The effect of fluorine atoms on gas transport properties of new polynorbornene dicarboximides

Article abstract of DOI:10.1016/j.jfluchem.2008.09.011

The new N-4-trifluoromethylphenyl-norbornene-5,6-dicarboximide (2a) and N-3,5-bis(trifluoromethyl)phenyl-norbornene-5,6-dicarboximide (2b) mixtures of exo and endo monomers were synthesized and polymerized via ring opening metathesis polymerization (ROMP)

Full text of DOI:10.1016/j.jfluchem.2008.09.011

Journal of Fluorine Chemistry 130 (2009) 162–168
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
The effect of fluorine atoms on gas transport properties of new
polynorbornene dicarboximides
a
a
a
a,
*
´
Joel Vargas , Araceli Martınez , Arlette A. Santiago , Mikhail A. Tlenkopatchev
,
b
c,
*
´
˜
Ruben Gavino , Manuel Aguilar-Vega
a
´
´
´
´
Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, CU, Coyoacan, Mexico DF 04510, Mexico
b
c
´
´
´
´
´
Instituto de Quımica, Universidad Nacional Autonoma de Mexico, CU, Coyoacan, Mexico DF 04510, Mexico
´
´
´
Centro de Investigacio´n Cientı´fica de Yucatan A.C., Unidad de Materiales, Calle 43 No. 130, Col. Chuburna de Hidalgo, C.P. 97200, Merida, Yuc., Mexico
A R T I C L E I N F O
A B S T R A C T
Article history:
The new N-4-trifluoromethylphenyl-norbornene-5,6-dicarboximide (2a) and N-3,5-bis(trifluoro-
methyl)phenyl-norbornene-5,6-dicarboximide (2b) mixtures of exo and endo monomers were
synthesized and polymerized via ring opening metathesis polymerization (ROMP) using bis(tricyclo-
hexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-
trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II) to produce the
corresponding polynorbornene dicarboximides Poly-2a and Poly-2b, respectively. The transport of five
gases He, N2, O2, CO2 and CH4 across membranes prepared from Poly-2a was determined at 35 8C using a
constant volume permeation cell. The gas transport properties of the fluorine containing polymer Poly-
2a were compared with those found for membranes from non-fluorinated poly(N-phenyl-exo-endo-
norbornene-5,6-dicarboximide) (P-PhNDI). Gas permeability, diffusion and solubility coefficients of the
fluorine containing polynorbornene Poly-2a were up to an order of magnitude larger than those of the
non-fluorinated one. Poly-2a was found to have one of the largest gas transport coefficients reported to
date in glassy polynorbornene dicarboximides.
Received 6 August 2008
Received in revised form 20 September 2008
Accepted 22 September 2008
Available online 2 October 2008
Keywords:
Fluorinated polynorbornene dicarboximide
Ring opening metathesis polymerization
Gas transport properties
ß 2008 Elsevier B.V. All rights reserved.
1. Introduction
transition temperature [10–12]. However, this is not the case for
polynorbornenewithimideside chain groups. Membranes prepared
Fluorine containing polymers have attracted much attention due
to their outstanding properties. These kinds of polymer exhibit high
thermostability, chemical inertness and good hydrophobicity. It is
important to note that low intermolecular and intramolecular
interactions in fluorine containing polymers are important factor for
gas permeability properties of membranes. Thus, we have already
reported gas transport properties of polynorbornenes containing
adamantyl, cyclohexyl and cyclopentyl imide side chain groups [1–
5]. Theseglassy polynorbornenedicarboximides showed high Tg and
good physical and mechanical properties. For example, poly(N-
adamantyl-norbornene-5,6-dicarboximide) (P-AdNDI) showed a Tg
of 271 8C [6]. Even though polynorbornene dicarboximides, such as
P-AdNDI, have bulky pendant groups, their gas permeability
coefficientsarenothighbutsimilartothoseofamorphouspolyesters
or polyamides [7–9]. It is well known, that in many cases higher
permeabilities are found for glassy polymers with higher glass
fromthesepolymersshowanenhancementoftheselectivity,though
thepermeabilityremainslowanddoesnotdependonthebulkofside
chain groups. The low gas permeabilityofthese membranesisdue to
strong intermolecular interactions of polar C O and C–N bonds in
polynorbornene dicarboximides. It is expected that the introduction
of fluorine atoms into polynorbornene dicarboximides will decrease
interchain interactions between polar imide side chain groups and
this effect will increase the gas permeability across them without
detriment to the selectivity. The ROMP of norbornene derivatives
with various fluorine-containing units is well established [13–16].
