Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/08—Materials not undergoing a change of physical state when used
  • C09K5/14—Solid materials, e.g. powdery or granular
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F214/18—Monomers containing fluorine
  • C08F214/182—Monomers containing fluorine not covered by the groups C08F214/20 - C08F214/28
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F214/18—Monomers containing fluorine
  • C08F214/22—Vinylidene fluoride
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F214/18—Monomers containing fluorine
  • C08F214/24—Trifluorochloroethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/26—Removing halogen atoms or halogen-containing groups from the molecule
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
  • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C09D127/16—Homopolymers or copolymers of vinylidene fluoride
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/80—Constructional details
  • H10N30/85—Piezoelectric or electrostrictive active materials
  • H10N30/857—Macromolecular compositions
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08J2327/16—Homopolymers or copolymers of vinylidene fluoride
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]

Definitions

• Electrocaloric polymer ink and film including and associated uses
• the invention relates to the field of electrocaloric materials.
• the invention relates to an electroactive polymer exhibiting a significant electrocaloric effect, that is to say a significant adiabatic temperature variation, when the polymer is subjected to a variable electric field.
• the invention also relates to an ink and a film based on the electroactive polymer.
• the invention ultimately relates to various possible uses of the polymer, in particular in the form of a film.
• the electrocaloric effect is a property of certain dipolar dielectric materials which manifests itself by a variation in temperature when subjected to a variable electric field.
• the physical origin of this phenomenon is linked to the change in the dipolar order, and therefore to a variation in dipolar entropy induced by the application of an electric field.
• the application of an electric field E c orders and orients the dipoles of these materials, which causes a decrease in their dipolar entropy and an increase in their temperature under adiabatic conditions.
• the reduction or elimination of the electric field causes an increase in their dipolar entropy and a decrease in their temperature under adiabatic conditions.
• an electrocaloric material is characterized, under given experimental conditions, by an adiabatic temperature variation ATEC for an applied electric field Ec under adiabatic conditions.
• an electrocaloric material can also be characterized by an isothermal entropy change ASEC for an applied electric field Ec under isothermal conditions.
• the electrocaloric effect is currently the subject of numerous studies for the development of new cooling systems, more environmentally friendly and more energy efficient than systems operating on the basis of gas compression, the thermoelectric effect or again the magnetocaloric effect [see: SHI, Junye, HAN, Donglin, Ll, Zichao, et al. Electrocaloric cooling materials and devices for zero-global- warming-potential, high-efficiency refrigeration. Joule, 2019]. Ferroelectric materials and ferroelectric relaxers, due to a strong coupling between the applied electric fields and their dipolar structure, are the materials that arouse the most interest for these applications because they are likely to have significant electrocaloric performance.
• this coupling is maximum near or slightly above the phase transitions: Ferroelectric -> Paraelectric (FE -> PE) or Ferroelectric Relaxer -> Paraelectric (RFE -> PE), due in particular to a strong reversible variation of the polarization of these materials under an electric field, as well as a high dielectric permittivity.
• FE -> PE Ferroelectric -> Paraelectric
• RFE -> PE Ferroelectric Relaxer -> Paraelectric
• a relatively small variation in the electric field generates large variations in entropy and temperature.
• the good flexibility and the ease of processing of these materials in the form of thin films of large surface are other parameters which make them particularly suitable for use in solid refrigeration systems.
• fluoropolymers based on VDF and TrFE have been the most studied. They present the best performances to date.
• VDF-TrFE P-type ferroelectric copolymers
• FE -> PE Ferroelectric -> Paraelectric
• the FE -> PE transition of this type of polymer is narrow, i.e. it takes place over a low temperature range, and is located at relatively high temperatures, typically strictly above 60 ° C. This prevents their use in the sense of cooling systems having to operate around room temperature and / or over a wide range of temperatures.
