New fluorinated aromatic poly(ether-amide)s derived from 2,2′-bis(3,4,5-trifluorophenyl)-4,4′-diaminodiphenyl ether and various dicarboxylic acids

Article abstract of DOI:10.1016/j.jfluchem.2011.02.004

A new class of highly fluorinated aromatic poly(ether-amide)s was prepared through triphenyl phosphite-activated polycondensation of 2,2′-bis(3,4,5- trifluorophenyl)-4,4′-diaminodiphenyl ether (FPAPE) and four dicarboxylic acid comonomers. All the resulti

Full text of DOI:10.1016/j.jfluchem.2011.02.004

Journal of Fluorine Chemistry 132 (2011) 276–284
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Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
New fluorinated aromatic poly(ether-amide)s derived from 2,20-bis
(3,4,5-trifluorophenyl)-4,40-diaminodiphenyl ether and various dicarboxylic acids
*
Hossein Behniafar , Mohsen Sedaghatdoost
School of Chemistry, Damghan University, 36715-364, Damghan, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
A new class of highly fluorinated aromatic poly(ether-amide)s was prepared through triphenyl
phosphite-activated polycondensation of 2,20-bis(3,4,5-trifluorophenyl)-4,40-diaminodiphenyl ether
(FPAPE) and four dicarboxylic acid comonomers. All the resulting polymers were thoroughly
characterized by FT-IR, UV, and NMR spectroscopic methods. The effects of the fluorine atoms directly
linked to the lateral phenyl rings as well as fluoro-containing phenyl groups attached to the
macromolecular chains on some properties of the polymers were investigated by comparing with
poly(ether-amide)s prepared from 4,40-oxydianiline (4,40-ODA) and 2,20-diphenyl-4,40-diaminodiphenyl
ether (PAPE). The FPAPE-derived polymers exhibited excellent solubility in a variety of organic solvents.
Results obtained from X-ray studies showed that the presence of the bulky fluoro-containing phenyl
groups attached to the chains disrupts their structural order in a great amount, and leads to a decrease in
crystallinity extent of the macromolecules. Furthermore, the highly fluorinated polymeric chains
showed a significant enhancement in organo-solubility, heat-stability and Tg values when compared to
their non-fluorinated counterparts.
Received 6 January 2011
Received in revised form 28 January 2011
Accepted 2 February 2011
Available online 5 March 2011
Keywords:
Poly(ether-amide)s
Solubility
Crystallinity
Thermally stable polymers
ß 2011 Elsevier B.V. All rights reserved.
1. Introduction
procedures to achieve a good compromise in the desired
properties [17–23]. Fluoro-containing substituents, including
fluorine atoms or fluoroalkyl groups such as CF3 possess large
electronegativities and, thus, often endow fluoropolymers with
good organo-solubility. Meanwhile, the thermal properties of
the polymers can often be maintained because of the outstand-
ing thermal and thermooxidative stability of the fluoro groups
[24]. Compared with those aromatic polymers having –CF3
groups attached to the macromolecular backbone, polymers
possessing directly linked fluorine atoms to the aromatic main
chain [25–28] exhibit much lower molar volume, and this class
of polyfluorinated aromatic polyamides has been proposed to be
used as coatings for optical waveguide fabrication [29].
In our previous study we successfully prepared a highly
fluorinated aromatic diamine monomer namely 2,20-bis(3,4,5-
trifluorophenyl)-4,40-diaminodiphenyl ether (FPAPE) via a two-
step pathway starting from 2,20-diiodo-4,40-dinitrodiphenyl
ether (DINPE) [30]. It is noticeable that the mentioned two-
step pathway has been also utilized formerly to synthesize a
diamine structurally similar to FPAPE by the name of 2,20-bis(p-
phenoxyphenyl)-4,40-diaminodiphenyl ether (PPAPE), which
was used to prepare the corresponding aromatic polyimides
[31] and polyamides [32]. FPAPE has six fluorine atoms directly
attached to the lateral phenyl rings instead of two p-phenoxy
groups in the structure of PPAPE.
