Comparison of epoxy- and cyclocarbonate-functionalised vinyl ethers in radical copolymerisation with chlorotrifluoroethylene

Article abstract of DOI:10.1016/j.jfluchem.2014.08.014

The synthesis of functional fluoropolymers is a challenging and highly sought-after objective. Fluoroolefins are indeed in their vast majority non-functional. Their specific reactivity however, can be turned into an advantage. Alternating copolymerisation

Full text of DOI:10.1016/j.jfluchem.2014.08.014

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Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Comparison of epoxy- and cyclocarbonate-functionalised vinyl ethers
in radical copolymerisation with chlorotrifluoroethylene
Guillaume Couture, Vincent Ladmiral, Bruno Am e´ duri *
Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, Ing e´ nierie et Architectures Macromol e´ culaires (IAM), 8, rue de l’ e´ cole normale,
Montpellier Cedex 5 34296, France
A R T I C L E I N F O
A B S T R A C T
Article history:
The synthesis of functional fluoropolymers is a challenging and highly sought-after objective.
Fluoroolefins are indeed in their vast majority non-functional. Their specific reactivity however, can
be turned into an advantage. Alternating copolymerisation of electron-acceptor chlorotrifluoroethylene
Received 29 July 2014
Received in revised form 18 August 2014
Accepted 20 August 2014
Available online xxx
(CTFE) and electron-donor vinyl ethers (VEs) is indeed efficient to prepare poly(CTFE-alt-VE)
fluoropolymers with a very high density of functional groups. This article deals with the synthesis of
two original functional vinyl ethers (oxirane and cyclocarbonate), and describes two methods to
synthesise ammonium-containing Hofmannn degradation-insensitive fluoro-copolymers, that may
display interesting properties as component of solid alkaline fuel cell membranes. Both functional vinyl
ethers copolymerised to high yield with CTFE. The oxirane-based monomers led to better defined
alternating copolymers compared to the cyclocarbonate-containing vinyl ether. The post-polymerisa-
tion functionalisation of the copolymers using amines afforded well-defined ammonium-functionalised
fluoro-copolymers.
Keywords:
Alternating copolymers
Cyclocarbonate
Chlorotrifluoroethylene
Vinyl ether
Urethane
Quaternisation
ß 2014 Elsevier B.V. All rights reserved.
1
. Introduction
Fluoropolymers (i.e. polymers bearing fluorine atoms on the
such as high performance elastomers, coatings and textiles,
electronics, aerospace and aeronautics, energy, etc. One of the
main drawbacks of fluoropolymers (that is directly related to their
remarkable properties) is their relative lack of functionalities.
Indeed, the main fluoroolefins, such as TFE (tetrafluoroethylene),
VDF, CTFE, HFP (hexafluoropropene) are non-functional. Preparing
backbone) are a family of niche polymers which display a wide
range of remarkable properties for high tech applications. Some are
elastomers, thermoplastic such as polyvinylidene fluoride (PVDF),
or thermoplastic elastomers (e.g. PVDF-b-poly(VDF-co-hexafluor-
opropylene)-b-PVDF) [1]. They can be semicrystalline like PVDF, or
completely amorphous like poly(chlorotrifluoroethylene-alt-vinyl
ethers) (poly(CTFE-alt-VE)) copolymers. Thanks to the very high
energy required to break the C–F bond, they generally have very
high resistance to temperature, aging, and chemical aggressions
functional fluoropolymers is
a major challenge. Functional
fluoroolefins exist but are rare. For example, the monomer of
1
the NAFION membrane is a perfluorinated vinyl ether that bears a
sulfonyl fluoride end-group.
One of the easiest ways of preparing functional fluoropolymers
is to copolymerise the desired fluoroolefin with a functional
comonomer. Owing to the presence of very electronegative
fluorine atoms, fluoroolefins are in general very electron poor
and show very peculiar reactivity. Indeed, in Alfrey and Price [2,3]
semi-empirical reactivity scale, fluoroolefins occupy a special place
with their Q close to zero and their very positive e value (VDF:
Q = 0.008–0.036, e = 0.4–0.52; TFE: Q = 0.031–0.049, e = 1.22–1.84;
CTFE: Q = 0.020–0.031, e = 1.48–1.84) [2–5]. Q attempts to repre-
sent the extent of the conjugation of the carbon–carbon double
bond with its substituents, while e characterises the electron-
donating (e < 0) or electron-attracting (e > 0) behaviour of the
monomer. Monomers copolymerise well if their Q values are
similar and preferably high. Monomers with similar Q values and
(oxidant, acid and base, except vinylidene fluoride copolymers and
some CTFE-containg copolymers such as poly(CTFE-co-vinylace-
tate)). The fluorinated backbones also endow fluoropolymers with
both hydrophobicity and lipophobicity. In addition, they have
generally very low refractive indices and some of them show very
high electroactivity (ferroelectricity, piezoelectricity, etc). Hence,
these excellent and rare properties enable fluoropolymers to find
high added-value applications in numerous technological fields
*
Corresponding author. Tel.: +33 0 4 67 14 43 68.