• ferroelectric relaxer polymers overcomes at least some of the disadvantages mentioned above. Indeed, ferroelectric relaxer polymers of the type: irradiated P (VDF-TrFE), P (VDF-TrFE-CFE), or P (VDF-TrFE-CTFE), have a phase transition (RFE -> PE) widened by compared to the phase transition FE -> PE of ferroelectric polymers, that is to say which takes place over a wider temperature range. In addition, the RFE -> PE transition occurs at temperatures generally lower than those of the FE -> PE transition of ferroelectric polymers. Thus, this makes it possible to envisage a use of the ferroelectric relaxer polymers in various cooling systems, in particular in cooling systems having to operate around room temperature and / or over a wide range of temperatures.
• the electrocaloric performance of a material can be estimated theoretically (indirect method) from its dielectric properties, using an equation obtained from Maxwell's relations: in which :
• ATEC designates the adiabatic temperature variation of the material
• T denotes the temperature of the material
• CE designates the heat capacity of the material
• P denotes the dielectric polarization of the material
• E denotes the electric field varying between a minimum value Ei and a maximum value E2.
• Neese et al. have for example been able to estimate by a so-called "indirect” method that ferroelectric copolymers of type P (VDF-TrFE) composed of 55 mol% of VDF and 45% of TrFE, having a Curie temperature (Transition FE-> PE) of about 70 ° C, can generate adiabatic temperature variations (ATEC) of 12 ° C to about 80 ° C for a strong electric field of 209 V / pm.
• VDF-TrFE ferroelectric copolymers of type P
• TrFE having a Curie temperature (Transition FE-> PE) of about 70 ° C
• TAC adiabatic temperature variations
• Li et al. have for example been able to measure, directly, that P relaxer terpolymers (VDF-TrFE-CFE) of composition 59.2 / 33.6 / 7.2 mol% could show, significant electrocaloric effects in a wider range of temperatures, around 40 ° C.
• An adiabatic ATEC temperature variation up to 7.6 ° C could thus be measured at 30 ° C under an electric field of 100 V / pm [see: LI, Xinyu, QIAN, Xiao-shi, LU, S. G., et al.
• VDF-based fluoropolymers having improved electrocaloric properties, i.e. having a higher ATEC adiabatic temperature variation, in a field. variable electric given.
• the electric field used to obtain the high adiabatic temperature variation must be as low as possible to limit the energy consumption and limit the use of expensive and dangerous control electronics.
• WO 2019075061 postulates, without giving an example, that polymers of formula (I):
• n and m are integers independently selected between 1 and 1000 and p is an integer greater than n + m; R-i, F, R3, R4 being chosen independently from: -H, -F, -Cl, -Br,
• Z being, at each occurrence of a unit, independently chosen from a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, would have interesting electrocaloric properties.
• a process for preparing polymers (I) has been disclosed and consists of bringing an initial polymer (II) into contact with an alkali hydroxide (strong base pKa> 14), such as LiOH, NaOH, KOH or CsOH, in order to cause dehydrohalogenation , the polymer (II) having the formula:
• WO 2019075061 shows the manufacture of a polymer comprising double bonds, this polymer being made from the dehydrofluorination of PVDF in dimethylacetamide with a saturated solution of sodium hydroxide in isopropanol.
• fluoropolymers comprising conjugated double bonds obtained by dehydrofluorination thanks to the action of a strong base leads to polymers which are not thermally stable, which turn yellow, easily degrade and are likely to crosslink during the action of a strong base.
• the process has an operational disadvantage in that it uses dimethylacetamide as solvent, which is harmful (by contact / inhalation) and CMR (may harm the fetus).
• dimethylacetamide as solvent
• CMR may harm the fetus.
• VDF-based fluoropolymers having improved electrocaloric properties, i.e. having a higher ATEC adiabatic temperature variation, in a given variable electric field and in a given environment (temperature conditions).
• the electric field used to obtain a high adiabatic temperature variation should preferably be as low as possible, in order to limit energy consumption and to limit the use of expensive and dangerous control electronics (high voltages).
• the present invention proposes to provide a fluoropolymer improved over those of the prior art, exhibiting a significant electrocaloric effect when subjected to a varying electric field, as well as a composition and a film derived therefrom, and uses. associated.
• the aim is also to provide, according to at least some embodiments, an improved fluoropolymer having high dielectric strength in order to withstand many cycles of electric fields without breakdown.