Aromatic polyamides are one of the most important classes
of high-performance polymers. This family of materials along
with aromatic polyimides plays
a vital role in advanced
technologies. For practical use in various recent applications,
new aromatic polyamides possessing both high thermal stability
and solubility in common organic solvents are required [1,2]. To
obtain different properties and for different applications, various
structural changes have been introduced in aromatic polyamide
backbones [3–12]. Introduction of bulky substituents into the
macromolecular chains is expected to decrease their orderly
arrangement. With this kind of structural modification an
enhanced organo-solubility and reduced chain crystallinity are
subsequently resulted [13–16]. In recent years, however,
considerable attention has been devoted to the fluorinated
aromatic polyamides. Fluoro-containing aromatic polyamides
have attracted much attention due to their outstanding
properties. This class of engineering plastics exhibits highly
thermal stability and chemical inertness. Among the modifica-
tions, fluorination might be one of the most promising
* Corresponding author. Tel.: +98 232 5235431; fax: +98 232 5235431.
E-mail address: h_behniafar@du.ac.ir (H. Behniafar).
0022-1139/$ – see front matter ß 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2011.02.004

H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
277
frompolycondensationofPAPEandpyromelliticdianhydride(PAPE/
PDA) is discussed in a continuation to compare its characteristics
with poly(ether-amide)s prepared here. In addition to PAPE/PDA, to
investigate the effect of lateral group nature, a previously reported
poly(ether-amide) having phenoxy groups attached to the lateral
phenyl rings, i.e. PPAPE/IPA will be also addressed.
F
F
F
O
O
F
F
O
NH2
H2N
NH2
H2N
IR and NMR spectroscopy results of PNPE and PAPE obtained
from our simple two-step method were thoroughly conformable to
those reported beforehand. On the other hand, our strategy to
synthesize FPAPE was similar to synthesis of PAPE. Synthesis of
FPAPE has been stated elsewhere in depth [30]. Scheme 1 outlines
the synthetic route to these diamines. Fluorinated diamine FPAPE
was then utilized to prepare the corresponding poly(ether-amide)s
through reacting with four aromatic diacid comonomers. The
highly fluorinated all-aromatic poly(ether-amide)s including
FPAPE/TPA, FPAPE/IPA, FPAPE/2,5-PDA, and FPAPE/2,6-PDA as
well as their two non-fluorinated counterparts, i.e. PAPE/IPA
(lacking fluorine atoms attached to the lateral phenyl rings) and
ODA/IPA (lacking fluorinated phenyl lateral groups), were pre-
pared by phosphorylation method, similarly. This method involves
the one-pot polycondensation of aromatic diacids with aromatic
diamines in the presence of an aryl phosphite such as triphenyl
phosphite (TPP) and an organic base such as pyridine [34–36]. All
the polyamidation reactions proceeded smoothly in homogeneous
solutions with a high yield (over 90%). Scheme 2 shows the
reaction route to prepare the resulting fluorinated polymers. The
synthetic route to the reference poly(ether-amide)s (PAPE/IPA and
ODA/IPA) is also shown in Scheme 3.
F
O
PPAPE
FPAPE
FPAPE was then used to prepare a number of fluoro-containing
aromatic polyimides. In the present study, however, we will report
the synthesis and characterization of novel highly fluorinated
aromatic polyamides derived from diamine FPAPE and four simple
diacid comonomers. Experimentally, to attain further results,
polymers derived from 2,20-diphenyl-4,40-diaminodiphenyl ether
(PAPE) possessing lateral phenyl rings but lacking any fluorine
atom as well as polymers derived from 4,40-oxydianiline (4,40-
ODA) lacking fluorinated phenyl lateral groups were also prepared
to compare their characteristics with those of the polymers
prepared from FPAPE. Solubility in common organic solvents,
crystallinity of the macromolecular chains, intrinsic viscosity of the
polymers solutions, and thermal stability were subsequently
investigated.
