in a N-methylpyrrolidone (NMP)–LiCl–pyridine solution with
triphenylphosphite. A DSC trace of this polyamide was very
similar to that of the polyester analogue, exhibiting an exother-
mic peak at ca. 300 °C and an endothermic trough at 180 °C.
The solution behaviour of this polyamide was investigated in
water, DMSO and a 151 mixture of DMSO and water. The
results are summarised in Table 5.
It can be seen from the above data that this polyamide does
indeed exhibit lyotropic LC phases in appropriate solvents.
Although 10 is insoluble in water itself, it is very soluble in
spectrometer. In IR data, str=stretch. Microanalytical data
were obtained from the Microanalytical Service in the
Department of Pure and Applied Chemistry of the University
of Strathclyde. Optical studies were performed on an Olympus
Polarising Microscope. Differential scanning calorimery stud-
ies were carried out on a Du Pont Instruments 910 DSC.
Capillary viscosity measurements were made in an Ubbelohde
viscometer in an equilibrated water-bath at 30 °C. Statistical
light scattering measurements were performed at ICI Films,
Wilton. Glassware was silanised by rinsing with a 3% silicone
oil in methyl ethyl ketone solution, decanting the liquid and
placing in a furnace at 400 °C for 4 h.
151 DMSO–H O and shows a lyotropic LC phase above ca.
50 mass%. Similarly, in DMSO, a lyotropic LC phase is seen
2
above a concentration of ca. 45 mass%. This polyamide was
not found to be soluble in any other common organic solvents.
These results can be compared to the published data on the
analogous poly(p-phenylene nitroterephthalamide).9 This
polymer is insoluble in water at room temperature and dis-
solves only at ca. 100 °C over a period of time. Aqueous
polymer solutions with concentrations of 0.4–0.7 mass% are
reported to be birefringent when sheared. Such a low concen-
tration solution showing birefringence was questioned by the
authors as being indicative of liquid crystallinity, and is
certainly markedly different from the concentrations of ca.
45–50 mass% required for polyamide 10 to show anisotropic
behaviour in aqueous and pure DMSO.
Synthesis of monomers
2-Methoxy-5-nitroterephthalic acid10 and 2-bromo-5-nitro-
terephthalic acid.11 These were prepared as described in the
literature. The acid chlorides were prepared by refluxing the
appropriate diacid compound in thionyl chloride and purified
by micro-distillation including 2-bromoterephthaloyl chloride
and 2-nitroterephthaloyl chloride which were prepared as pre-
viously described.3
2-Methoxyterephthalic acid. A mixture of 2,5-dimethylanisole
(3.0 g, 22.03 mmol), potassium permanganate (12.0 g,
75.93 mmol) and distilled water (300 ml) was refluxed for 5 h.
The mixture was cooled to room temp. and poured into stirred
cold ethanol (200 ml). This mixture was then filtered, washed
thoroughly with water, reduced under vacuum, and acidified
with conc. hydrochloric acid. The resulting white precipitate
was collected by filtration, washed with water and dried (2.26 g,
52.3%), mp 287–288 °C (lit., 280 °C12 or 296–297 °C13) [Found:
C, 54.8; H, 4.0. C H O (196.16) requires C, 55.1; H, 4.1%];
Conclusions
Three novel homopolyesters formed from the interfacial reac-
tion of hydroquinonesulfonic acid and various diacid chlorides
are reported. Of these, the polyester 5 bearing a nitro and
methoxy function on the diacid unit exhibits lyotropicity in
151 DMSO–H O, DMSO and DMF. Two series of copoly-
esters are reported which contain increasing amounts of unsub-
9
8 5
2
u
/cm−1 (KBr) 1703 (CNO str); d ([2H ]DMSO) 3.87 (3H,
max
s, OCH ), 7.55 (2H, br d, J 8, 5,6-H), 7.68 (1H, d, J 8, 3-
5,6 3,5
H
6
stituted and bromo-substituted diacid units. It was found that
the fully nitro polyester 1 could incorporate up to 50% of the
non-mesogenic diacid and retain the ability to form lyotropic
mesophases. A series of copolyesters containing increasing
amounts of nitroisophthaloyl units is also reported. It was
found that the overall composition of the copolymer could
contain no more than ca. 9% of the meta-arranged diacid and
retain the ability to form fully orientated mesophases.
Furthermore, as the nitroisophthaloyl content increased the
copolymer became more insoluble in aqueous organic solvents.