E-mail address: Bruno.ameduri@enscm.fr (B. Am e´ duri).
http://dx.doi.org/10.1016/j.jfluchem.2014.08.014
022-1139/ß 2014 Elsevier B.V. All rights reserved.
0
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Scheme 1. General strategy for the synthesis of Hofmann degradation-insensitive poly(CTFE-alt-VE) copolymers using the cyclocarbonate-amine reaction.
high e values of opposite sign tend to copolymerise in alternating
fashion. In general, fluoroolefins, therefore tend to not copolymer-
ise very well with non-fluorinated monomers. One exception is the
case of strong electron-donating monomers with which fluor-
oolefins copolymerisation may occur with a high tendency to
alternation. If the monomer partners are chosen well, it is actually
possible to prepare nearly perfectly alternating copolymers. Such a
couple is the CTFE/vinyl ether couple. PCTFE is a very interesting
polymer due to its excellent film forming properties, its resistance
to chemical attack and its gas barrier property. It is widely used, in
the petrochemical industry in valves, O-rings, seals, shafts and
joints, in the pharmaceutical industry as packaging material for
drugs, in the fibre optics industry and for advanced coatings [1,6–
character (vinyloxyethane: Q = 0.018, e = ꢀ1.80) [4], vinyl ether do
copolymerise easily with fluoroolefins and lead to near perfect
alternating copolymers. Alternating copolymers schematically
form via two possible mechanisms: (i) the monomers are free
and add one after the other on the growing chain which reactivity
depends on the last (or last two) monomer(s) added [20,21]. (ii)
Charge transfer complexes are formed between electron-donating
and electron-attracting monomers, and these complexes add to the
growing polymer chain [22–26]. In the case of CTFE and vinyl ether,
Boutevin et al. have suggested that charge transfer complexes do
form readily, but that the copolymerisation proceeds via a free
monomer mechanism [5,27]. Copolymers of CTFE and vinyl ethers
are thus very interesting for their alternating structure and their
easy functionalisation (thanks to the wide range of existing
functional vinyl ethers). These copolymers are very useful for high
8
]. However, PCTFE is very insoluble in most organic solvents due
to his high crystallinity (Mp = 214–220 8C) and is difficult to
crosslink [9]. On the contrary, fluoropolymers based on vinyl
ethers are easy to crosslink and functionalise. Functional vinyl
ethers can be synthesised via transetherification [9–14]. Vinyl
ethers are usually polymerised by cationic polymerisation using
1
performance paints and coatings [17,28–34]. Lumiflon trade-
name, for example, are commercially available paints and coatings
based on poly(CTFE-alt-VE) copolymers marketed by Asahi Glass
Co. Ltd. [35–39]. In addition to these materials, poly(CTFE-alt-VE)
copolymers have attracted interests for applications in the domain
of energy, in particular in fuel-cells [40–42], in lithium-ion
batteries [43], and in photovoltaic applications [44].
either HI/I
2
[15] or triflic acid/tetrahydrothiophene [16]. It is
generally accepted that vinyl ethers do not homopolymerise under
radical polymerisation conditions [17], although a few reports
have shown that such homopolymerisation is indeed possible
Typically, functional copolymers can be prepared by (i)
direct copolymerisation of functional monomers; or by (ii)
[
18,19]. However, owing to their pronounced electron-donating
Scheme 2. Synthesis routes of the preparation of cyclocarbonate-containing poly(CTFE-alt-CCEV) copolymer.
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2. Results and discussion
Scheme 1 presents the general strategy to prepare the
poly(CTFE-alt-VE) copolymers carrying quaternary ammonium
groups without hydrogen atoms in position. A cyclocarbonate-
b
functionalised poly(CTFE-alt-VE) copolymer is first reacted with a
suitable primary amine bearing dimethylamino groups. In a second
step, the tertiary amines are quaternised using methyl iodide.
Cyclocarbonate-functionalised poly(CTFE-alt-VE) copolymers
can be obtained via 2 routes: (1) the copolymerisation of CTFE with
a cyclocarbonate-functionalised vinyl ether (Route A, Scheme 2)
and (2) the carbonation of a preformed copolymer carrying
epoxide moieties (Route B, Scheme 2). Both routes were examined.