2. Results and discussion
Some characteristics of the fluorinated and non-fluorinated
poly(ether-amide)s including lmax values by means of UV–vis
spectroscopy and their apparent color are tabulated in Table 1. FT-
IR and 1H NMR spectroscopy were used to confirm the structure of
the resulting poly(ether-amide)s. In the infrared spectra, the
absorptions of amide groups appear at about 3350 cmꢀ1 (N–H
stretch) and 1650 cmꢀ1 (C55O stretch). Fig. 1 (top) shows FT-IR
spectrum of the polymer FPAPE/IPA. 1H NMR spectra of the fluoro-
containing polymers showed amide protons peak at about
10.55 ppm. Fig. 1 (bottom) shows proton-assigned 1H NMR
spectrum of the same polymer FPAPE/IPA. In this spectrum only
the region of appearance of aromatic protons can be observed,
instead all data obtained from 1H NMR spectroscopy of the
2.1. Synthesis
PAPE was synthesized starting from DINPE by a two-step
manner. In the first step, DINPE was reacted with phenylboronic
acid via a Suzuki coupling reaction affording yellow needles of 2,20-
diphenyl-4,40-dinitrodiphenyl ether (PNPE). In the second step,
PNPE was reduced to obtain pale yellow solids of PAPE. It should be
noted that PAPE has been synthesized previously by Morikawa et
al. [33] via a manner other than that of used by us. They
synthesized PAPE via a more complicated method (a five-step
pathway starting from 3-chloro-4-fluoronitrobenzene), and then
applied it to prepare some aromatic polyimides (not polyamides).
One of their synthesized polyimides, for example that of obtained
Pd(PPh3)4
X
I
Toluene/H2O
O2N
O
NO2
+
X
B(OH)2
O2N
O
NO2
Reflux
I
X
DINPE
X= Ph : PNPE
X= F3-Ph : FPNPE
N2H4. H2O
C2H5OH
X
H2N
O
NH2
Pd/C
X
X= Ph : PAPE
X= F3-Ph : FPAPE
X
F
F
,
F
Scheme 1. Synthetic route to diamines FPAPE and PAPE.

278
H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
F
F
F
F
TPP / Pyridine
NMP / CaCl2
H2N
O
NH2
+
HOOC-Ar-COOH
F
N2 atm.
F
F
F
F
O
O
Ar
HN
O
NH C
C
n
F
F
F
HOOC-Ar-COOH
O
HO C
O
C OH
O
C OH
O
C
N
HO
O
HO C
O
C OH
O
C OH
O
C
HO
N
Scheme 2. Synthetic route to the fluorinated poly(ether-amide)s.
X
TPP / Pyridine
NMP / CaCl2
O
O
C OH
H2N
O
NH2
+
HO C
N2 atm.
X
X
O
NH C
O
C
HN
O
n
X
X
,
H
Scheme 3. Synthetic route to the reference non-fluorinated poly(ether-amide)s.
poly(ether-amide)s are tabulated in Table 2. In all cases, chemical
shifts and integral values of the peaks are compatible with the type
and the number of attributed hydrogens.
done. [
values for all polymeric solutions were determined through the
extrapolation of the concentrations used to zero. The [ ] values
h] was obtained as the y-axis intersect. In other word, these
h
(intrinsic viscosities) in DMAc at 30 8C is tabulated in Table 1. The
2.2. Solution viscosity
high molecular weights of the polymers might be confirmed by the
high [h
] values (up to 1.0 dL gꢀ1) as well as the absence of
Solution viscosity can be used to estimate an average molecular
weight because it is a general rule that the more extended any
macromolecule is, the more viscose solution bearing it will be. For
polymeric materials there is a definite relationship between
molecular weight and solution viscosity [37]. The limited viscosity
detectable end groups (NH2 or COOH) in the FT-IR and 1H NMR
spectra of the resulting poly(ether-amide)s.