• the objective is further to provide, in at least some embodiments, an improved fluoropolymer exhibiting good thermal and / or chemical stability in order to envision the durable and reliable use of the polymer in devices.
• the invention relates to a polymer exhibiting an electrocaloric effect under the effect of a variable electric field, said polymer comprising:
• Xi and X2 independently denote: -H, -F, or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
• X3 and X4 independently denote: -F, or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated, except the combination in which: X1 and X2 are both: -Fl and X3 and X4 are both: -F,
• Yi and Y2 independently denote: -Fl, -F, -Cl or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
• Y3 denotes: -F, -Cl or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
• Z denotes a halogen atom other than: -F, and N is a number ranging from 0.1 to 10.0.
• the polymer according to the invention essentially does not have a conjugated carbon-carbon double bond.
• the inventors of the present invention have found, completely surprisingly, that such polymers have better electrocaloric properties than polymers of substantially identical compositions but without double bonds and / or than polymers of substantially identical compositions but with conjugated double bonds. , under the same conditions of electric field variation and at the same measurement temperature. Their observation is based on measurements of adiabatic temperature variations implemented on a test bench 1 as shown in FIG. 1, on polymers according to the invention. They compared these measurements to measurements made on polymers of substantially identical composition but without carbon-carbon double bonds and / or polymers of substantially identical composition but with conjugated carbon-carbon double bonds, under the same conditions of field variation. electric and at the same measurement temperature. The inventors have also observed that at least some of these polymers, or even most of these polymers, are chemically and thermally stable and have good dielectric strength.
• Xi can denote: -H or -F; and, X2, X3 and X4 all three denote: -F.
• Z denotes: -Cl.
• Y3 denotes: -F and, Y1 and Y2 both denote: -H or -F.
• the polymer according to the invention comprises at least 1 mol%, preferably at least 2 mol%, more preferably at least 3 mol% of unit of formula, and extremely preferably at least 4% molar unit of formula (V).
• the polymer with X1 denoting: -Fl; X2, X3 and X4 denoting all three: -F; Y3 denoting: —F; Y1 and Y2 both denoting: -Fl; and, Z denoting -Cl; has a value of N chosen between 0.1 and 2, preferably between 0.1 and 1.5 and more preferably still between 0.1 and 1.
• the polymer with X1 denoting: -Fl; X2, X3 and X4 denoting all three: -F; Y-i, Y2 and Y3 denoting all three: -F; and Z denoting: -Cl; has a value of N chosen between 0.1 and 10.0, preferably between 1.0 and 8.0, more preferably between 2.0 and 7.5 and extremely preferably between 2.2 and 7.0.
• the polymer according to the invention is advantageously a ferroelectric-relaxer polymer.
• the polymer has a remanent polarization of less than or equal to 20 mC / m 2 and / or a coercive field of less than or equal to 25 n.mht 1 , with both the remanent polarization and coercive field measurements being taken. operating at a temperature of 25 ° C, at a frequency of 1 FHz, and at a field of 150 V / pm.
• the polymer has a weight average molecular mass greater than or equal to 200,000 g / mol, preferably greater than or equal to 300,000 g / mol, preferably greater than or equal to 400,000 g / mol.
• the polymer has an enthalpy of fusion greater than or equal to 10 J / g, preferably an enthalpy of fusion greater than or equal to 15 J / g, the enthalpy of fusion being measured according to the ISO 11357-2 standard. : 2013, in second heating with temperature ramps of 10 ° C / min.
• a high weight average molecular mass makes it possible in particular to achieve high crystallization rates of the polymer.
• Polymers having a high weight average molecular mass and / or a high degree of crystallization have in particular better dielectric strength and particularly advantageous mechanical properties allowing the manufacture of sufficiently mechanically resistant films.
• the polymer has a relative dielectric permittivity greater than or equal to 15, preferably greater than or equal to 20, still more preferably greater than or equal to 40, and extremely preferably greater than or equal to 55, over a temperature range of at least 5 ° C, preferably at least 10 ° C, preferably at least 20 ° C and extremely preferably at least 30 ° C, said relative dielectric permittivity being measured at 1 kHz.
