COPOLYMERS CONTAINING VINYLIDENE FLUORIDE AND
TRIFLUOROETHYLENE
FIELD OF THE INVENTION
5 The present invention relates to copolymers based on vinylidene
fluoride (VDF), on trifluoroethylene (TrFE) and on at least one third monomer,
and also to a process for the preparation of these copolymers.
TECHNICAL BACKGROUND
10 Fluoropolymers represent a class of compounds having noteworthy
properties for a large number of applications, from paint or special coatings to
leaktight seals, via the intermediacy of optics, microelectronics and
membrane technology. Among these fluoropolymers, copolymers are
particularly advantageous due to their diversity, their morphology, their
15 exceptional properties and their versatility.
The paper by Yagi et al. in Polymer Journal, 6, 429-436 (1979),
describes a conventional copolymerization of vinylidene fluoride with
trifluoroethylene. These copolymers exhibit particularly advantageous
piezoelectric properties, as is discussed in the paper by Higashihata et al. in
20 Ferroelectrics, 2, 85-92 (1981).
The papers by Wang et al. in Macromolecules, 39, 4268-4271 (2006),
by Lu et al. in Macromolecules, 39, 6962-6968 (2006), by Lu et al. in J. Am.
Chem. Soc, 128, 8120-8121 (2006), and by Zhang et al. in Macromolecules,
40, 783-785 (2007), describe a process for the preparation of terpolymers of
25 vinylidene fluoride, of trifluoroethylene and of chlorotrifluoroethylene (CTFE)
by a copolymerization of vinylidene fluoride with CTFE, followed by a
reduction of the chlorine atoms of the CTFE units.
Furthermore, controlled radical copolymerization techniques, that is to
say techniques which make it possible to obtain control of the molar mass
30 and the polydispersity index of the polymers, have also been provided.
The document US 6 355 749 describes the preparation of terpolymers
of vinylidene fluoride, of trifluoroethylene and of a comonomer, such as CTFE
or HFP, according to a process of copolymerization controlled by means of
borane compounds in the presence of oxygen. Likewise, the paper by Chung
35 et al. in Macromolecules, 35, 7678-7684 (2002), describes the manufacture
of terpolymers of vinylidene fluoride, of trifluoroethylene and of a chlorinated
comonomer (CTFE, CDFE or 2-chloro-1,1 -trifluoroethylene, VC or vinyl
WO 2014/162080 2 PCT/FR2014/050721
chloride, CFE or 1,1-chlorofluoroethylene), also according to a
copolymerization controlled by means of borane compounds. A fluorinated
comonomer (VF or vinyl fluoride, HFP) is also used byway of reference. This
technique is difficult to carry out in practice due to the high cost of the borane
5 compounds and the risks of explosion which they bring about.
Other methods of controlled radical copolymerization are based on the
use of xanthate compounds as chain-transfer agents, under the name
MADIX, for "Macromolecular Design via interchange of Xanthates", or also by
means of iodine compounds as chain-transfer agents.
10 Two reviews summarizing relevant studies in the field have been
published in Macromolecules, 43, 10163-10184 (2010), and in Chem. Rev.,
109,6632-6686(2009).
The document US 2008/0081195 describes terpolymers, such as
P(VDF-TrFE-CTFE) terpolymers, exhibiting two functional endings and
15 prepared by polymerization controlled by borane or diiodine transfer agents.
The paper by Li et al. in J. Appl. Polym. ScL, 122, 3007-3015 (2011),
describes the synthesis and the crystallization of P(VDF-TrFE-CTFE)
terpolymers.
The paper by Saint Loup et al. in Macromolecules, 35, 1524-1536
20 (2002), describes the copolymerization of VDF and HFP and also the
terpolymerization of VDF, HFP and CTFE initiated by hydrogen peroxide.
The properties of P(VDF-TrFE-CFE) and P(VDF-TrFE-CTFE)
terpolymers are explored in the papers by Xu et al. in Appl. Phys. Lett, 78,
2360-2362 (2001), by Jeong et al. in Appl. Phys. Lett., 85, 4857-4859 (2004),
25 by Claude et al. in Appl. Phys. Lett, 91, 212904 (2007), and by Claude et al.
in Chem. Mater, 20, 2078-2080 (2008).
The paper by Zhu et al. in Macromolecules, 45, 2937-2954 (2012),
describes the ferroelectric properties of several polymers of the
polyvinylidene fluoride (PVDF) family and in particular of
30 P(VDF-TrFE-CDFE), P(VDF-TrFE-CTFE), P(VDF-TrFE-HFP) and
P(VDF-TrFE-CFE) terpolymers.
However, there still exists a need to develop novel fluorinated
copolymers and in particular novel copolymers based on VDF and on TrFE.