2.3. Organo-solubility
numbers ([
h
h
] values) were measured from their specific viscosities,
The solubility behavior of the resulting fluorinated poly(ether-
amide)s was tested qualitatively in various organic solvents. Table
3 shows the results obtained from this part of our study. All fluoro-
containing poly(ether-amide)s could be easily dissolved in polar
sp, at concentrations 0.1, 0.2, 0.3, 0.4, and 0.5 g dLꢀ1 in N,N-
dimethylacetamide (DMAc) at 30 8C. The hsp values were plotted
against the concentrations used, and linear extrapolation was

H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
279
Table 1
Some characteristics of the resulting fluorinated and non-fluorinated poly(ether-amide)s, and poly(ether-imide).
(dL gꢀ1
)
a
b
Polymer
Chemical formula
lmax (nm)
Color
[
h
]
c
FPAPE/TPA
277
Pale yellow
–
F
F
F
O
O
C
HN
HN
HN
O
NH C
n
n
n
F
F
F
F
F
F
FPAPE/IPA
265
Pale cream
1.11
F
O
C
O
O
NH C
F
F
F
F
FPAPE/2,5-PDA
274
Pale gray
1.07
F
O
O
C
N
O
NH C
F
F
F
F
F
FPAPE/2,6-PDA
269
White
1.01
F
F
O
C
O
HN
O
NH C
N
n
n
F
F
PAPE/IPA
281
Cream
0.98
O
C
O
HN
HN
O
NH C
c
ODA/IPA
928
266
Pale brown
–
O
O
C
O
NH C
n
PPAPE/IPAd
O
Brown
0.80
O
C
O
HN
HN
O
NH C
n
O
f
f
PAPE/PDAe
–
–
0.87g
O
N
O
O
N
n
O
O
a
Measured in DMSO.
b
Measured in DMAc at 30 8C.
c
Was not dissolved in DMAc adequately.
Data obtained from Ref. [31].
Data obtained from Ref. [33].
Not reported.
d
e
f
g
Inherent viscosity of the related poly(amic acid) measured at 0.5 g dLꢀ1 in NMP at 30 8C.

280
H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
Fig. 1. IR (top) and 1H NMR (bottom) spectra of the poly(ether-amide) FPAPE/IPA.
organic solvents such as dimethyl sulfoxide (DMSO), DMAc, N,N-
dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) at
room temperature or upon heating at about 70 8C. This class of
polymers was nearly dissolved even in less polar solvents
including pyridine and tetrahydrofuran (THF) upon heating.
Fluorine and fluoro-containing substituents endow a large amount
of polarity due to the high electronegativity of fluorine atoms, and
thereby fluoropolymers show good organo-solubility, particularly
in polar solvents. Furthermore, the good solubility of these all-
aromatic poly(ether-amide)s might be caused by an entropy
advantage resulted from the bulky fluorinated phenyl groups that
inhibited the close packing of the polymer chains. According to
this, the highly fluorinated aromatic poly(ether-amide)s showed a
further solubility in polar solvents when compared to their non-
fluorinated counterparts. The order of 4,40-ODA/IPA < PAPE/
IPA < FPAPE/IPA ꢁ PPAPE/IPA gives a qualitative indication of
the trend in organo-solubility. Although bulky phenoxy lateral
groups in PPAPE/IPA may disrupt order of the chains further in
comparison with small fluorine atoms in FPAPE/IPA, the less steric
effect of fluorine atoms is balanced by the extra organo-solubility
in polar solvents gained from the electronic effects of the fluorine
atoms. Moreover, some other trends could be also detected from
the table, such as the order of FPAPE/TPA < FPAPE/IPA or PAPE/
PDA < PAPE/IPA. Also, the pyridyl-based poly(ether-amide)s, i.e.
FPAPE/2,5-PDA and FPAPE/2,6-PDA were somewhat more soluble
than those of prepared from terephthalic acid (TPA) or isophthalic
acid (IPA) diacid comonomers.
phenyl pendant groups on the crystallinity extent, wide-angle X-ray
diffraction (WXRD) measurements at room temperature in the
region of 2u = 10–508 were done for poly(ether-amide)s FPAPE/IPA
and 4,40-ODA/IPA. The diffraction patterns are presented in Fig. 2.