• the polymer has a maximum permittivity at a temperature less than or equal to 60 ° C, preferably at a temperature less than or equal to 50 ° C and more preferably at a temperature less than or equal to 40 ° C, said elative dielectric permittivity being measured at 1 kHz.
• the polymer according to the invention is capable of being obtained by a process comprising: a) providing an initial polymer comprising, in total moles of polymer:
• the polymer obtained has an adiabatic temperature variation which is at least greater than 0.5 ° C, preferably at least greater than 1 ° C, more preferably at least greater than 1.5 ° C, for example. relative to the adiabatic temperature variation of the initial polymer at at least one measurement temperature, the measurements of adiabatic temperature variations being carried out at a variable electric field of amplitude equal to 86 V / pm.
• the polymer has a maximum of relative dielectric permittivity which is at least greater than 5%, preferably at least greater than 10% and more preferably at least greater than 25%, relative to the maximum dielectric permittivity of said polymer. initial, said relative dielectric permittivity being measured at 1 kHz.
• the dehydrohalogenation step in the process is carried out with a reaction progress of at least 0.1, preferably with a reaction progress of at least 0.2.
• the invention also relates to a composition
• a composition comprising one or more polymers according to the invention and one or more liquid vehicle (s).
• the invention also relates to a film comprising the polymer according to the invention.
• the film has a thickness greater than or equal to 0.1 micrometers. Preferably, it can have a thickness ranging from 1 micrometer to 100 micrometers. More preferably, it may have a thickness ranging from 1 micrometer to 50 micrometers, in particular a thickness ranging from 1 micrometer to 10 micrometers. If the thickness of the film is too thin, it becomes too mechanically fragile. If the film thickness is too great, too high voltages must be applied to obtain a given electric field.
• the invention relates to possible uses of the polymer, in particular of the polymer in the form of a film.
• the polymer according to the invention can be used in a heat transfer system, in particular a cooling system.
• the polymer according to the invention can also be used in an energy storage system, in particular a capacitor, in an organic transistor, in an actuator, or else in an electrostatic clutch.
• Fluorinated polymer comprising substantially non-conjugated double bonds
• the polymer according to the invention comprises, preferably consists essentially of, more preferably consists of:
• Xi and X2 independently denote: -Fl, -F, or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
• X3 and X4 independently denote: -F, or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated, except the combination where: X1 and X2 are both: -Fl and X3 and X4 are all two: -F,
• Yi and Y2 independently denote: -Fl, -F, -Cl or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
• Y3 independently denote: -F, -Cl or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
• Z denotes a halogen atom other than: -F, and N is a number from 0.1 to 10.
• the molar composition of the units in fluoropolymers can be determined by various means such as infrared spectroscopy or RAMAN spectroscopy.
• Multi-core NMR techniques can also be used, in particular proton ( 1 H) and fluorine ( 19 F), by analysis of a solution of the polymer in an appropriate deuterated solvent.
• the NMR spectrum is recorded on an NMR-FT spectrometer equipped with a multi-nuclear probe.
• the specific signals given by the different monomers are then identified in the spectra produced according to one or the other nucleus.
• the unit resulting from the polymerization of VDF gives in proton NMR a specific signal for the -CH2- groups (bulk centered at 3 ppm).
• the unit obtained from TrFE gives in proton NMR a specific signal characteristic of the -CHF- group (at approximately 5 ppm).
• fluorine NMR the signals originating from the -CF2- and -CFCI- units, from CFE and CTFE, are merged with those from the -CF2- units of VDF and TrFE between -90 and -132 ppm.
• the -CHF- unit of TrFE gives characteristic signals between -194 and -220 ppm.
• the presence of conjugated and unconjugated double bonds in fluoropolymers can be evaluated by various spectroscopy methods and in particular RAMAN spectroscopy.
• Conjugated double bonds are observed by wider valence vibration bands and at lower wavenumbers, between 1500 and 1700 cm 1 .
• the presence of double bonds can be quantified by proton NMR by the appearance of signals between 6.0 and 6.7 ppm.
• the inventors were able to demonstrate that the presence of 0.1% to N% of units having carbon-carbon double bonds, these double bonds being non-conjugated in the structure of the polymer, made it possible to obtain polymers having a high relative dielectric constant and / or a strong electrocaloric effect.