35 SUMMARY OF THE INVENTION
The invention relates first to a copolymer obtained by copolymerization
of vinylidene fluoride, of trifluoroethylene and of at least one third monomer,
WO 2014/162080 3 PCT/FR2014/050721
said third monomer having a molar mass of greater than 100g/mol and
corresponding to the formula:
5 R1 R2
in which Ri represents a hydrogen atom or a fluorine atom and R2 and
R3 are chosen, independently of one another, from CI, F, CF3 and functional
groups selected from phosphonate, carboxylic acid, S02X (where X
represents F, OK, ONa or OH) or Si(OR)3 (R representing a methyl, ethyl or
10 isopropyl group) groups.
According to one embodiment, the third monomer is chosen from
2,3,3,3-tetrafluoropropene, 2-chloro-3,3,3-trifluoropropene, a,(3-difluoroacrylic
acid, 2-(trifluoro)methacrylic acid, dimethyl vinylphosphonate,
bromotrifluoroethylene, vinyl trifluoroacetate, itaconic acid and t-butyl 2-
15 (trifluoromethyl)acrylate.
According to one embodiment:
- the molar proportion of units resulting from the vinylidene fluoride
monomer is from 40 to 90% and preferably from 55 to 80%;
- the molar proportion of units resulting from the trifluoroethylene
20 monomer is from 5 to 50% and preferably from 10 to 40%; and
- the molar proportion of units resulting from at least one third
monomer is from 1 to 20% and preferably from 2 to 18%.
Another subject matter of the invention is a process for the preparation
of a copolymer comprising a stage of copolymerization of a reaction mixture
25 of vinylidene fluoride, of trifluoroethylene and of at least one third monomer
having a molar mass of greater than 100g/mol, the third monomer
corresponding to the formula:
30 R1 R2
in which R1 represents a hydrogen atom or a fluorine atom and R2 and
R3 are chosen, independently of one another, from CI, F, CF3 and functional
groups selected from phosphonate, carboxylic acid, S02X (where X
represents F, OK, ONa or OH) or Si(OR)3 (R representing a methyl, ethyl or
35 isopropyl group) groups.
According to one embodiment, the third monomer is chosen from
2,3,3,3-tetrafluoropropene (or 1234yf), 2-ch!oro-3,3,3-trifluoropropene, a,pa
WO 2014/162080 4 PCT/FR2014/050721
difluoroacrylic acid, 2-(trifluoro)methacryliciacid, dimethyl vinylphosphonate,
bromotrifluoroethylene, vinyl trifluoroacetate, itaconic acid and t-butyl 2-
(trifluoromethyl)acrylate.
According to one embodiment:
5 - the molar proportion of vinylidene fluoride in the reaction mixture is
from 40 to 90% and preferably from 55 to 80%;
- the molar proportion of trifluoroethylene in the reaction mixture is
from 5 to 50% and preferably from 10 to 40%; and
- the molar proportion of the third monomer(s) in the reaction
10 mixture is from 1 to 20% and preferably from 2 to 18%;
the molar proportions being with respect to the sum of the vinylidene
fluoride, trifluoroethylene and third monomer.
According to one embodiment, the reaction mixture is devoid of chaintransfer
agent.
15 According to one embodiment, the reaction mixture essentially
comprises and preferably consists of a mixture of vinylidene fluoride, of
trifluoroethylene, of at least one third monomer, of radical initiator and of
solvent and/or of water.
According to one embodiment, the reaction mixture is heated up to a
20 temperature for initiation of reaction of between 60 and 90°C, preferably
between 70 and 80°C and more preferably between 72 and 76°C.
According to one embodiment, the copolymer described above is
prepared by the abovementioned process.
Another subject matter of the invention is a film or a membrane
25 comprising at least one copolymer as described above.
Another subject matter of the invention is a piezoelectric device
comprising such a film.
Another subject matter of the invention is a ferroelectric device
comprising such a film.
30 Another subject matter of the invention is a pyroelectric device
comprising such a film.
Another subject matter of the invention is a coating comprising such a
film.
The present invention makes it possible to meet the needs existing in
35 the state of the art.
The invention is of particular use for the manufacture of piezoelectric,
ferroelectric or pyroelectric compounds.
WO 2014/162080 5 PCT/FR2014/050721
BRIEF DESCRIPTION OF THE FIGURES
Figure 1a represents a 1HNMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-fer-TrFE-fer-1234yf) terpolymer (see example 1).
5 Figure 1b represents a 19F NMR spectrum of the same terpolymer in
de-acetone (20°C, 400 MHz).
Figure 2a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-ter-TrFE-feM234yf) terpolymer (see example 2).
Figure 2b represents a 19F NMR spectrum of the same terpolymer in
10 d6-acetone (20°C, 400 MHz).
Figure 3a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-ter-TrFE-ter-1234yf) terpolymer (see example 3).
Figure 3b represents a 19F NMR spectrum of the same terpolymer in
de-acetone (20°C, 400 MHz).
15 Figure 4a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-fer-TrFE-fer-1234yf) terpolymer (see example 4).
Figure 4b represents a 19F NMR spectrum of the same terpolymer in
de-acetone (20°C, 400 MHz).