According to the diffractograms obtained, only one broad peak was
observed in the range of 10–308, and almost no crystal diffraction
was detected for this class of new fluorinated aromatic poly(ether-
amide)s. This amorphous diffraction pattern is reasonable because
the presence of the bulky fluorinated phenyl groups attached to the
macromolecular backbone induces looser chain packing and
decreases the intermolecular forces between the polymer chains
causing a decrease in crystallinity. In fact, introducing bulky
substituents within the macromolecular chains decreases the
well-organized arrangement of the chains. On the other hand, it
seems to be a true statement that the enhancement of polarity of the
chains endowed by fluorine atoms in these highly fluorinated
poly(ether-amide)s enhances crystallite regions of them to a large
extent by increasing intermolecular forces, causing
a more
crystallinity amount. However, the results obtained from the
fluorinated poly(ether-amide)s clearly show that the steric factor
caused by bulky fluorinated phenyl lateral groups outweighs the
polarity factor derived from fluorine atoms. Hence, the steric effects
are the dominant factor in crystallinity here, and only the minor
effect with a opposite direction is believed to be electronic.
2.5. Thermogravimetric analysis (TGA)
Thermal stability of the resulting poly(ether-amide)s were
evaluated by thermogravimetric analysis (TGA) under nitrogen
atmosphere at a heating rate of 10 8C minꢀ1. The results obtained
from TGA analyses are tabulated in Table 4. TGA thermograms
showed that the highly fluorinated poly(ether-amide)s obtained
2.4. X-Ray diffraction patterns
In order to study the crystallinity amount of the fluorinated
poly(ether-amide)sand toinvestigatethe effect of fluoro-containing

H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
281
Table 2
1H NMR results of the resulting poly(ether-amide)s.
Polymer
Formula
1H NMR results (ppm)
F
F
FPAPE/TPA
10.55 (2H, amide-H), 8.04 (4H, He), 7.39 (6H, Ha & Hb & Hc),
6.10 (4H, Hd)
d
F
F
e
O
NH C
O
C
a
HN
O
n
b
c
F
F
F
F
FPAPE/IPA
10.53 (2H, amide-H), 8.49 (1H, He), 8.15 (2H, Hf), 7.61
(1H, Hg), 7.39 (6H, Ha & Hb & Hc), 6.10 (4H, Hd)
d
F
O
C
O
a
e
HN
O
NH C
n
b
c
f
g
F
F
F
F
F
FPAPE/2,5-PDA
10.53 (2H, amide-H), 9.15 (1H, He), 8.43 (1H, Hf), 8.14 (1H, Hg),
7.39 (6H, Ha & Hb & Hc), 6.09 (4H, Hd)
d
F
O
C
O
a
b
e
N
f
HN
HN
O
NH C
n
c
g
F
F
F
F
FPAPE/2,6-PDA
10.54 (2H, amide-H), 8.23 (2H, He), 8.18 (1H, Hf), 7.38
(6H, Ha & Hb & Hc), 6.10 (4H, Hd)
F
d
F
O
C
O
NHC
a
O
N
n
b c
F
e
f
F
F
f
e
PAPE/IPA
10.53 (2H, amide-H), 8.49 (1H, Hg), 8.14 (2H, Hh), 7.61
d
O
C
O
(1H, Hi), 7.25–7.47 (16H, H’sa–f)
a
b
g
i
HN
O
NH C
c
n
h
Table 3
Solubility of the resulting fluorinated and non-fluorinated poly(ether-amide)s.