With the aim of investigating the effect of fluorine atoms on gas
permeability of polynorbornene dicarboximides, the new poly(N-
4-trifluoromethylphenyl-exo-endo-norbornene-5,6-dicarboxi-
mide) (Poly-2a) was synthesized and gas transport properties of
membranes prepared from this polymer were studied.
2. Results and discussion
Monomers 2a and 2b were prepared in high yields. 4-
* Corresponding author. Tel.: +52 5556224586; fax: +52 5556161201.
E-mail address: tma@servidor.unam.mx (M.A. Tlenkopatchev).
Trifluoromethyl aniline and 3,5-bis(trifluoromethyl) aniline
0022-1139/$ – see front matter ß 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2008.09.011

J. Vargas et al. / Journal of Fluorine Chemistry 130 (2009) 162–168
163
Scheme 1. Synthesis of monomers 2a and 2b, respectively.
reacted with NDA to the corresponding amic acids (1a, 1b) which
were cyclized to imides using acetic anhydride as dehydrating
agent (Scheme 1). 1H, 13C and 19F NMR spectra and elemental
analysis confirmed monomer structure and purity. The infrared
spectra of monomer showed characteristic peaks at 1774 and
Mn = 1.11–1.17) due to the slower initiation of the latter catalyst
[18].
Catalyst I gave polymers with predominantly trans configura-
tion of the double bonds (75–84%), whereas catalyst II produced
polymers with a mixture of cis and trans double bonds (50–56% of
cis structure).
Fig. 1 shows the 1H NMR spectra of (a) monomer 2a and (b)
polymer Poly-2a prepared using I. The exo and endo monomer
1706 cmꢀ1 (asymmetric and symmetric
C
O
stretching),
1383 cmꢀ1 (C–N stretching). ROMP of 2a and 2b using ruthenium
catalysts I and II were carried out in 1,2-dichloroethane at 45 8C
(Table 1). Table 1 summarizes the results of the polymerizations of
2a, 2b and PhNDI [5]. The mixture of exo and endo monomers
reacted in 2 h giving polymer in high yield (98–99%, entries 4, 8 and
12). The results obtained by GPC analysis show that the number
average molecular weights (Mn) were between 98,000 and
341,000. The experimental number average molecular weights
are in agreement with the theoretical ones. As shown in Table 1,
the molecular weight distribution (MWD) of the polymers Poly-2a,
Poly-2b and P-PhNDI obtained using II is about Mw/Mn = 1.22–
1.32 which is broader than polymers prepared using I (Mw/
olefinic signals at
d = 6.35–6.25 ppm are replaced by new signals at
d
= 5.80–5.58 ppm, which correspond respectively to the trans and
cis H at the double bonds of the product polymer.
The effect that CF3 group substitutions on the pendant phenyl
ring in the polynorbornene dicarboximide had on the physical
properties of polynorbornenes with similar structures is com-
pared in Table 2. The non-substituted phenyl ring polynorbor-
nene dicarboximide, P-PhNDI, has a higher Tg and Td than the
previously reported poly(exo-N-3,5-bis(trifluoromethyl)phenyl-
7-oxanorbornene-5,6-dicarboximide) P-TFmPhONDI [17] with
the 3,5 CF3 substitution on the phenyl ring, or the single CF3
substitution on the para position of the phenyl ring in Poly-2a.
The latter presents the lowest Tg and Td values although the Td’s
are all above 400 8C which indicates that all these polynorbor-
nenes are of relatively high thermal stability. The lowering of Tg
Table 1
Polymerization conditions of norbornene dicarboximides.
Entry
Monomera
Catalyst
M/Catb
Yieldc
(%)
cisd
Mn ꢁ 10ꢀ5e MWDe
(%)
for the fluorine substituted polymers is attributed to
a
1
2
3
4
2a
2a
2a
2a
I
1000
500
94
96
98
99
16
17
53
52
2.79
1.42
2.61
1.51
1.11
1.12
1.27
1.26
diminished ability to pack of the phenyl ring since the presence
of CF3 moieties in position 3,5 of the phenyl ring inhibits packing
and decrease the temperature to attain the relaxation process.