Figure 5a represents a 1H NMR spectrum in d6-acetone (20°C,
20 400 MHz) of a poly(VDF-ter-TrFE-ter-1234yf) terpolymer (see example 5).
Figure 5b represents a 19F NMR spectrum of the same terpolymer in
de-acetone (20°C, 400 MHz).
Figure 6a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-ter-TrFE-fer-2-chloro-3,3,3-trifluoropropene)
2 5 terpolymer (see example 6).
Figure 6b represents a 19F NMR spectrum of the same terpolymer in
d6-acetone (20°C, 400 MHz).
Figure 7a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-ter-TrFE-ter-dimethyl vinylphosphonate) terpolymer
30 (see example 7).
Figure 7b represents a 19F NMR spectrum of the same terpolymer in
d6-acetone (20°C, 400 MHz).
Figure 8a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-fer-TrFE-feMtaconic acid) terpolymer (see
35 example 8).
Figure 8b represents a 19F NMR spectrum of the same terpolymer in
de-acetone (20°C, 400 MHz).
WO 2014/162080 6 PCT/FR2014/050721
Figure 9a represents a 1H NMR spectrum in d6-acetone (20°C,
400 MHz) of a poly(VDF-fer-TrFE-fer-a,p-difluoroacryiic acid) terpoiymer (see
example 9).
Figure 9b represents a 19F NMR spectrum of the same terpoiymer in
5 d6-acetone (20°C, 400 MHz).
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
The invention is now described in more detail and without implied
limitation in the description which follows.
10 The invention provides for the preparation of a copolymer by means of
a polymerization reaction between TrFE, VDF and at least one third
monomer.
The term "copolymer" means here a polymer resulting from the
copolymerization of at least three types of comonomers which are chemically
15 different. The third monomer, which is distinct from TrFE and VDF, exhibits a
molar mass of greater than 100 g/mol and corresponds to the formula:
20 in which Ri represents a hydrogen atom or a fluorine atom and R2 and
R3 are chosen, independently from one another, from CI, F, CF3 and
functional groups selected from phosphonate, carboxylic acid, SO2X (where
X represents F, OK, ONa or OH) or Si(OR)3 (R representing a methyl, ethyl
or isopropyl group) groups. "Functional group" is understood here to mean a
25 group of atoms comprising at least two atoms, at least one of which is other
than C and H.
According to one embodiment, the copolymers of the invention are
terpolymers consisting of three different comonomers.
According to another embodiment, the copolymer of the invention is
30 composed of four comonomers having distinct structures.
The copolymers according to the invention are random and linear.
Preferably, the third monomer exhibits a molar mass of less than or
equal to 150 g/mol and in particular less than or equal to 145 g/mol or less
than or equal to 140 g/mol.
35 According to one embodiment, the third monomer is chosen from
2,3,3,3-tetrafluoropropene (or 1234yf), 2-chloro-3,3,3-trifluoropropene, a,pdifluoroacrylic
acid, 2-(trifluoro)methacrylic acid, dimethyl vinylphosphonate,
WO 2014/162080 7 PCT/FR2014/050721
bromotrifluoroethylene, vinyl trifluoroacetate, itaconic acid and t-butyl 2-
(trifluoromethy!)acrylate.
The polymerization reaction is preferably conventional, in contrast to a
controlled radical polymerization, that is to say that the polymerization is
5 carried out without a chain-transfer agent.
"Chain-transfer agent is understood to mean a substance capable of
causing a chain transfer in the polymerization reaction. A chain transfer is a
transfer of the reactive radical at the end of the growing polymer chain to
another molecule. Xanthate, iodine or borane compounds are examples of
10 chain-transfer agents. Reference may be made to the work by Ameduri and
Boutevin entitled Well Architectured Fluoropolymers: Synthesis, Properties
and Applications, published by Elsevier, Amsterdam (2004).
The conventional polymerization reaction makes it possible in
particular to obtain larger polydispersity indices than controlled radical
15 polymerization.
The polymerization reaction is carried out in the presence of a radical
initiator. The latter can, for example, be tert-butyl peroxypivalate (or TBPPI),
tert-amyl peroxypivalate, bis(4-(ferf-butyl)cyclohexyl) peroxydicarbonate,
sodium, ammonium or potassium persulfate, benzoyl peroxide, tert-butyl
20 hydroperoxide, tert-butyl peroxide or 2,5-bis(tert-butylperoxy)-2,5-
dimethylhexane.
The reaction is carried out in a solvent which is, for example, chosen
from 1,1,1,3,3-pentafluorobutane, acetonitrile, methyl ethyl ketone, dimethyl
carbonate, 2,2,2-trifluoroethanol, hexafluoroisopropanol, methyl acetate,
25 ethyl acetate, cyclohexanone, water and the mixtures of these.
The reaction is preferably carried out at a temperature of 10 to 200°C,
preferably of 35 to 170°C, and at a pressure of 10 to 120 bar, preferably of
20 to 80 bar. The choice of the optimum temperature depends on the initiator
which is used. Generally, the reaction is carried out for at least 6 hours, at a
30 temperature at which the half-life of the initiator is approximately 1 hour.