Solventa
FPAPE/TPA
FPAPE/IPA
FPAPE/2,5-PDA
FPAPE/2,6-PDA
PAPE/IPA
4,40-ODA/IPA
PPAPE/IPAb
PAPE/PDAc
d
DMSO
DMAc
DMF
+
++
++
+
+
++
++
++
++
++
+
+
+
++
++
+
–
+
++
+
++
+
ꢂ
ꢂ
ꢂ
ꢂ
ꢀ
ꢀ
ꢀ
++
++
++
++
ꢀ
+
NMP
+
++
++
+
+
+
++
d
Pyridine
THF
+
+
+
–
ꢀ
ꢀ
ꢀ
ꢂ
ꢀ
ꢀ
ꢂ
ꢀ
ꢀ
ꢂ
d
d
DCM
ꢂ
ꢂ
–
–
d
Toluene
ꢀ
ꢂ
ꢂ
–
++, soluble at room temperature; +, soluble on heating; ꢂ, partially soluble or swollen; and ꢀ, insoluble even on heating.
a
Qualitative solubility was determined with 10 mg of polymer in 1 mL of solvent.
b
Data obtained from Ref. [31].
c
As a poly(ether-imide); data obtained from Ref. [33]. According to the paper cited in this reference, ++ means ‘‘soluble on heating’’.
Not reported.
d
here were stable up to 450 8C. However, a poly(ether-imide) had a
attached fluoro-containing phenyl rings have somewhat an
enhancing effect on the thermal stability of the poly(ether-amide)s.
Furthermore, the order PAPE/IPA < FPAPE/IPA showed that the
fluorine atoms directly linked to the phenyl rings have an increasing
effect on thermo-stability. One of the most important factors for
thermo-stability of fluorinated polyamides is bond energy of C–F. In
fact, a strong C–F bond leads to high thermal and chemical stabilities
higher stability toward heat comparing with its poly(ether-amide)
analog. The poly(ether-amide)s derived from pyridyl-based diacids,
i.e. 2,5-pyridine dicarboxylic acid (2,5-PDA) and 2,6-pyridine
dicarboxylic acid (2,6-PDA) were somewhat more stable toward
heat than those of derived from TPA or IPA. From the order 4,40-ODA/
IPA < FPAPE/IPA, it will be readily revealed that the laterally

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H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
Fig. 2. X-ray diffraction patterns of the poly(ether-amide)s FPAPE/IPA (top) and
ODA/IPA (bottom).
of fluorinated polymers [39]. A representative TGA thermogram for
the fluorinated poly(ether-amide) FPAPE/TPA is presented in Fig. 3
(top). As the profile shows, the char yield at 700 8C for this polymer
was over 45%, and the plateau region proceeded to about 450 8C.
Fig. 3. TGA (top) and DSC (bottom) thermograms of the poly(ether-amide) FPAPE/
TPA.
2.6. Differential scanning calorimetry (DSC)
To (the ‘‘onset’’ temperature, defines the point at which the first
deviation from the base line on the low temperature side is
observed) and Tg (T0.5, temperature of 50% transition) values of the
four fluoro-containing aromatic poly(ether-amide)s and their two
non-fluorinated analogs were determined by differential scanning
calorimetry (DSC) measurements. These values for the two
pyridyl-based poly(ether-amide)s FPAPE/2,5-PDA and FPAPE/2,6-
PDA were about 10 8C grater than those of the other two
fluoropolymers, i.e. FPAPE/TPA and FPAPE/IPA. This might be
due to the presence of nitrogen heteroatoms in the heteroaromatic
rings that limit free rotation of the macromolecular chains by
forming excessive H-bond with hydrogen atoms of amide groups.
This limitation in free rotation of the chains leads reasonably to an
enhancement in To and Tg values. In addition to the mentioned
excessive H-bonds caused by nitrogen heteroatoms, the order 4,40-
ODA/IPA < FPAPE/IPA revealed that the incorporation of bulky
fluoro-containing phenyl pendant groups into the chemical
structure of the polymers restricts the free rotation of their
macromolecular chains and consequently leads to an enhanced Tg
value. According to the results obtained, poly(ether-imide) PAPE/
PDA showed Tg about 70 8C greater than poly(ether-amide) PAPE/
IPA. This could be attributed to the presence of imide heterocyclic
ring that increases rigidity of the chains. There is also a less
dramatic but consistent trend which reveals that fluorine atoms
attached to the phenyl lateral groups have more increasing effect
on Tg values than phenoxy groups attached to them (PPAPE/
Table 4
Some characteristics of the resulting fluorinated and non-fluorinated poly(ether-
amide)s, and poly(ether-imide).