The single CF3 moiety in the para position of the phenyl ring,
Poly-2a, increases mobility mainly because it has the CF3 group
situated on the phenyl ring in a symmetric manner. Density
measurements, reported also in Table 2, indicate that the
presence of two CF3 moieties increases density of the poly-
norbornene dicarboximide (P-TFmPhONDI), followed by the one
with a single CF3 substitution, Poly-2a, as compared to the non-
fluorine substituted polynorbornene dicarboximide, P-PhNDI. It
is also reported in Table 2 the fractional free volume (FFV), as
calculated from Bondi’s group contribution method from the
following equation [19];
I
II
II
1000
500
5
6
7
8
2b
2b
2b
2b
I
1000
500
91
93
94
98
18
20
51
50
3.41
1.77
3.27
1.62
1.15
1.17
1.22
1.23
I
II
II
1000
500
9
10
11
12
PhNDIf
PhNDIf
PhNDIf
PhNDIf
I
1000
500
92
95
96
98
22
25
55
56
2.21
1.09
2.10
0.98
1.16
1.17
1.30
1.32
I
II
II
1000
500
a
1,2-Dichloroethane as solvent, Temperature = 45 8C, Time = 2 h, Initial mono-
mer concentration [Mo] = 0.7 mol/L.
b
Mole ratio of monomer to catalyst.
c
Methanol insoluble polymer.
Determined by 1H NMR.
d
e
ðV ꢀ VOÞ
GPC analysis in chloroform with polystyrene calibration standards.
FFV ¼
(1)
f
Poly(N-phenyl-exo,endo-norbornene-5,6-dicarboximide) [5].
V

164
J. Vargas et al. / Journal of Fluorine Chemistry 130 (2009) 162–168
Fig. 1. 1H NMR spectra of monomer 2a (bottom) and polymer Poly-2a (top) obtained using catalyst I.
Table 2
Physical properties of polynorbornene dicarboximides.
Polymer
Tg (8C)
Td (8C)
FFV
r
(g/cm3)
s
(MPa)
E (MPa)
155
402
0.141
1.368
55.4
1408
182
404
0.230
1.430
43.2
1512

J. Vargas et al. / Journal of Fluorine Chemistry 130 (2009) 162–168
165
Table 2 (Continued )
Polymer
Tg (8C)
Td (8C)
FFV
r
(g/cm3)
s
(MPa)
E (MPa)
222
418
0.126
1.241
57.0
1560
aPoly(N-4-trifluoromethylphenyl-exo,endo-norbornene-5,6-dicarboximide).
bPoly(exo-N-3,5-bis(trifluoromethyl)phenyl-7-oxanorbornene-5,6-dicarboximide) [17].
cPoly(N-phenyl-exo,endo-norbornene-5,6-dicarboximide) [5].
where V is the specific volume (1/
volume which according to Bondi’s method can be calculated from
the Van der Waals volume, Vw as Vo = 1.3 Vw.
r
), Vo is the specific occupied
order of magnitude higher than those of the polynorbornene
dicarboximide without fluorine groups, P-PhNDI. The larger gas
permeability coefficients in the CF3 substituted polynorbornenes
are related to the larger FFV, which in turn facilitates the diffusion
of the gas molecules through the polymer. The latter result is
clearly seen by the increase in gas diffusion coefficients, D, as the
number of CF3 groups increases in the polynorbornene. As a
general trade off when the gas permeability coefficients increase,
the gas separation capacity or ideal gas separation factor, as
defined for Eq. (2), decreases for a given pair of gases:
FFV is a measure of the intermolecular distance between
polymer chains. From Table 2 FFV increases drastically with the
presence of CF3 groups on the pendant phenyl moiety in the
polynorbornene dicarboximides. FFV of P-TFmPhONDI is almost
twice that of the non-substituted polynorbornene, P-PhNDI. The
increase in FFV is related to a larger intermolecular distance
between the polymer chains, which is related to an inhibition of
packing by the presence of the CF3 groups.