A reaction temperature of between 60 and 90°C, preferably between
70 and 80°C and more particularly between 72 and 76°C is appropriate in
some embodiments.
According to a preferred embodiment, the molar proportion of VDF
35 units in the terpolymer is from 40 to 90%, preferably from 55 to 80%.
According to a preferred embodiment, the molar proportion of TrFE
units in the terpolymer is from 5 to 50%, preferably from 10 to 40%.
WO 2014/162080 8 PCT/FR2014/050721
10
According to a preferred embodiment, the molar proportion of units
resulting from the third monomer in the terpolymer is from 1 to 20%,
preferably from 2 to 18%.
The molar mass of the terpolymer obtained is preferably from 20 000
to 100 000 g/mol, more preferably from 20 000 to 80 000 g/mol. The higher
the molar mass, the better are the properties of the materials obtained.
The polydispersity index of the terpolymer obtained is preferably from
1.4 to 3.5, more preferably from 1.48 to 2.5.
The copolymers obtained according to the invention are of use in
particular in the manufacture of electrolytes or in the manufacture of
membranes. They are also of use in the manufacture of piezoelectric,
ferroelectric or pyroelectric devices and also of coatings.
15
EXAMPLES
The following examples illustrate the invention without limiting it.
20
Example 1 - Synthesis of polv(VDF-fer-TrFE-fer-1234yf) (VDF: 80%; TrFE:
15%; 1234vf: 5% - initial molar ratios)
The synthesis of the polymer poly(VDF-fer-TrFE-fer-1234yf) is carried
out according to the following scheme:
n C H i - C F j + )==( + H2C=CF
CF,
25
30
80% 15%
TBPPI
C4F5HS, 75flC
5%
F
/CH2-CF2}{cH2-C-)4-C/-CF5)- -
CFS H
The radical polymerization is carried out in a 100 ml Parr Hastelloy
35 autoclave equipped with a manometer, a bursting disc and valves for
. introducing gas and releasing. A regulated electronic device controls both the
3
WO 2014/162080 9 PCT/FR2014/050721
stirring and the heating of the autoclave. The reactor is pressurized to 30 bar
of nitrogen for 1 h in order to confirm the leaktightness thereof.
Once the nitrogen has been discharged, the reactor is placed under
vacuum for 40 min and then the radical initiator (TBPPI, 0.589 g, i.e.
5 3.38 mmol) and the solvent (60 ml of 1,1,1,3,3-pentafluorobutane) are
introduced. The reactor is subsequently cooled to -60°C (acetone/liquid
nitrogen mixture) and then the 1234yf (1.5 g, i.e. 0.02 mol), the TrFE (3 g, i.e.
0.038 mol) and the VDF (13.0 g, i.e. 0.203 mol) are successively introduced
therein.
10 The reactor is gradually heated to 74°C and the change in the
pressure and in the temperature are recorded. During the polymerization, an
increase in the pressure inside the reactor is observed, due to the
exothermicity of the reaction, and then a decrease in the pressure is
observed, brought about by the conversion of the gaseous fluorinated
15 monomers to give the desired terpolymer. At 74°C, the pressure is close to
34 bar (a rapid increase in the temperature after 78°C is observed). During
the hour which follows this exotherm, the pressure changes from 34 bar to
12 bar with a temperature maintained at 74°C.
After reaction and cooling, the reactor is left in ice for 30 min and then
20 vented (which makes possible the release of the unreacted fluorinated
monomers). After opening the reactor, the solvent is removed by distillation
and then the product is precipitated from cold pentane, filtered off,
redissolved in the minimum amount of acetone, reprecipitated, filtered off and
dried under vacuum (10"2bar, 60°C) to constant weight. The poly(VDF-ter-
25 TrFE-ter-1234yf) terpolymer, in the form of a white powder, is characterized
by 1H NMR spectroscopy (Figure 1a) and 19F NMR spectroscopy
(Figure 1b). The yield by weight (weight of terpolymer collected/sum of the
weights of the comonomers introduced into the reactor) is 62%.
30 Example 2 - Synthesis of polv(VDF-fer-TrFE-fer-1234vf) (VDF: 70%; TrFE:
25%: 1234vf: 5% - initial molar ratios)
The synthesis of the poly(VDF-fer-TrFE-fer-1234yf) polymer is carried
out according to the same protocol as in example 1.
In detail, the operation is carried out as above in a 100 ml HC-276
35 reactor by respectively introducing therein the TBPPI (0.672 g, i.e.
3.86 mmol) and 60 ml of 1,1,1,3,3-pentafluorobutane. The reactor is
subsequently cooled to -60°C (acetone/liquid nitrogen mixture) and then the
WO 2014/162080 10 PCT/FR2014/050721
1234yf (1.66g, i.e. 0.014 mol) and the TrFE (5.94 g, i.e. 0.072 mol), followed
by the VDF (13 g, i.e. 0.203 mol), are successively introduced therein.