2.1. Syntheses of the functional monomers: Vinyloxy-2-methyloxiran
(
GcEV) vinyloxy-4-methyl-1,3-dioxolan-2-one (CCEV)
GcEV was first prepared by transetherification of vinylox-
1
Fig. 1. H NMR of vinyloxy-2-methyloxirane (GcEV) recorded in acetone-d
6
. The red
yethane with glycidol in the presence of palladium acetate and
1,10-phenantroline [43(a)]. The reaction yield (63%) was relatively
good after vacuum distillation. GcEV monomer was obtained in
high purity (92%) (Fig. 1) as a racemic mixture of two isomers
(Fig. 2). Residual glycidol could not be completely eliminated by
distillation, but since glycidol is inert in the conditions of
polymerisation, GCEV was not further purified.
The cyclocarbonate-containing vinyl ether (CCEV) was synthe-
sised by carbonation of vinyloxy-2-methyloxiran (GcEV) as shown
in Scheme 2 (Route A). The carbonation reaction was performed
using the protocol designed by Endo et al. [51] (Fig. 3) by reaction
arrow indicates residual glycidol. (For interpretation of the references to colour in
this figure legend, the reader is referred to the web version of this article.)
post-polymerisation functionalisation of copolymers. The post-
polymerisation route was used successfully to prepare copolymers
bearing azoles [42,45] and phosphonic acids [46] for applications in
fuel-cell membrane, from copolymers of CTFE and vinyloxy-2-
chloroethane (CEVE). Similarly, Valade et al. [40] prepared
electrodes binders carrying quaternary ammonium groups by
nucleophilic substitution. These polymers however, presented
hydrogen atoms in
b position of the ammonium groups and were
thus sensitive to Hofmann degradation [47]. This problem was
partly circumvented using ATRP to prepare polystyrene grafts from
poly(CTFE-alt-CEVE) which were subsequently chloromethylated
and quaternised using trimethylamine [48]. To the best of our
knowledge, thereisonlyone reportedexample of poly(CTFE-alt-VE)
copolymer bearing Hofmannn degradation insensitive ammonium
groups [49].
The present article reports novel alternative methods to prepare
poly(CTFE-alt-VE) copolymers bearing Hofmann elimination insen-
sitive quaternary ammonium groups. CTFE was chosen for its high
resistance to alkaline medium, while functional VEs were used to
introduce functional groups into the copolymer backbone. Cyclo-
carbonate-functionalised poly(CTFE-alt-VE) copolymers were
synthesised via two routes and subsequently functionalised with
2
of CO in DMF in the presence of LiBr. The reaction was very
efficient, and a very pure cyclocarbonate vinyl ether (CCEV) was
obtained in high yields (97%) (Figs. S1 and S2).
2.2. Radical copolymerisation of CTFE with CCEV and with GcEV
The copolymerisation of CTFE and CCEV was carried out in
dimethylcarbonate at 74 8C using tert-butyl peroxypivalate as
initiator. After precipitation, the poly(CTFE-alt-CCEV) copolymer
1
19
was isolated in high yield (71%) and characterised by H and
F
NMR (Fig. 4) and SEC-HPLC (Table 1, entry 2). The NMR spectra
indicate a deviation from perfect alternating structure with signals
1
9
between ꢀ126 and ꢀ130 ppm in the F NMR spectrum assigned to
CFCl groups in CTFE-CTFE dyads [52]. These defects were also
detected by calculation of the copolymer composition (from
elemental analysis data, see supplementary info) which shows an
excess of CTFE (Table 1, entry 2). Importantly, the peaks of the CH
quaternary ammonium groups without hydrogen atoms in
b
position. Such copolymers if they proved to be sufficiently resistant
to alkaline medium may be very interesting to design original
membranes for solid alkaline fuel-cells (SAFC) [50].
2
and of the CH of the cyclocarbonate at 5.05 ppm and between
0
0
Fig. 2. Isomers of vinyloxy-2-methyloxirane (GcEV). Coupling constants for protons d, d and e (1/) and for protons f, f and e (2/).
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Fig. 3. Mechanism of the carbonation of epoxydes as proposed by Kihara et al. [51]. MX represents an alkaline metal salt (e.g. NaI, LiBr, LiCl,. . .).
1
19
6
Fig. 4. (a) H NMR spectrum and (b) F NMR spectrum of poly(CTFE-alt-CCEV) copolymer, recorded in acetone-d .