The presence of CF3 moieties in the phenyl ring of the
polynorbornene dicarboximide structures becomes important
for their gas permeability coefficients, see Table 3. It is seen that
the polynorbornene dicarboximide with two CF3 substitutions and
the larger FFV, P-TFmPhONDI, has around twice the gas
permeability coefficients found for the polynorbornene dicarbox-
imide with a single CF3 substitution, Poly-2a. While the latter has
gas permeability coefficients that are with the exception of CO2 an
PA
aBA
¼
(2)
PB
where PA and PB are the pure gas permeability coefficients for gases
A and B. In Table 3 the ideal gas separation factors for the
commercially important gas mixtures O2/N2 and CO2/CH4 are
presented. They follow the expected trend since as the perme-
ability coefficient increases in the polynorbornene dicarboximide,
the ideal separation factor decreases. However, since the difference
Table 3
Ideal gas separation factors, gas permeability, diffusion and solubility coefficients of fluorinated and non-fluorinated polynorbornene dicarboximides.
P
P
D ꢁ 108 (cm2/s)
S ꢁ 103 cm3(STP)/cm3 cmHg
aBA
¼
A
B
Polymer
P (Barrer)
He
CO2
77.5
O2
N2
3.69
CH4
4.09
CO2
O2
N2
9.1
CH4
5.1
CO2
O2
N2
CH4
O2/N2
4.21
CO2/CH4
18.9
80.8
15.5
11.4
15.0
70.5
10.4
4.0
9.7
203.1
164.6
39.4
11.3
10.7
76.0
161
67
20
21.6
2.4
1.6
5.3
3.40
15.3

166
J. Vargas et al. / Journal of Fluorine Chemistry 130 (2009) 162–168
Table 3 (Continued )
P
P
D ꢁ 108 (cm2/s)
S ꢁ 103 cm3(STP)/cm3 cmHg
aBA
¼
A
B
Polymer
P (Barrer)
He
–
CO2
11.4
O2
1.44
N2
0.31
CH4
0.54
CO2
O2
N2
2.2
CH4
0.72
CO2
O2
N2
CH4
O2/N2
4.64
CO2/CH4
21.1
1.81
6.3
63.2
2.2
1.3
7.5
aPoly(N-4-trifluoromethylphenyl-exo,endo-norbornene-5,6-dicarboximide).
bPoly(exo-N-3,5-bis(trifluoromethyl)phenyl-7-oxanorbornene-5,6-dicarboximide) [17].
cPoly(N-phenyl-exo,endo-norbornene-5,6-dicarboximide) [5].
in gas permeability coefficients is at least one order of magnitude
higher in P-TFmPhONDI, as compared to P-PhNDI the CF3
substituted polynorbornene may present an advantage for
developing a technical separation where the large gas permeability
coefficients will compensate for the loss in selectivity for the gas
separation because the loss in selectivity is not large than 1.2.
1125–5500R using a 50 Kg cell at a crosshead speed of 10 mm/min
according to the method ASTM D1708 in film samples of 0.5 mm of
thickness at room temperature. Molecular weights and molecular
weight distributions were determined with reference to poly-
styrene standards on a Varian 9012 GPC at 30 8C in chloroform
using a universal column and a flow rate of 1 mL minꢀ1. Density of
the polynorbornenes was measured by the density gradient
column method for films cast from solution. The gradient was
established by Ca(NO3)2 solutions at 23 8C using glass standards.
Films of Poly-2a, P-TFmPhONDI and P-PhNDI were cast from
chloroform solutions, 5 wt.%, of each polynorbornene at room
temperature. The solutions were dried overnight in a solvent
atmosphere until a self-standing film developed. The films were
transfer to a vacuum oven and kept at 80 8C to insure that
chloroform was totally eliminated. The thickness of the films used
3. Conclusions
Exo(90%)-endo(10%) monomer mixtures 2a and 2b were
synthesized and polymerized via ROMP using well defined
ruthenium alkylidene catalysts I and II. Tg for Poly-2a was
observed at 155 8C. The catalyst I produced polymers with
predominantly trans configuration of the double bonds whereas
catalyst II gave polymers with a mixture of cis and trans double
bonds. A comparison of Poly-2a physical and gas transport
properties with a non-fluorinated analogous P-PhNDI and a
polynorbornene with two CF3 groups in the phenyl ring, P-
TFmPhONDI, was performed. Thermal properties such as Tg and Td
are lower in Poly-2a as compared to those of the analogous non-
fluorinated P-PhNDI, a fact that was attributed to a larger polymer
interchain distance. Density and fractional free volume are larger
in the fluorine substituted polymers due to the presence of the
bulky CF3 groups. The large fractional free volume found in Poly-2a
as compared to the non-fluorine substituted polynorbornene, P-
PhNDI, produces one of the largest permeability and diffusion
coefficients found in polynorbornene dicarboximides.
for gas transport properties was around 75
mm.