• these polymers are, at least according to certain embodiments, stable over time under usual conditions of use and implementation. That is to say that under the usual conditions of use, in particular the uses provided for in the present application, they do not degrade or only slightly, they do not yellow or slightly, they do not crosslink or only slightly, their viscosity in solution or melt does not vary or slightly.
• the polymer comprises from 30% to 90 mol%, based on the total number of moles of units of the composition of the polymer, of units derived from vinylidene difluoride.
• the polymer can comprise from 30% to 35% molar, from 35% to 40% molar, from 40% to 45% molar, from 45% to 50% molar, from 50% to 60% molar, from 60% to 70% molar, from 70% to 80% molar, from 80% to 85% molar or from 85% to 90% molar of units obtained from vinylidene.
• the polymer comprises from 1% to 59.9 mol%, based on the total number of moles of units of the composition of the polymer, of unit (s) of formula (IV).
• the polymer can comprise from 5% to 10% molar, from 10% to 15% molar, from 15% to 20% molar, from 20% to 30% molar, from 40 to 50% molar, of 50 to 55 mol%, or from 55% to 59.9 mol% of unit (s) of formula (IV).
• the polymer may comprise a single unit of formula (IV) or, on the contrary, several different units of formula (IV).
• the unit (s) of formula (IV) may / may be derived from monomeric unit (s) chosen from the list consisting of: trifluoroethylene (TrFE), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), trifluoropropenes, and in particular 3,3,3-trifluoropropene, tetrafluoropropenes and in particular 2, 3,3,3-tetrafluoropropene or 1, 3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes and in particular 1, 1, 3,3,3-pentafluoropropene or 1, 2,3,3,3-pentafluoropropene.
• TrFE trifluoroethylene
• TFE tetrafluoroethylene
• HFP hexafluoropropylene
• trifluoropropenes and in particular 3,3,3
• units of formula (IV) derived from several different fluorinated monomers may be present in the polymer.
• Xi can denote: -H or -F; and, X2, X3 and X4 denote all three: -F.
• the polymer according to the invention can therefore be a copolymer comprising units derived from trifluoroethylene (TrFE) and / or tetrafluoroethylene (TFE).
• Z can denote: -Cl, -Br or -I.
• Z can denote: -Cl.
• the polymer comprises 0% to (20-N) mol%, relative to the total number of moles of units of the composition of the polymer, of units of formula (V), N being a number ranging from 0.1 to 10 , 0.
• the polymer can comprise at least 1 mol%, preferably at least 2 mol%, more preferably at least 3 mol% and extremely preferably at least 4 mol% of unit (s) of formula (V).
• unit (s) of formula (V) in addition to the units of formulas (III) and (IV) generally makes it possible to obtain a polymer of ferroelectric relaxer type, the advantages of which are detailed below.
• the polymer can comprise from 4% to 15 mol% of unit (s) of formula (V).
• the polymer may comprise a single unit of formula (V) or, on the contrary, several different units of formula (V).
• the unit (s) of formula (V) may / may be derived from monomeric unit (s) chosen from the list consisting of: 1, 1-chlorofluoroethylene ( 1, 1 -CFE), 1, 2-chlorofluoroethylene (1, 2-CFE), chlorotrifluoroethylene (CTFE), 2-chloro-3,3,3-trifluoropropene (1233xf), 1-chloro-3,3 , 3-trifluoropropene (1233zd), 1, 2-dichloro-1, 2-difluoroethylene, 1, 1 -dichloro-1, 1 - difluoroethylene and 1, 1, 2-trichloro-2-fluoroethylene.
• monomeric unit (s) chosen from the list consisting of: 1, 1-chlorofluoroethylene ( 1, 1 -CFE), 1, 2-chlorofluoroethylene (1, 2-CFE), chlorotrifluoroethylene (CTFE), 2-chloro-3,3,3-trifluoropropene (1233xf), 1-chloro-3,3
• Y3 can denote: -F and, Y1 and Y2 both denote: -H or -F.
• the polymer can comprise units derived from 1,1 -CFE and / or CTFE.