4
.3 and 4.7 ppm, respectively are still present and the intensity of
2.3. Carbonation of poly(CTFE-alt-GcEV) copolymer
their integration indicates that the cyclocarbonate rings were not
1
opened during the polymerisation. In addition, the H NMR
The carbonation of the poly(CTFE-alt-GcEV) copolymer was
performed using the conditions used for the carbonation of GcEV
monomer. The resulting copolymer was isolated by precipitation
from cold methanol, dried and characterised by H, F NMR, SEC-
HPLC, DSC, and TGA (Table 2.). This copolymer will be further
spectrum did not display any signals between 6.1 and 6.7 ppm,
ascribed to end-groups formed via transfer reactions (–CF
and CFCl–CF H) as suggested by Kumar et al. [53]. This copolymer
is further referred to as poly(CTFE-alt-CCEV)
2
–CFClH
1
19
2
A
.
The radical copolymerisation of CTFE and GcEV was carried out
under the same conditions and the corresponding copolymer was
also isolated with high yields (69%). Contrarily to poly(CTFE-alt-
CCEV) copolymer, poly(CTFE-alt-GcEV) copolymer contained very
few CTFE-CTFE dyads (Fig. 5) and the copolymer composition
calculated from elemental analysis did not show any excess of
CTFE in the copolymer (Table 1, entry 2). The epoxide rings were
also left intact during the polymerisation as indicated by the
presence of the expected signals of the epoxide ring between 2.5
and 3.3 ppm (Fig. 5).
referred to as poly(CTFE-alt-CCEV)
B
.
Both poly(CTFE-alt-CCEV) and poly(CTFE-alt-CCEV) copolymers
A
B
19
showed almost identical F NMR spectra with a slight presence of
1
signals assigned to CFCl groups in CTFE-CTFE dyads. The H NMR
spectra (Fig. S3) were also quite similar but in the case of poly(CTFE-
B
alt-CCEV) copolymer, small signals between 3.5 and 4 ppm attributed
to the presence of unreacted epoxide groups can be observed.
Overall, both preparation routes led to very similar polymers
and are thus both usable. Route A, the direct copolymerisation of
CTFE with CCEV, produces a copolymer with lower molecular
Table 1
Experimental conditions for the copolymerisations of CTFE and functional cyclic vinyl ethers.
b
Entry
VE
Feed
Solvent
Initiator
Yield (%)
Polymer
‘Mn (g/mol)
PDI
a
composition
composition
CTFE
VE
CTFE
VE
1
2
GcEV
CCEV
60
60
40
40
DMC
DMC
TBPPI
TBPPI
69
71
51.5
63.8
48.5
36.2
13,500
9600
2.2
1.5
Abbreviations: GcEV = vinyloxy-2-methyloxiran, CCEV = vinyloxy-4-methyl-1,3-dioxolan-2-one, DMC = dimethylcarbonate, TBPPI = tert-butyl peroxypivalate.
a
Calculated from elemental analysis (see Table S1 in Supplementary information).
b
Measured by SEC-HPLC using PS calibration standards.
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1
19
Fig. 5. (a) H NMR spectrum and (b) F NMR spectrum in acetone-d
6
of poly(CTFE-alt-GcEV) copolymer.
exhibited
poly(CTFE-alt-CCEV)
a
slightly lower decomposition temperature than
copolymer although their glass transition
temperatures were identical (Table 2).
Table 2
A
SEC-HPLC data and thermal properties of the resulting poly(CTFE-alt-CCEV)
copolymers.
2.3.1. Functionalisation of poly(CTFE-alt-CCEV) copolymer using the
Route
Yield (%)
Mn (g/mol)
PDI
T
g
(8C)
Td,10% (8C)
amine ring-opening of cyclocarbonate reaction
A
B
71
69
9600
1.5
1.5
35
35
307
271
Cyclocarbonates are known to react with nucleophiles [54]. The
reaction with amines is one of the best known example of these
ring-opening reaction and leads to the formation of hydroxyur-
ethane. This reaction which can be catalysed by tertiary amines
such as triethylamine (Scheme 3) [55] usually leads to the
formation of two isomers, one isomer bearing a secondary alcohol
(major product) and one isomer bearing a primary alcohol (minor
product). The goal here was to use this reaction to functionalise
poly(CTFE-alt-CCEV) copolymers and introduce tertiary amine into
the polymer. N,N,2,2-tetramethylpropane-1,3-diamine was used
13,500
weight and with an imperfect alternating structure, while Route B,
the carbonation of the epoxide-containing copolymer, yields a
higher molecular weight-copolymer with a more regular alternat-
ing structure. However, it was obtained in lower yield (due to the
loss during precipitation) and with a slightly lower number of
cyclocarbonate functions. Poly(CTFE-alt-CCEV)
B
copolymer also
Scheme 3. Mechanism of the reaction of cyclocarbonate ring-opening by amines, catalysed by triethylamine [55].
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Table 3
Experimental conditions of the amine-poly(CTFE-alt-CCEV) reaction.