Gas transport properties were measured in a constant volume
type gas permeation cell as described elsewhere [3]. Gas
permeability coefficients, P, were determined for pure He, CO2,
O2, N2 and CH4 under steady state conditions at 35 8C and 2
atmospheres upstream pressure. From this transient permeation
experiment, diffusion coefficients, D, for CO2, O2, N2 and CH4 were
obtained using the time lag method as described before [3].
Solubility coefficients, S, were obtained from the ratio between
permeability and diffusion coefficients, S = P/D, for each pure gas.
4.2. Reagents
4. Experimental
Exo(90%)-endo(10%) mixture of norbornene-5,6-dicarboxylic
anhydride (NDA) was prepared via Diels-Alder condensation of
cyclopentadiene and maleic anhydride according to literature
[5]. 4-Trifluoromethylaniline, 3,5-bis(trifluoromethyl) aniline
and other chemicals were purchased from Aldrich Chemical
Co. 1,2-Dichloroethane and dichloromethane were dried over
anhydrous calcium chloride and distilled over CaH2. Bis(tricy-
clohexylphosphine) benzylidene ruthenium(IV) dichloride (I)
and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-
4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium
dichloride (II) were purchased from Aldrich Chemical Co. and
used as received.
4.1. Techniques
1H NMR, 13C NMR and 19F NMR spectra were recorded on a
Varian spectrometer at 300, 75 and 300 MHz, respectively, in
CDCl3. Tetramethylsilane (TMS) and trifluoroacetic acid (TFA) were
used as internal standards, respectively. FT-IR spectra were
obtained on a Nicolet 510 p spectrometer. Glass transition
temperature, Tg, was determined in a DSC-7 Perkin Elmer Inc.,
at scanning rate of 10 8C/min under nitrogen atmosphere. The
sample was encapsulated in a standard aluminum DSC pan. The
sample was run twice in the temperature range 30–300 8C under a
nitrogen atmosphere. Onset of decomposition temperature, Td, was
determined using thermogravimetric analysis, TGA, which was
performed at a heating rate of 10 8C/min under a nitrogen
atmosphere with a DuPont 2100 instrument. Mechanical proper-
4.3. Synthesis and characterization of exo(90%)-endo(10%) monomer
mixture of N-4-trifluoromethylphenyl-norbornene-5,6-dicarboximide
(2a)
ties under tension, Young’s modulus (E) and stress (
s), were
NDA (5 g, 30.5 mmol) was dissolved in 50 mL of dichloro-
measured in a Universal Mechanical Testing Machine Instron
methane. An amount of 4.9 g (30.4 mmol) of 4-trifluoromethylani-

J. Vargas et al. / Journal of Fluorine Chemistry 130 (2009) 162–168
167
line in 5 mL of dichloromethane is added dropwise to the stirred
solution of NDA. The reaction was maintained at reflux for 2 h and
then cooled to room temperature. The precipitate was recovered
by filtration and dried to give 9.7 g of amic acid 1a. The obtained
amic acid 1a (9.7 g, 29.8 mmol), anhydrous sodium acetate (1.1 g,
13.6 mmol) and acetic anhydride (12.0 g, 117 mmol) were heated
at 70–80 8C for 7 h and then cooled. The solid which is crystallized
out on cooling was filtered, washed several times with cold water
and dried in a vacuum oven at 50 8C overnight. A mixture of
exo(90%) and endo(10%) monomers 2a (Scheme 1) was obtained
after two recrystallizations from ethanol: yield = 89%. m.p. = 181–
183 8C.
1H NMR (300 MHz, CDCl3, ppm):
d
7.86–7.69 (3H, m), 6.21 (2H, s),
6.31 (2H, t), 3.55–3.48 (2H, m), 2.82 (2H, s), 1.85–1.63 (2H, m).
13C NMR (75 MHz, CDCl3, ppm):
52.4, 45.6, 37.6.
d
175.8, 134.7, 132.6–120.9,
19F NMR (300 MHz, CDCl3, ppm):
d
ꢀ 62.2.