Finally, poly(sulfo-p-phenylene nitroterephthalamide) 10 has
been prepared and shown to form a lyotropic LC phase in
DMSO and aqueous DMSO.
3
H), 13.15 (2H, br s, 2× CO H); d ([2H ]DMSO) 55.82
2
C
6
(OCH ), 112.51 (3-C), 121.00 (5-C), 125.72 (1-C), 130.33 (6-
C), 134.52 (4-C), 157.51 (2-C), 166.60 and 167.00 (both CO H).
3
2
2-Methoxyterephthaloyl chloride.14 (100%), mp 51–52 °C
[Found : C, 46.2; H, 2.6; Cl, 30.6. C H Cl O (233.05) requires
9
6 2 3
C, 46.4; H, 2.6; Cl, 30.4%]; u /cm−1 (CNO str); d (CDCl )
max
4.02 (3H, s, OCH ), 7.67 (1H, d, J 2, 3-H), 7.81 (1H, dd,
3,5
2, J 8, 5-H), 8.09 (1H, d, J 8, 6-H); d (CDCl ) 56.8
H
3
3
J
5,3
5,6
6,5
C
3
(OCH ), 114.0 (3-C), 123.1 (1-C), 128.8 (5-C), 133.5 (6-C),
138.8 (4-C), 158.7 (2-C), 164.1 and 167.7 (both COCl).
3
2-Bromo-5-nitroterephthaloyl
chloride.
(95.0%),
mp
53–55 °C, bp 135–140 °C at 0.02 mbar [Found: C, 29.55; H,
0.8; N, 4.0; Cl, 21.9; Br, 23.7. C H NO BrCl (326.92) requires
Experimental
8
2
4
2
C, 29.4; H, 0.6; N, 4.3; Cl, 21.7; Br, 24.0%]; u /cm−1 (CHCl )
Ethanol-free chloroform was prepared by elution through silica
and subsequent distillation. Other solvents were used as
received. Solid chemicals were supplied by Aldrich Chemical
Co. and used as recieved except for hydroquinonesulfonic acid
potassium salt, which was recrystallised from distilled water.
1H NMR spectra were recorded at 250 MHz on a Bruker
AMX-250 spectrometer. J Values are in Hz. Fourier transform
infrared spectra were obtained on a Nicolet Impact 400D
max
3
3030s (CMH arom str), 1778br (C=O str), 1540 (NMO anti
str), 1350 (NMO symm str); d (CDCl ) 7.99 (1H, s), 8.74 (1H,
s); d (CDCl ) 128.15 (6-C), 128.27 (2-C), 133.97 (4-C), 135.97
H
3
C
3
(3-C), 138.57 (1-C), 143.11 (5-C), 163.64 and 164.06 (both
COCl).
2-Methoxy-5-nitroterephthaloyl chloride. (76.1%), bp 175–
180 °C at 0.03 mbar [Found: C, 38.8; H, 1.9; N, 5.15; Cl, 25.45.
C H NO Cl (278.05) requires C, 38.9; H, 1.8; N, 5.0; Cl,
9
5
5 2
Table 5 Solution properties of poly(sulfo-p-phenylene nitroterephthal-
amide) (10)
25.5%]; u /cm−1 (CHCl ) 1786br (CNO str); d (CDCl )
max
4.13 (3H, s, OCH ), 7.10 (1H, s, 3-H), 8.89 (1H, s, 6-H); d
3
H
3
C
3
(CDCl ) 57.96 (OCH ), 110.69 (3-C), 130.86 (1-C), 136.05 (4-
C), 139.30 (5-C), 162.11 (2-C), 162.92 and 164.95 (both CO H).
solvent
concentrationa
observationb
insoluble
nematic solution
isotropic solution
nematic solution
3
3
2
H O
2
<10
45
40
50
DMSO
5-Nitroisophthaloyl chloride. (97.2%), bp 145–150 °C at
0.06 mbar (lit.,15 mp 67–68 °C) [Found: C, 39.3; H, 1.3; N, 5.1;
Cl, 28.6. C H NO Cl (248.02) requires C, 38.7; H, 1.2; N, 5.65;
151 DMSO–H O
2
8
3
4 2
Cl, 28.6%]; u /cm−1 (CHCl ) 3095, 1761s (CNO str), 1632,
max
1363, 1260, 1157; d (CDCl ) 9.12 (1H, t, J and J 2, 2-H),
2,4 2,6
aExpressed as mass% polymer to the nearest integer. bUnder cross-
polarised light.
3
H
3
1990
J. Mater. Chem., 1997, 7(10), 1985–1991