Entry
Solvent
T (8C)
Duration (h)
[carbonate]
o
/[amine]
o
Catalyst (mol%)
Yield (mol%)
1
2
DMF
DMF
80
80
24
48
1.00:1.05
1.00:1.50
2
6
43
41
as it is non sensitive to Hofmann degradation thanks to its two
methyl groups, should be very reactive via its primary amine
function and could later be quaternised by methylation of its
dimethylamino group.
Two reactions between N,N,2,2-tetramethylpropane-1,3-di-
amine and poly(CTFE-alt-CCEV) were carried out in DMF at
80 8C in the presence of catalyst (TEA) (Table 3) and yielded the
amino-containing poly(CTFE-alt-UrEV) copolymer [56].
When a ratio of amine/carbonate of 1.05 was used, the reaction
was not complete. IR spectrometry (Fig. 6) showed that the peak of
ꢀ
1
the carbonyl of the cyclocarbonate at 1786 cm
significantly
decreased, but was still present in the polymer. The formation of
hydroxyurethane was nonetheless confirmed by the presence of
new peaks characteristic of the –CH
2
and CH
3
1
of N,N,2,2-
ꢀ
tetramethylpropane-1,3-diamine (1300–1600 cm
and 2700–
ꢀ1
ꢀ1
3
000 cm ), of the O–H and N–H bonds (3100–3700 cm ) and
Fig. 6. FTIR transmittance spectra of poly(CTFE-alt-CCEV) (blue), poly(CTFE-alt-
UrEV) (entry 1, Table 6, red), and poly(CTFE-alt-UrEV) (entry 2, Table 6, green). (For
interpretation of the references to colour in this figure legend, the reader is referred
to the web version of this article.)
ꢀ1
of the carbonyl of the urethane at 1698 cm . The introduction of
amine groups and the formation of hydroxyurethane were also
1
confirmed by H NMR (Fig. 7) which showed new signals at
1
Fig. 7. (a) Scheme of the cyclocarbonate ring-opening reaction of poly(CTFE-alt-CCEV) copolymer by N,N,2,2-tetramethylpropane-1,3-diamine. (b) H NMR spectrum in
1
6 6
acetone-d of the resulting poly(CTFE-alt-UrEV) copolymer. (c) H NMR spectrum in acetone-d of the precursor poly(CTFE-alt-CCEV) copolymer.
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Fig. 8. Mechanism for the degradation by basic hydrolysis of primary (1/) and secondary (2/) urethanes as proposed by Larson and Weber [59]. R
1
and R
2
represent alkyl or aryl
groups.
0
.9 ppm and between 2.1 and 2.5 ppm for the –C(CH
N(CH , respectively, and at 3.1 and 6.5 ppm for the –CH
and –CH –NH– of the urethane functions, respectively. It was
3
)
2
and –
observed (Figs. S4 and S5). No new signals corresponding to the
methylation of the urethane linkages could be seen. As expected,
iodomethane alone cannot methylate the carbamate groups. The
copolymers obtained were water-soluble and even though they
probably are non-sensitive to the Hofmann degradation, they may
not be resistant to very alkaline medium (due to the alkaline
sensitive urethane linkages). Films could be obtained from the
quaternised copolymers. However, these films were very brittle
presumably because of the low molecular weight of the
copolymers. Studies to solve these problems are underway and
will be reported in due course.
3
)
2
2
–NH–
2
nonetheless not possible to determine the ratio of the different
isomers or the actual extent of the ring-opening reaction.
Increasing the amount of amine and the reaction time did improve
the conversion, but still did not afford quantitative conversion of
the cyclocarbonates.
Urethane linkages can be hydrolysed in alkaline medium [57]
(
Fig. 8), which could be a problem for applications (including in
alkaline fuel cells). However, Kalinina et al.[58] did not observe
degradation of N-phenylmaleimide/cyclocarbonate-bearing vinyl
ether copolymers cross-linked via hydroxyurethane linkages after
3. Conclusions
3
h at 150 8C in concentrated sodium hydroxide solutions. Mabey
and Mill [59] reported a very different stability between primary
and secondary carbamates. While primary carbamates can be
hydrolysed very quickly without heating, secondary carbamates
can be strongly stabilised depending on the substituents present
on the nitrogen atom [59] (Table 4). Electron-donating methyl
group, for example, can considerably stabilise carbamates.