a
b
c
d
Polymer
Td5% (8C)
Td10% (8C)
To (8C)
Tg (8C)
FPAPE/TPA
456
451
460
456
443
448
467
233
229
242
235
228
227
239
241
247
245
235
232
196
309
FPAPE/IPA
464
FPAPE/2,5-PDA
FPAPE/2,6-PDA
PAPE/IPA
4,40-ODA/IPA
PPAPE/IPAf
PAPE/PDAh
471
468
452
459 (450)e
525
g
g
–
g
–
g
–
622
–
a
Temperature at which 5% weight loss was recorded by TGA in N2 atmosphere.
Temperature at which 10% weight loss was recorded by TGA in N2 atmosphere.
Onset temperature, from the second heating traces of DSC measurements in N2.
Temperature of 50% transition, from the second heating traces of DSC
b
c
d
measurements in N2.
e
Data obtained from Ref. [38].
f
Data obtained from Ref. [31].
g
Not reported.
h
Data obtained from Ref. [33].

H. Behniafar, M. Sedaghatdoost / Journal of Fluorine Chemistry 132 (2011) 276–284
283
IPA < FPAPE/IPA). A more restriction in free rotation of the chains is
caused by fluorine atoms relative to phenoxy groups. This
restriction itself might arise from the enhancement in polarity
and consequently in intermolecular attractions. The results
obtained from the DSC analyses are tabulated in Table 4. A typical
DSC plot for the same poly(ether-amide) FPAPE/TPA are presented
in Fig. 3 (bottom).
pyridine were purified by distillation under reduced pressure over
˚
calcium hydride and stored over 4 A molecular sieves. THF and
toluene were dried by sodium before use. Dichloromethane (DCM)
was used without further purification.
4.3. Synthesis of 2,20-diphenyl-4,40-dinitrodiphenyl ether (PNPE)
DINPE (0.5120 g, 1 mmol), Pd(PPh3)4 (0.0346 g) and sodium
carbonate (0.3921 g) were placed in a three-necked flask. A
mixture of toluene/water (1:1) (7.5 mL) was added to the reaction
vessel. Before the reaction took place, the solution was purged with
a slow stream of nitrogen for 15 min and then phenylboronic acid
(0.2682 g, 2.2 mmol) was introduced into the solution. The
reaction mixture was stirred under reflux for 7 days. Upon cooling,
the solution mixture formed two phases, a green solution phase
and a brown oily solid phase. They were isolated from each other,
and the brown oily phase was purified by ethyl acetate/n-hexane
(1:2) to afford 0.3340 g PNPE as yellow solids precipitated at the
bottom of the vessel (81% yield); m.p. 142–144 8C (Lit. 143–144)
[33]. The fluorinated dinitro FPNPE was synthesized similarly.
3. Conclusions
FPAPE as a diphenyl ether-based diamine containing two
fluorinated phenyl lateral groups in its chemical structure was
successfully utilized to prepare some highly fluorinated aro-
matic poly(ether-amide)s. All fluoro-containing polymers were
amorphous and had good solubility in polar organic solvents due
to the presence of bulky phenyl groups possessing three directly
attached fluorine atoms along the chains. The fluoro-containing
poly(ether-amide)s synthesized from FPAPE had higher Tg
values and thermal stability when compared to their non-
fluorinated counterparts. Therefore, no noticeable drawback like
insolubility, intractability, and thermal sensitivity that often
limit utilities in various advanced technological applications
was observed for the FPAPE-derived poly(ether-amide)s. The
results obtained from this study clearly showed that the highly
4.4. Synthesis of 2,20-diphenyl-4,40-diaminodiphenyl ether (PAPE)
To a stirred suspension solution of PNPE (0.4124 g, 1 mmol) and
10% Pd/C (0.0060 g) in ethanol (2.5 mL), a solution of hydrazine
monohydrate (1.1 mL) and ethanol (1.5 mL) was added dropwise
at 70–80 8C over a period of 2 h. After complete addition, the
mixture was heated at reflux temperature for another 24 h. The hot
reaction solution was filtered to remove Pd/C, and the filtrate was
then distilled using a rotary evaporator to remove the solvent. The
crude product was purified by recrystallization from ethanol to
give 0.2784 g of PAPE cream crystals (79% yield); m.p. 204–206 8C
(Lit. 204–205) [33]. The fluorinated diamine FPAPE was synthe-
sized similarly.
