 29.40, 29.16,
26.06, 25.56, 25.50, 22.77, 14.22. m/z (EI) 524.6 (Mþ). Anal.
Calc. for C31H40O7: C 70.96, H 7.68. Found: C 71.05, H 7.59 %.
[11] Y. B. Amerik, B. A. Krentsel, J. Polym. Sci., Part C: Polym. Symp.
1967, 16, 1383. doi:10.1002/POLC.5070160316
[12] F. M. Hermay, Encyclopedia of Polymers and Engineering, 2nd edn,
Vol. 9 1987 (John Wiley & Sons: New York, NY).
[13] Y. K. Godovsky, V. S. Papkov, Adv. Polym. Sci. 1989, 88, 129.
doi:10.1007/BFB0017966
[14] E. Perplies, H. Ringsdorf, J. H. Wendorff, Makromol. Chem. 1974,
4-[(Acryloyloxybutoxy)carbonyl]phenyl
4-Dodecyloxybenzoate (3e)
175, 553. doi:10.1002/MACP.1974.021750217
[15] V. N. Tsvetkov, E. I. Riumtsev, I. N. Shetennikova, E. V. Korneeva,
B. A. Krenstel, A. Turner-Jones, Eur. Polym. J. 1973, 9, 481.
doi:10.1016/0014-3057(73)90031-1
[16] I. A. Borthwick, J. M. W. Cowie, Polym. Adv. Technol. 1998, 9, 128.
doi:10.1002/(SICI)1099-1581(199802)9: 2,128::AID-PAT741.3.0.
CO;2-8
[17] J. H. Liu, P. C. Yang, Y. H. Chiu, Y. Suda, J. Polym. Sci., Part A:
Polym. Chem. 2007, 45, 2026. doi:10.1002/POLA.21968
[18] R. Lorenz, Liq. Cryst. 1989, 6, 667. doi:10.1080/02678298908029109
[19] R. Lorenz, Liq. Cryst. 1991, 9, 127. doi:10.1080/02678299108036771
[20] A. Shanavas, T. Narasimhaswamy, A. S. Nasar, Aust. J. Chem. 2012,
65, 1426. doi:10.1071/CH12258
[21] F. V. Pereira, R. Borsali, O. M. S. Ritter, P. F. Gonc¸alves, A. A. Merlo,
N. P. da Silveira, J. Braz. Chem. Soc. 2006, 17, 333. doi:10.1590/
S0103-50532006000200017
Yield: 60 %, mp 578C, nmax (KBr)/cmꢁ1 2921, 2852 (C–Hstr),
1723 (C¼Ostr), 1634 (C¼Cstr), 1607, 1510 (C¼Cstr aromatic),
1470 (C–Hben), 1278, 1208, and 1168 (C–O–Cstr of ester and
ether, respectively). dH (CDCl3) 8.13 (d, J 8.95, 2H, Ar-H), 8.10
(d, J 8.70, 2H, Ar-H), 7.28 (d, J 9.08, 2H, Ar-H), 6.97 (d, J 9.10,
2H, Ar-H), 6.38 (dd, J 16.07, 1H), 6.11 (dd, J 9.98, 1H), 5.81 (dd,
J 9.81 1H), 4.37, (t, J 5.91, 2H), 4.23 (t, J 6.02, 2H), 4.03 (t, J
6.42, 2H), 1.82 (m, 6H), 1.46 (m, 2H), 1.33 (m, 16H), 0.87 (t, J
6.65, 3H). dC (CDCl3) 166.29, 165.93, 164.46, 163.85, 154.93,
132.45, 131.21, 130.85, 128.50, 127.72, 121.94, 121.09, 114.46,
68.45, 64.61, 64.11, 32.00, 29.74, 29.72, 29.67, 29.64, 29.44,
29.16, 26.05, 25.56, 25.50, 22.77, 14.21. m/z (EI) 553.7
([M þ H]þ). Anal. Calc. for C33H44O7: C 71.71, H 8.02. Found:
C 71.89, H 7.92 %.
[22] A. De Vries, Mol. Cryst. Liq. Cryst. 1985, 131, 125. doi:10.1080/
00268948508084198
[23] J. Frenzel, G. Rehage, Makromol. Chem. 1983, 184, 1685.
doi:10.1002/MACP.1983.021840814
[24] P. J. Kocienski, Protecting Groups, 3rd edn 2005 (Georg Thieme:
Preparation of Polymers
In a typical experiment, 1 g of 2a was placed in a polymerisation
tube and 1,4-dioxane (30 mL) and 0.01 g of benzoyl peroxide
were added. The solution was flushed with nitrogen gas for a few
minutes, tightly closed, and kept in a thermostated water bath at
70 ꢃ 18C. The polymerisation was continued for 24 h, and the
viscous polymer thus formed was precipitated by pouring into
Stuttgart).
[25] W. Greene, Protecting Groups in Organic Synthesis 2007 (John Wiley
& Sons: New York, NY).
[26] K. E. Rowe, D. W. Bruce, J. Mater. Chem. 1998, 8, 331. doi:10.1039/
A706400D