The preparation of functional fluoropolymers is a challenge to
synthetic chemist owing to the scarcity of commercially available
functional fluoroolefins. This article demonstrates that alternating
copolymerisation of CTFE and functional vinyl ether is a very efficient
way to prepare highly functional fluorinated copolymers. The goal
was to prepare copolymers bearing Hofmann elimination insensitive
quaternary ammonium groups from cyclocarbonate-containing
copolymers using the cyclocarbonate amine reaction. Two functional
vinyl ethers, GcEV (epoxide-containing) and CCEV (cyclocarbonate-
containing) monomers were synthesised in high yields an purity and
copolymerised with CTFE. The copolymerisation of GcEV and CTFE
led to a nearly perfect alternating copolymer whereas that of CCEV
and CTFE led to copolymer with structural defects (CTFE–CTFE
dyads). Both the epoxides and cyclocarbonates functional groups
seemed unaffected by the polymerisation conditions. The carbon-
ation of the poly(CTFE-alt-GcEV) proceeded with near quantitative
yield. The ring-opening of the cyclocarbonates with N,N,2,2-
tetramethylpropane-1,3-diamine was relatively efficient and yielded
a suitable amine-functionalised copolymer which could be easily
quaternised without side reactions using iodomethane. More work is
required however to prepare non water-soluble higher molecular
weight copolymers. The combination of this donor–acceptor
copolymerisation and the ring-opening of cyclocarbonates by amine
is a very promising synthetic method to introduce a range of
functional groups onto a copolymeric backbone.
Methylation of carbamates are usually performed using
a
combination of iodomethane and a strong base such as sodium
hydride or lithium bis(trimethylsilyl)amide [60–62]. In this work
however, to avoid side reactions, mild conditions (absence of
strong base) were used for the methylation reaction. The
poly(CTFE-alt-UrEV) copolymer was dissolved in acetone and
iodomethane was added to the solution. After purification, a water-
1
13
soluble material was isolated in high yields (85%). H NMR and
NMR (DEPT 135 experiment) spectra (Figs. S4 and S5, respectively)
showed the complete shift of the signals of the –CH –N(CH
C
2
3 2
)
groups upon quaternisation. Indeed, the complete disappearance
1
of peaks between 2.0 and 2.5 ppm in H NMR, and at 48.6 and
1
3
6
9.5 ppm in C NMR due to N(CH
3 2 2 3 2
) and –CH –N(CH ) ), and the
1
formation of new peaks between 3.0 and 3.5 ppm in H NMR and at
5.9 and 73.7 ppm in C NMR caused by –CH
13
+
5
2
–N(CH
3
)
3
are
Table 4
Half-life of various carbamates under hydrolytic conditions at pH = 7 and T = 25 8C
calculated by Mabey and Mill [3]. R , R and R represent the groups connected to
the carbamates as indicated in Fig. 8.
1
2
3
R
3
R
1
R
2
t
1/2
4. Experimental
C
C
6
H
H
5
5
C
C
C
C
6
6
6
6
H
H
H
H
5
5
5
5
H
1.5 days
5200 years
26 s
6
CH
3
4.1. Analyses
P-NO
P-NO
2
C
C
5
H
H
4
4
H
2
5
CH
3
2700 years
8.5 days
1200 years
1
13
19
NMR spectra H, C, and F were acquired using a Bruker AC
1
-C10
H
H
9
CH
CH
3
H
400 at 25 8C. FTIR analyses were performed in ATR mode using a
1
-C10
9
3
CH
3
Perkin-Elmer Spectrum 1000. SEC-HPLC analyses were performed
Please cite this article in press as: G. Couture, et al., J. Fluorine Chem. (2014), http://dx.doi.org/10.1016/j.jfluchem.2014.08.014

G Model
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8
G. Couture et al. / Journal of Fluorine Chemistry xxx (2014) xxx–xxx
on a Polymer Laboratories PL-GPC 50 instrument using 2 PL Mixed
C 5 m columns thermostated at 35 8C, THF as eluent (1.0 mL/min)
heated at 80 8C for 16 h. The reactor was then cooled down and the
gases were evacuated. DMF was removed under reduced pressure.
50 mL of dichloromethane were added and the organic solution
was washed with deionised water (3 ꢁ 30 mL). The aqueous
phases were extracted once with dichloromethane (20 mL). The
m
and a refractive index detector. Calibration was done using Varian
polystyrene narrow standards. Elemental analyses were per-
formed by the Service central d’Analyses of CNRS (Villeurbanne,
France). TGA analyses were performed on 10–15 mg samples on a
TGA 51 instrument (TA Instruments) from 20 8C to 700 8C using a
4
organic phase was dried with MgSO and the solvent was removed
under reduced pressure. The product was isolated as a brown
liquid.