fluorinated diamine FPAPE as
a structurally well-designed
monomer can be considered as a good candidate to prepare
the corresponding heat-resistant aromatic polymer. In addition,
it can be concluded that good solubility, moderate Tg values and
excellent thermal stability make these ether-hinged fluorinated
polyamides promising as high-performance polymeric materi-
als.
4. Experimental
4.1. Measurements
4.5. Preparation of the fluorinated poly(ether-amide)s
The limited viscosity number values of the polymers solutions
were determined using an Ubbelohde viscometer. FT-IR spectra
were recorded on a PERKIN ELMER RX I FT-IR spectrometer. The
spectra of solids were obtained using KBr pellets. 1H NMR spectra
were recorded with a Bruker AVANCE 500 NMR operated at
500 MHz for proton using DMSO-d6. Thermal gravimetric analysis
(TGA) and DSC were performed on a METTLER TA 5000 system
(Columbus, OH) under nitrogen atmosphere at a heating rate of
10 8C minꢀ1. The DSC traces were obtained from heating, rapid
cooling, and reheating of samples in a range of 50–400 8C.
A typical example of the polyamidation reactions by phosphor-
ylation method is as follows. A mixture of FPAPE (0.462 g, 1 mmol),
IPA (0.166 g, 1 mmol), calcium chloride (0.350 g), TPP (0.8 mL),
pyridine (1.2 mL) and NMP (4.0 mL) was refluxed for 3 h. After
cooling, the reaction mixture was poured into a large amount of
methanol with constant stirring to isolate polymer FPAPE/IPA. The
precipitated polymer was separated by vacuum filtration and
washed thoroughly with methanol (35 mL) and hot water
(100 mL), and dried at 120 8C under vacuum for 24 h. The other
fluorinated poly(ether-amide)s were synthesized in a similar
manner. The yields of all polycondensation reactions were above
90%. The limited viscosity number values in DMAc at 30 8C as well
Ultraviolet maximum wavelength (lmax) values were determined
with a GBC model 916 ultraviolet–visible (UV–vis) instrument
(GBC Scientific Equipment, Australia) in DMSO at a concentration
of 0.1 mg mLꢀ1
.
WXRD patterns were performed at room
as the ultraviolet lmax values in DMSO were also measured and the
temperatures with film specimens on a D8 ADVANCE BRUKER
data obtained along with subjects associated with IR, NMR,
organo-solubility results, WXRD, TGA, and DSC analyses were
reported and discussed in Section 2.
X-ray diffractometer with Ni-filtered Cu-K radiation (30 kV,
a
25 mA).
4.2. Materials
Acknowledgements
Phenylboronic acid (from MERCK, m.p. 216–219 8C) and 3,4,5-
trifluorophenylboronic acid (from MERCK, m.p. 283–288 8C) were
used as received. All diacid comonomers including TPA (from
MERCK, m.p. 227–228 8C), IPA (from MERCK, m.p. 341–343 8C),
2,5-PDA (from MERCK, m.p. 256–258 8C), and 2,6-PDA (from
MERCK, m.p. 248–250 8C) were used as received without further
purification. 4,40-ODA (from MERCK, m.p. 188–192 8C) was
purified by recrystallization from ethanol before use. DINPE was
synthesized from 4,40-dinitrodiphenyl ether as reported previously
[31]. Solvents used including NMP, DMAc, DMF, DMSO and
TheauthorswishtoexpresstheirgratitudetotheSharifUniversity
of Technology for running the NMR spectra as well as Amir-Kabir
University of Technology for running the TGA and DSC analyses.
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