Anal. Calcd. (%) for C17H11O2F6N (375): C, 54.40; H, 2.93; O,
8.53; F, 30.40; N, 3.93. Found: C, 54.80; H, 2.70; N, 4.06.
4.5. Metathesis polymerization of monomer
Polymerizations were carried out in a glass vial under a dry
nitrogen atmosphere. After terminating the polymerization by
addition of a small amount of ethyl vinyl ether, the solution was
poured into an excess of methanol. The polymer was purified by
precipitation in methanol from chloroform containing a few drops
of 1N HCl. The obtained polymer was dried in a vacuum oven at
40 8C to constant weight.
FT-IR (KBr):
H sym. str.), 1774 (C O), 1706 (C O), 1519 (C C str), 1460 (C–H
def), 1394 (C–N), 1195, 1169 cmꢀ1
1H NMR (300 MHz, CDCl3, ppm):
n 3029 (C C–H str), 2978 (C–H asym. str.), 2945 (C–
.
d
7.74–7.26 (4H, m), 6.35 (1H,
s), 6.25 (1H, s), 3.41 (2H, m), 2.87 (2H, s), 1.81–1.20 (2H, m).
13C NMR (75 MHz, CDCl3, ppm):
52.2, 47.8, 45.8, 45.5, 42.9.
d
176.3, 137.9, 134.6, 126.1,
4.5.1. Polymerization of 2a
19F NMR (300 MHz, CDCl3, ppm):
d
ꢀ 62.0.
Monomer 2a (1.0 g, 3.25 mmol) and catalyst I (2.68 ꢁ 10ꢀ3 g,
0.0032 mmol) were stirred in 4.6 mL of 1,2-dichloroethane at 45 8C
for 2 h (Scheme 2). The obtained polymer Poly-2a was soluble in
chloroformanddichloromethane. Thevaluesofthenumber-average
molecular weight, Mn, polydispersity, Mw/Mn, glass transition (Tg)
and decomposition (Td) temperature of poly(N-4-trifluoromethyl-
phenyl-exo-endo-norbornene-5,6-dicarboximide) were, respec-
tively, Mn = 279,000, Mw/Mn = 1.11, Tg = 155 8C, Td = 402 8C.
Anal. Calcd. (%) for C16H12O2F3N (307): C, 62.54; H, 3.90; O,
10.42; F, 18.56; N, 4.56. Found: C, 62.84; H, 3.62; N, 4.95.
4.4. Synthesis and characterization of exo(90%)-endo(10%) monomer
mixture of N-3,5-bis(trifluoromethyl)phenyl-norbornene-5,6-
dicarboximide (2b)
NDA (5 g, 30.5 mmol) was dissolved in 50 mL of dichloro-
methane. An amount of 7.0 g (30.5 mmol) of 3,5-bis(trifluoro-
methyl) aniline in 5 mL of dichloromethane is added dropwise to
the stirred solution of NDA. The reaction was maintained at reflux
for 2 h and then cooled to room temperature. The precipitate was
recovered by filtration and dried to give 11.5 g of amic acid 1b. The
obtained amic acid 1b (11.5 g, 29.2 mmol), anhydrous sodium
acetate (2.2 g, 26.8 mmol) and acetic anhydride (34.0 g, 333 mmol)
were heated at 90–100 8C for 4 h and then cooled. The solid which
is crystallized out on cooling was filtered, washed several times
with cold water and dried in a vacuum oven at 50 8C overnight. A
mixture of exo(90%) and endo(10%) monomers 2b (Scheme 1) was
obtained after two recrystallizations from hexane: yield = 92%.
m.p. = 105–108 8C.
FT-IR (film):
(C–H sym str), 1782 (C O), 1714, 1617, 1519 (C C), 1452, 1374
(C–N), 1171, 1125 cmꢀ1
1H NMR (300 MHz, CDCl3, ppm):
s, trans), 5.58 (1H, s, cis), 3.18 (2H, s), 2.87 (2H, s), 2.23 (1H, s), 1.70
(1H, s).
n 3090 (C C–H ar.str), 2953 (C–H asym str), 2886
.
d
7.73–7.26 (4H, m), 5.80 (1H,
13C NMR (75 MHz, CDCl3, ppm):
130.0, 126.4, 121.7, 50.8, 46.1.