The reactor is gradually heated to 74°C and the changes in the
pressure and in the temperature are recorded. During the polymerization, an
5 increase in the pressure inside the reactor is observed and then a decrease
in the pressure is observed, brought about by the conversion of the gaseous
fiuorinated monomers to give terpolymer. At 74°C, the pressure is close to
37 bar (exothermicity up to 76°C). During the hour following this exotherm,
the pressure falls to 13 .bar for a temperature maintained at 74°C.
10 As above, after reaction and cooling, the reactor is left in ice for 30 min
and then vented. After opening, the solvent is distilled off. The product is
precipitated from cold pentane, filtered off and dried under vacuum (10~2 bar,
60°C) for 14 hours. The poly(VDF-fer-TrFE-ter-1234yf) terpolymer, in the
form of a white powder, is characterized by 1H NMR spectroscopy (figure 2a)
15 and 19F NMR spectroscopy (figure 2b). The yield by weight is 88%.
Example 3 - Synthesis of poly(VDF-ter-TrFE-fer-1234vf) (VDF: 57%; TrFE:
33%: 1234vf: 10% - initial molar ratios)
The synthesis of the poly(VDF-ter-TrFE-fer-1234yf) polymer is carried
20 out according to the same protocol as in example 1.
In detail, the operation is carried out as above in a 100 ml HC-276
reactor by respectively introducing therein the TBPPI (0.689 g, i.e.
5.48 mmol) and 60 ml of 1,1,1,3,3-pentafluorobutane. The reactor is
subsequently cooled to -60°C (acetone/liquid nitrogen mixture) and then the
25 1234yf (5g, i.e. 0.043 mol) and the trifluoroethylene TrFE (11 g, i.e.
0.134 mol), followed by the VDF (15 g, i.e. 0.234 mol), are introduced therein.
The reactor is gradually heated to 74°C and, during the
polymerization, an increase in the pressure inside the reactor is observed,
due to the exothermicity of the reaction, and then a decrease in the pressure
30 is observed, brought about by the conversion of the gaseous fiuorinated
monomers to give the desired polymer. At 74°C, the pressure is close to
38 bar (exothermicity up to 76°C). During the hour following this exotherm,
the pressure falls to 17 bar for a temperature maintained at 74°C.
As above, after reaction and cooling, the reactor is left in ice for 30 min
35 and then vented. After opening, the solvent is distilled off. The product is
precipitated from cold pentane, filtered off, redissolved, reprecipitated and
dried under vacuum (10~2 bar, 60°C) for 14 hours. The poly(VDF-fer-TrFE-terWO
2014/162080 11 PCT/FR2014/050721
1234yf) terpolymer, in the form of a white powder, is characterized by
1H NMR spectroscopy (figure 3a) and 19F NMR spectroscopy (figure 3b).
The yield by weight is 58%.
5 Example 4 - Synthesis of polv(VDF-fe/--TrFE-fer-1234yf) (VDF: 60%; TrFE:
35%; 1234yf: 5% - initial molar ratios)
The synthesis of the poly(VDF-fer-TrFE-ter-1234yf) polymer is carried
out according to the same protocol as in example 1.
In detail, the operation is carried out as above in a 100 ml HC-276
10 reactor by respectively introducing therein the TBPPI (0.604 g, i.e.
3.47 mmol) and 60 ml of 1,1,1,3,3-pentafluorobutane. After cooling the
reactor, the 1234yf (1.49 g, i.e. 0.013 mol), the TrFE (7.47 g, i.e. 0.091 mol)
and then the VDF (10 g, i.e. 0.156 mol) are successively introduced therein.
As above, the reactor is heated to 74°C, showing an increase in the
15 pressure inside the reactor and then a decrease in the pressure, related to
the conversion of the gaseous fluorinated monomers to give the desired
terpolymer. At 74°C, the pressure is close to 22 bar (exothermicity up to
76°C). During the hour following this exotherm, the pressure falls to 8 bar for
a temperature maintained at 74°C.
20 As above, after reaction and cooling, the reactor is left in ice for 30 min
and then vented. After opening, the solvent is distilled off. The product is
precipitated from cold pentane, filtered off and dried under vacuum (10~2 bar,
60°C) for 14 hours. The poly(VDF-fer-TrFE-ter-1234yf) terpolymer, in the
form of a white powder, is characterized by 1H NMR spectroscopy (figure 4a)
25 and 19F NMR spectroscopy (figure 4b). The yield by weight is 72%.
Example 5 - Synthesis of polv(VDF-fer-TrFE-fer-1234vf) (VDF: 58%: TrFE:
39%: 1234vf: 3% - initial molar ratios)
The synthesis of the poly(VDF-fer-TrFE-fer-1234yf) polymer is carried
30 out according to the same protocol as in example 1.