2
0 8C/min heating ramp under air flow. DSC measurements were
performed on 15 mg samples on a Perkin-Elmer Pyris 1 instrument
using the following heating/cooling cycle: Heating from ꢀ50 8C to
Vinyloxy-4-methyl-1,3-dioxolan-2-one (CCEV)
1
+
150 8C at 20 8C/min, isotherm plateau at 150 8C for 3 min, cooling
H NMR (Acetone-d
6
)
d
(ppm): 3.97 (dd, –CHH–OCOO–,
2
2
2
2
3
from 150 8C to ꢀ50 8C at 20 8C/min, isotherm plateau at ꢀ50 8C for
J
J
J
J
gem = 11.75 Hz,
gem = 11.87 Hz, trans = 2.78, 1H), 4.06 (dd, CHH–CH 55 (E),
gem = 2.27 Hz, Jcis = 6.82 Hz, 1H), 4.29 (dd, CHH–CH 55 (Z),
Jtrans = 4.17, 1H), 4.05 (dd, –CHH–OCOO–,
3
3
min. The heating/cooling cycle was performed twice per sample.
were measured at the inflexion point of the enthalpic jump.
J
3
T
g
3
gem = 2.27 Hz, Jtrans = 14.27 Hz, 1H), 4.40 (dd, –O–CHH–Carbon-
2
3
4.2. Chemicals
ate,
Jgem = 8.46 Hz, Jtrans = 5.94 Hz, 1H), 4.65 (dd (t), –O–CHH–
2
3
Carbonate, Jgem = 8.59 Hz, Jcis = 8.59 Hz, 1H), 5.09 (m, –CH
2
–CH<,
Jtrans = 14.27 Hz,
3
3
N,N,2,2-tetramethylpropane-1,3-diamine, palladium acetate
1H), 6.55 (ddt, CH
2
–CH 55 ,
J
cis = 6.82 Hz,
4
and iodomethane were purchased from ABCR. Glycidol, vinylox-
yethane, 1,10-phenanthroline, and all the solvents were purchased
from Sigma-Aldrich. Chlorotrifluoroethylene was provided by
Honeywell (Buffalo, NY, USA). Tert-butylperoxypivalate was
provided by AkzoNobel (Compi e` gne, France). Deuterated solvents
for NMR were purchased from Euroiso-top. All chemicals and
solvents were used as received unless otherwise noted.
J = 0.51 Hz, 1H).
1
3
C NMR (Acetone-d
68.2 (–O–CH –CH<, 1C), 75.5 (–CH
1C), 152.2 (–CH 55 CH , 1C), 206.3 (>C 55 O, 1C).
6
)
d
(ppm): 66.7 (>HC–CH
2
–carbonate, 1C),
C 55 CHO–,
2
2
–CH<, 1C), 88.0 (H
2
2
4.4. Radical copolymerisation of CTFE with vinyl ethers
All the copolymerisations were carried out using 100 or 300 mL
Parr pressure reactors fitted with a rupture disc (3000 psi),
mechanical stirring system, a manometer and 2 injection valves.
Before reaction, all the solids are placed in the reactor which is then
first filled with 20 bar of nitrogen (to detect leaks) and then put
4
4
.3. Vinyl ether synthesis
.3.1. Vinyloxy-2-methyloxiranne (GcEV)
Palladium acetate (34.42 mg, 1.52 mmol) and 1,10 phenan-
ꢀ
2
troline (41.2 mg, 2.29 mmol) were dissolved separately in 10 mL
under vacuum (10 mbar) for 2 h. The liquid phases (initiators,
liquid monomers, solvent) are first degassed by argon or nitrogen
bubbling and then introduced into the reactor via a funnel. The
desired amount of CTFE is then transferred in the reactor using
double weighing method. The reaction mixture is then heated up
to the desired temperature under stirring for the required time. At
the end of the reaction, the reactor is cooled down to ambient
temperature, the remaining gases are evacuated, and the resulting
residue is dissolved into acetone, concentrated under vacuum and
precipitated in cold methanol. The polymer is then dried under
vacuum (10 mbar) at 60 8C for 12 h. In a typical reaction, 33.5 g
(0.288 mol) of CTFE was added to a Parr pressure reactor
containing 20.0 g (0.188 mol) of CEVE, 81.9 mg (4.70 mmol) of
TBPPI, 75.5 mg (5.46 mmol) of potassium carbonate and 150 mL of
1,1,1,3,3-pentafluorobutane. The reactor was then heated up to
74 8C for 16 h. The polymer was then precipitated and dried as
described above.
of dichloromethane and mixed together at 20 8C for 15 min.
2
0.00 g (269.99 mmol) of glycidol and 263.00 g (2.29 mol) of
vinyloxyethane were placed along with the catalyst solution into
a pressure reactor. The reactor was closed and the reaction
mixture was heated under stirring at 60 8C for 48 h. The volatiles
were removed using a rotary evaporator. Diethyl ether was
added to the residue, and the precipitated catalyst was filtered
off. 17.03 g (170.09 mmol) of GcEV was then isolated by
distillation under reduced pressure and obtained as a transpar-
ent colourless liquid.