19F NMR (300 MHz, CDCl3, ppm):
d
176.5, 134.8, 131.8, 130.4,
d
ꢀ 67.3.
4.5.2. Polymerization of 2b
Monomer 2b (1.0 g, 2.66 mmol) and catalyst I (2.19 ꢁ 10ꢀ3 g,
0.0026 mmol) were stirred in 3.8 mL of 1,2-dichloroethane at 45 8C
for 2 h (Scheme 2). The obtained polymer Poly-2b was soluble in
chloroformanddichloromethane. Thevaluesofthenumber-average
molecular weight, Mn, polydispersity, Mw/Mn, glass transition (Tg)
and decomposition (Td) temperature of poly(N-3,5-bis(trifluoro-
FT-IR (KBr):
H sym str), 1781 (C O), 1712 (C O), 1627 (C C str), 1470 (C–H
def), 1405 (C–N), 1337, 1286, 1181, 1129, 922, 872, 844, 751 cmꢀ1
n 3073 (C C–H str), 2977 (C–H asym str), 2877 (C–
.
Scheme 2. Synthesis of polynorbornene dicarboximides Poly-2a and Poly-2b via ROMP.

168
J. Vargas et al. / Journal of Fluorine Chemistry 130 (2009) 162–168
´
´
[2] A.P. Contreras, M.A. Tlenkopatchev, M.M. Lopez-Gonalez, E. Riande, Macromole-
methyl)phenyl-exo-endo-norbornene-5,6-dicarboximide)
were,
cules 35 (2002) 4677–4684.
respectively, Mn = 341,000, Mw/Mn = 1.15, Tg = 168 8C, Td = 393 8C.
FT-IR (film): 3034 (C C–H ar.str), 2938 (C–H asym str), 2879
(C–H sym str), 1775 (C O), 1598 (C C), 1459, 1365 (C–N), 1295,
1165, 790 cmꢀ1
1H NMR (300 MHz, CDCl3, ppm):
[3] K. Dı´az, J. Vargas, L.F. del Castillo, M.A. Tlenkopatchev, M. Aguilar-Vega, Macromol.
Chem. Phys. 206 (2005) 2316–2322.
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Riande, Macromolecules 28 (2005) 2696–2703.
n
.
[5] J. Vargas, A.A. Santiago, M.A. Tlenkopatchev, R. Gavin˜o, M.F. Laguna, M.M. Lo´pez-
d
7.89–7.69 (3H, m), 5.85 (1H,
´
Gonzalez, E. Riande, Macromolecules 40 (2007) 563–570.
[6] A.P. Contreras, A.M. Cierda, M.A. Tlenkopatchev, Macromol. Chem. Phys. 203
(2002) 1811–1818.
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2625–2638.
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1999–2026.
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s, trans), 5.67 (1H, s, cis), 3.46 (2H, s), 3.09 (2H, s), 2.02 (1H, s), 1.51
(1H, s).
13C NMR (75 MHz, CDCl3, ppm):
126.4, 122.1, 120.9, 48.9, 45.3, 40.6.
19F NMR (300 MHz, CDCl3, ppm):
d
174.0, 133.2, 132.6, 129.1,
d
ꢀ 62.0.
Acknowledgements
We thank CONACyT and DGAPA-UNAM PAPIIT for generous
support with contracts 23432, ES-104307 and IX227904. We are
[14] P.M. Blackmore, W.J. Feast, J. Fluorine Chem. 40 (1988) 331–347.
[15] W.J. Feast, M. Gimeno, E. Khosravi, Polymer 44 (2003) 6111–6121.
[16] W.J. Feast, M. Gimeno, E. Khosravi, J. Mol. Catal. Chem. A 213 (2004) 9–14.
´
grateful to Alejandrina Acosta, Gerardo Cedillo, Salvador Lopez
´
Morales, Miguel Angel Canseco and Alfredo Maciel for their assis-
tance in NMR, GPC, thermal andmechanical properties, respectively.
´
[17] J. Vargas, A. Martınez, A.A. Santiago, M.A. Tlenkopatchev, M. Aguilar-Vega, Poly-
mer 48 (2007) 6546–6553.
[18] A.A. Santiago, J. Vargas, R. Gavin˜o, A.M. Cerda, M.A. Tlenkopatchev, Macromol.
Chem. Phys. 208 (2007) 1085–1092.
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