In detail, the operation is carried out as above in a 100 ml HC-276
reactor by respectively introducing therein the TBPPI (0.659 g, i.e. 3.78 mol)
and 60 ml of 1,1,1,3,3-pentafluorobutane. The reactor is subsequently cooled
and then the 1234yf (2 g, i.e. 0.017 mol) and the TrFE (16 g, i.e. 0.195 mol),
35 followed by the VDF (10 g, i.e. 0.296 mol), are introduced therein.
The reactor is gradually heated to 74°C and, during the
polymerization, an increase in the pressure, which is close to 33 bar, is
WO 2014/162080 12 PCT/FR2014/050721
10
followed by a fall to 10 bar for a temperature maintained at 74°C. As above,
after cooling, the reactor is cooled and then vented. After opening and
distillation of the solvent, the terpolymer is precipitated from cold pentane,
filtered off and dried under vacuum (10"2 bar, 60°C).
The poly(VDF-fer-TrFE-fer-1234yf) terpolymer, in the form of a white
powder, is characterized by 1H NMR spectroscopy (figure 5a) and 19F NMR
spectroscopy (figure 5b). The yield is 69%.
Example 6 - Synthesis of polvM3F-fer-TrFE-fer-2-chloro-3,3,3-trifluoropropene)
terpolymer (VDF: 60%; TrFE: 35%; comonomer: 5% - initial molar
ratios)
The synthesis of the poly(VDF-fer-TrFE-ter-2-chloro-3,3,3-
trifluoropropene) polymer is carried out according to the following scheme:
15
P F
VDF
60%
H F
TrFE
35%
a
H2C=C
CF3
CoM
5%
TSPPf
C4F&Hb, 75:C
01 F ^
[CHrCF2^CH2-C-^C-CF4JCF,
H j
This polymerization is carried out as above in a 100 mi reactor by
respectively introducing therein the TBPPI (0.604 g, i.e. 3.47 mol) and 60 mi
of 1,1,1,3,3-pentafluorobutane. The reactor is subsequently cooled and then
20 the 2-chloro-3,3,3-trifluoropropene (1.71 g, i.e. 0.013 mol) and the TrFE
(7.47 g, i.e. 0.091 mol), followed by the VDF (10 g, i.e. 0.156 mol), are
successively introduced therein.
The reactor is heated to 74°C. During the polymerization, an increase
in pressure inside the reactor is observed (25 bar), followed by a decrease in
25 the pressure (12 bar) for a temperature maintained at 74°C.
As above, after cooling the reactor is cooled, then vented and opened.
The solvent is subsequently distilled off and then the terpolymer is
WO 2014/162080 13 PCT/FR2014/050721
precipitated from cold pentane, filtered off, redissolved, reprecipitated and
dried under vacuum (10"2 bar, 60°C) for 14 hours. The poly(VDF-fer-TrFE-fercoM)
terpolymer, in the form of a white powder, is characterized by 1H NMR
spectroscopy (figure 6a) and 19F NMR spectroscopy (figure 6b). The yield
by weight is 87%.
10
Example 7 - Synthesis of polv(VDF-fer-TrFE-fe/--dimethyl vinylphosphonate)
terpolymer (VDF; 60%; TrFE: 35%; comonomer: 5% - initial molar ratios)
The synthesis of the poly(VDF-fer-TrFE-ter-dimethyl
vinylphosphonate) polymer is carried out according to the following scheme;
F
nCH2=CF2 +
VDF
60%
K +
H F
=/ + H2C=CH
TrFE
35%
CoM
5%
OMe
TBPPI
C4FSH5, 75°C
H
(CH2-CF2MCH2-C-W-Cri-CF^ -
Froue
OMe
As in the preceding examples, a 100 ml HC-276 reactor is vented and
placed under vacuum and TBPPI (0.604 g, i.e. 3.47 mol), dimethyl
vinylphosphonate (1.76 g, i.e. 0.013 mol) and 60 ml of 1,1,1,3,3-
15 pentafluorobutane are respectively introduced therein. The reactor is
subsequently cooled and then the TrFE (7.47 g, i.e. 0.091 mol), followed by
the VDF (10 g, i.e. 0.156 mol), are subsequently transferred therein.
The reactor is gradually heated to 74°C. During the polymerization, an
increase in the pressure inside the reactor is observed (22 bar), followed by a
20 decrease in the pressure (17 bar).
After reaction, the reactor is cooled, vented and then opened and the
solvent is subsequently distilled off. The product is precipitated from cold
pentane, filtered off and dried under vacuum (10~2bar, 60°C) for 14 hours.
The poiy(VDF-fer-TrFE-fer-coM) terpolymer, in the form of a clear elastomer,
WO 2014/162080 14 PCT/FR2014/050721
is characterized by 1H NMR spectroscopy (figure 7a) and 19F NMR
spectroscopy (figure 7b). The yield by weight is 26%.