1
H NMR (Acetone-d
6
)
d
3 2
(ppm): 0.89 (s, C–CH , 6H), 2.15 (s, –CH –
N, 2H), 2.23 (s, N–CH
3
, 6H), 3.44 (s, –CH –O, 2H), 3.91 (dd, CHH–
2
2
3
CH 55 (E), Jgem = 1.77 Hz, Jcis = 6.82 Hz, 1H), 4.16 (dd, CHH–CH 55 (Z),
2
3
J
gem = 1.64 Hz,
2
Jtrans = 14.27 Hz, 1H), 6.51 (ddt, CH –CH 55 ,
3
3
4
J
cis = 6.82 Hz, Jtrans = 14.27 Hz, J = 0.51 Hz, 1H).
1
3
C NMR (Acetone-d
–C<, 1C), 48.8 (CH
–O, 1C), 86.2 (H C 55 CH, 1C), 153.1 (H
H NMR (Acetone-d (ppm): 2.61 (dd, –CHH–O– epoxy,
trans = 2.53, 1H), 2.77 (dd, –CHH–O– epoxy,
6
)
d
(ppm): 23.5 (CH
–N, 2C), 67.2 (CH
C 55 CH, 1C).
3
–C, 2C), 37.1
–N, 1C), 74.7
(
(
(CH
CH
3
)
2
3
2
2
2
2
4.5. Carbonation of poly(CTFE-alt-GcEV) copolymer
1
6
) d
2
2
3
J
J
gem = 5.05 Hz,
gem = 5.05 Hz,
J
J
Poly(CTFE-alt-GcEV) copolymer (2.005 g, 9.24 mmol) and LiBr
(0.041 g, 0.46 mmol) were dissolved in 30 mL of DMF in a 50 mL
3
cis = 4.17 Hz, 1H), 3.17 (m, –CH
2
–CH<, 1H),
cis = 6.32 Hz, 1H), 3.99
dd, CHH–CH = (E), Jgem = 2.02 Hz, Jcis = 6.82 Hz, 1H), 4.01 (dd, –
2
3
3
(
.56 (dd, –O–CHH–,
J
gem = 11.62 Hz,
J
Parr pressure reactor. The reactor was closed and 15 bar of CO
2
2
3
were introduced. The reaction mixture was then heated at 80 8C for
16 h. Gas in excess was then evacuated and the copolymer was
precipitated in cold methanol. The solid was dried at 60 8C under
vacuum for 12 h.
2
3
O–CHH–,
J
gem = 11.62 Hz,
Jtrans = 2.78 Hz, 1H), 4.22 (dd, CHH–
2
3
CH = (Z),
J
gem = 2.02 Hz,
J
trans = 14.27 Hz, 1H), 6.50 (ddt, CH
2
–
3
3
4
CH 55 , Jcis = 6.82 Hz, Jtrans = 14.27 Hz, J = 0.51 Hz, 1H).
1
3
C NMR (Acetone-d
–CH<, 1C), 70.1 (>HC–CH
52.6 (>C 55 CH , 1C).
6
)
d
(ppm): 44.2 (CH–CH
2
–O–, 1C), 50.3 (–
C 55 CHO–, 1C),
CH
1
2
2
–O–, 1C), 87.4 (H
2
4.6. Functionalisation of poly(CTFE-alt-CCEV) copolymer by
carbonate/amine reaction
2
4
.3.2. Carbonation of vinyloxy-2-methyloxirane
1.006 g (3.84 mmol) of poly(CTFE-alt-CCEV) copolymer, dissolved
in 20 mL of DMF, were placed into a 50 mL round bottom flask.
N,N,2,2-tetramethylpropane-1,3-diamine (0.750 g, 5.76 mmol), and
triethylamine (0.023 g, 0.23 mmol) were added to the DMF solution,
and the reaction mixture was heated under stirring at 80 8C for 48 h.
5
.003 g (50.0 mmol) of vinyloxy-2-methyloxiran and lithium
bromide (21.7 mg, 2.50 mmol) were dissolved into 30 mL of DMF
and place into a Parr pressure reactor. The reactor was closed and
1
2
5 bar of CO were introduced. The reaction mixture was then
Please cite this article in press as: G. Couture, et al., J. Fluorine Chem. (2014), http://dx.doi.org/10.1016/j.jfluchem.2014.08.014

G Model
FLUOR-8406; No. of Pages 9
G. Couture et al. / Journal of Fluorine Chemistry xxx (2014) xxx–xxx
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Please cite this article in press as: G. Couture, et al., J. Fluorine Chem. (2014), http://dx.doi.org/10.1016/j.jfluchem.2014.08.014