Example 8 - Synthesis of polv(VDF-fer-TrFE-rer-itaconic acid) terpolymer
(VDF: 60%; TrFE: 35%; comonomer: 5% - initial molar ratios)
The synthesis of the poly(VDF-ter-TrFE-fer-itaconic acid) polymer is
carried out according to the following scheme:
nCH2=CF2 +
VDF
60%
F. F
> = < •
H F
TrFE
35%
H2C=C
CoM
5%
C02H
TBPPI
C4F5H5, 75°C
C02H F
(CH2-CF2^CH2-c4fcH-CF2^:
C02H
-C02H
The TBPPI (0.604 g, i.e. 3.47 mol), the itaconic acid (1.69 g, i.e.
10 0.013 mol), 50 ml of 1,1,1,3,3-pentafluorobutane and 10 ml of distilled water
are respectively introduced into a 100 ml HC-276 reactor. The reactor is
subsequently cooled and then the TrFE (7.47 g, i.e. 0.091 mol) followed by
the VDF (10 g, i.e. 0.156 mol), are transferred therein.
The reactor is gradually heated to 74°C and an increase in the
15 pressure to 25 bar, followed by a fall to 13 bar, is recorded.
After reaction and cooling, the reactor is vented and then opened. The
solvent is distilled off. The product is precipitated from cold pentane, filtered
off and dried under vacuum (10"2 bar, 60°C) for 14 hours. The poiy(VDF-fer-
TrFE-ter-coM) polymer, in the form of an off-white elastomer, is characterized
20 by 1H NMR spectroscopy (figure 8a) and 19F NMR spectroscopy (figure 8b).
The calculated yield is 44%.
WO 2014/162080 15 PCT/FR2014/050721
Example 9 - Synthesis of poly(VDF-fer-TrFE-fer-a,g-difluoroacrvlic acid)
terpolymer (VDF: 60%; TrFE: 35%; comonomer: 5% - initial molar ratios)
The synthesis of the poly(VDF-ter-TrFE-ter-ct,|3-difluoroacrylic acid)
polymer is carried out according to the following scheme:
nCH2=CF2 +
VDF
60%
) = < •
H F
TrFE
35%
H C02H
J CoM
5%
TBPPI
C4F5H5, 75 °C
[ H f°2" F ]
~ f H2-CF2^-C~C~^fc^-CF2- p
F F K
5 As above, a 100 ml HC-276 reactor is placed under vacuum and then
the TBPPI (0.604 g, i.e. 3.47 mol), the a.p-difluoroacrylic acid (1.40g, i.e.
0.013 mol) and 60 ml of 1,1,1,3,3-pentafluorobutane are respectively
introduced. The reactor is subsequently cooled and then the TrFE (7.47 g,
i.e. 0.091 mol), followed by the VDF (10 g, i.e. 0.156 mol), are successively
10 introduced therein.
The reactor is gradually heated to 74°C and an increase in the
pressure is noted (26 bar), followed by a fall to 8 bar.
After reaction and cooling, the reactor is vented and then opened. The
solvent is subsequently distilled off. The product is precipitated from cold
15 pentane, filtered off and dried under vacuum (10~2 bar, 60°C) for 14 hours.
The poly(VDF-ter-TrFE-fer-a,p-dif!uoroacry!ic acid) terpolymer, in the form of
an off-white elastomer, is characterized by 1H NMR spectroscopy (figure 9a)
and 19F NMR spectroscopy (figure 9b). The yield by weight is 79%.
The conditions and the results of the preceding syntheses are
20 summarized in the following table:
WO 2014/162080 16 PCT/FR2014/050721
VDF
init. (%)
TrFE
init. (%)
CoM
init. (%)
VDF
fin. (%)
TrFE
fin. (%)
CoM
fin. (%)
TBPPI
(%)
*max
(bar)
AP (bar)
Yield
(%)
(g/mol)
PDI
Tdio%
Tg (°C)
Tm (°C)
TC(°C)
Ex.1
80
15
5
81
10
9
1
34
22
62
20 000
1.62
403
-40
111
86
Ex.2
70
25
5
76
16
8
1
37
24
88
30 300
1.49
406
-25
106
93
Ex.3
57
33
10
61
23
16
1
25
16
58
22 400
1.65
391
-15
41/109
28/94
Ex.4
60
. 35
5
66
27
7
1
20
1 5 ,
72
22 200
1.52
380
-39
36/105
24/87
Ex.5
58
39
3
65
30
5
0.5
33
23
69
31600
1.48
389
-19
28/116
25/97
Ex.6
60
35
5
65
33
2
1
25
13
87
26 000
1.69
390
-22.
54/127
39/110
Ex.7
60
35
5
50
32
18
1
25
3
26
15 000
1.72
nd
nd
nd
nd
Ex.8
60
35
5
65
25
10
1
22
5
44
nd
nd
nd
nd
nd
nd
Ex.9
60
35
5
65
30
5
1
25
13
79
nd
nd
nd
nd
nd
nd
In this table, the three lines VDF init., TrFE init. and CoM init. give the
molar composition of each of the monomers in the reaction mixture; the three
lines VDF fin., TrFE fin. and CoM fin. give the molar composition of each of
the units in the terpolymer synthesized; the line TBPPI gives the molar
proportion of initiator used; the line Pmax gives the maximum pressure
reached in the reactor during the polymerization; the line AP gives the fall in
pressure observed after the exotherm during the reaction; the line Yield gives
the yield by weight obtained; the line Mn gives the number-average molar
mass of the terpolymer, as determined by size exclusion chromatography
with a polymethyl methacrylate standard; the line PDI gives the polydispersity
index, as determined by the same method; the line Tdi0% gives the
decomposition temperature (10% weight loss) of the terpolymer, as
determined by thermogravimetric analysis under air, at 10°C/min; the line Tg
gives the glass transition temperature of the terpolymer, as determined by
differential scanning caiorimetry (DSC); the line Tm gives the melting
temperature of the terpolymer, as determined by differential scanning
caiorimetry (DSC); and the line Tc gives the crystallization temperature of the
terpolymer, as determined by differential scanning caiorimetry (DSC).

CLAIMS
1. A random linear copolymer obtained by copolymerization of
vinylidene fluoride, of trifluoroethylene and of at least one third
monomer, the third monomer having a molar mass of greater
than 100 g/mol and corresponding to the formula:
in which Rt represents a hydrogen atom or a fluorine atom and
R2 and R3 are chosen, independently of one another, from CI,
F, CF3, phosphonate, carboxylic acid, SO2X, where X
represents F, OK, ONa or OH, or Si(OR)3, R representing a
methyl, ethyl or isopropyl group.
2. The copolymer as claimed in claim 1, in which the third
monomer is chosen from 2,3,3,3-tetrafluoropropene, 2-chloro-
3,3,3-trifluoropropene, a,p-difluoroacrylic acid, 2-
(trifluoro)methacrylic acid, dimethyl vinylphosphonate,
bromotrifluoroethylene, vinyl trifluoroacetate, itaconic acid and tbutyl
2-(trifluoromethyl)acrylate.
3. The copolymer as claimed in claim 1 or 2, in which:
- the molar proportion of units resulting from the vinylidene
fluoride monomer is from 40 to 90% and preferably from 55
to 80%;
- the molar proportion of units resulting from the
trifluoroethylene monomer is from 5 to 50% and preferably
from 10 to 40%; and
- the molar proportion of units resulting from the third
monomer is from 1 to 20% and preferably from 2 to 18%.
4. A process for the preparation of a copolymer comprising a
stage of copolymerization of a reaction mixture of vinylidene
fluoride, of trifluoroethylene and of at least one third monomer
having a molar mass of greater than 100 g/mol, the third
monomer corresponding to the formula:
in which Ri represents a hydrogen atom or a fluorine atom and
R2 and R3 are chosen, independently of one another, from CI,
F, CF3 and functional groups selected from phosphonate,
carboxylic acid, SO2X (where X represents F, OK, ONa or OH)
or Si(OR)3 (R representing a methyl, ethyl or isopropyl group)
groups.
5. The process as claimed in claim 4, in which the third monomer
is chosen from 2,3,3,3-tetrafluoropropene, 2-chloro-3,3,3-
trifluoropropene, a,p-difluoroacrylic acid, 2-(trifluoro)methacryiic
acid, dimethyl vinylphosphonate, bromotrifluoroethylene, vinyl
trifluoroacetate, itaconic acid and t-butyl 2-
(trifluoromethyl)acrylate.
6. The process as claimed in claim 4 or 5, in which:
- the molar proportion of vinylidene fluoride in the reaction
mixture is from 40 to 90% and preferably from 55 to 80%;
- the molar proportion of trifluoroethylene in the reaction
mixture is from 5 to 50% and preferably from 10 to 40%;
and
- the molar proportion of the third monomer in the reaction
mixture is from 1 to 20% and preferably from 2 to 18%;
the molar proportions being with respect to the sum of the
vinylidene fluoride, trifluoroethylene and third monomer.
7. The process as claimed in one of claims 4 to 6, in which the
reaction mixture is devoid of chain-transfer agent.
8. The process as claimed in one of claims 4 to 7, in which the
reaction mixture is essentially composed of and preferably
consists of a mixture of vinylidene fluoride, of trifluoroethylene,
of at least one third monomer, of radical initiator and of solvent
and/or of water.
9. the process as claimed in one of claims 4 to 8, in which the
reaction mixture is heated up to a temperature for initiation of
reaction of between 60 and 90°C, preferably between 70 and
^0°C and more particularly between 72 and 76°C.
10. The copolymer as claimed in one of claims 1 to 3 prepared by
the process of one of claims 4 to 9.
11. A film or membrane comprising at least one copolymer as
claimed in one of claims 1 to 3 or 10.
12. A piezoelectric device comprising a film as claimed in claim 11.
13. A ferroelectric device comprising a film as claimed in claim 11.
14. A pyroelectric device comprising a film as claimed in claim 11.
15. A coating comprising a film as claimed in claim 11.