• the polymer may comprise units derived from vinylidene fluoride (VDF), TrFE and CFE, or comprise units derived from VDF, TrFE and CTFE, or comprise units derived from VDF, TrFE, CFE and CTFE, or include units from VDF, TFE and CFE, or include units from VDF, TFE and CTFE, or include units from VDF, TFE, CFE and CTFE, said polymers all further comprising doubles essentially unconjugated carbon-carbon bonds.
• the polymers of the above list can also comprise units resulting from one or more additional monomers, such as, for example, units resulting from HFP.
• N is a number between 0.1 and 10 corresponding to the molar percentage of said ethylenic units relative to the total number of moles of units of the composition of the polymer.
• N can in particular be a number ranging from 0.1 to 0.2 or ranging from 0.2 to 0.3, or ranging from 0.3 to 0.5, or ranging from 0.5 to 1.0, or ranging from 1.0 to 2.0, or ranging from 2.0 to 3.0, or ranging from 3.0 to 4.0, or ranging from 4.0 to 5.0, or ranging from 5.0 to 6.0, or ranging from 6.0 to 7.0, or ranging from 7.0 to 8.0, or ranging from 8.0 to 9.0, or even ranging from 9.0 to 10.0.
• the number "N" can advantageously be chosen so that at a temperature of intended use of the polymer, the dielectric and / or ATEC permittivity are maximum.
• N is preferably chosen between 0.1 and 2, more preferably between 0.1 and 1, 5 and extremely preferably between 0.1 and 1.
• the number N can in particular be chosen between 0.1 and 0.5.
• N is preferably chosen between 0.1 and 10.0, preferably between 1.0 and 8.0, preferably still between 2.0 and 7.5 and extremely preferably between 2.2 and 7.0.
• the number N can in particular be chosen between 3.0 and 6.5.
• the polymer has essentially no conjugated carbon-carbon double bond.
• conjugated carbon-carbon double bond is understood to mean any alternation of single bond (s) with double bonds, of the p-s-p type.
• the polymer has a proportion of conjugated carbon-carbon double bonds relative to the total number of carbon-carbon double bonds generally less than or equal to 10%, or less than or equal to 9%, or less than or equal to 8%, or less than or equal to 7%, or less than or equal to 6%, or less than or equal to 5%, or less than or equal to 4%, or less than or equal to 3%, or less than or equal to 2%.
• the polymer has a proportion of conjugated carbon-carbon double bonds relative to the total number of carbon-carbon double bonds less than or equal to 1%, or less than or equal to 0.1% and ideally tending towards 0.
• the polymer can be statistical and linear.
• the polymer according to the invention exhibits an electrocaloric effect under the effect of a variable electric field.
• the polymer exhibits an adiabatic temperature variation ATEC of at least 1 ° C. at at least one measurement temperature, the measurements of adiabatic temperature variations being carried out at an electric field of given amplitude DE.
• the measurement temperature corresponds to the temperature to which the sample is brought before it is subjected to the variation of the electric field DE causing the electrocaloric effect.
• the polymer exhibits an adiabatic ATEC temperature variation of at least 1.5 ° C, or at least 2 ° C, or at least 2.5 ° C, or at least 3 ° C, or at least 3.5 ° C, or at least 4.0 ° C, or at least 4.5 ° C, or at least 5 ° C, or at least 6 ° C, or at least 7 ° C, or at least 8 ° C, or at least 9 ° C, or at least 10 ° C, in a given variable field, at a given measurement temperature.
• the electric field used to demonstrate an electrocaloric effect must be variable. Indeed, it is the variation of the electric field which causes the electrocaloric effect. Generally, the greater the amplitude of the electric field, the greater the electrocaloric effect. However, the maximum amplitude of the electric field must be adapted so as not to reach the breakdown voltage of the polymer. In addition, the production of high voltages requires specific equipment which consumes a great deal of energy, which is not necessarily desirable.
• the electric field used to demonstrate a significant electrocaloric effect for a use as described later can have a maximum amplitude less than or equal to 500 V / pm, or less than or equal to 400 V / pm, or less than or equal to 300 V / pm, or less than or equal to 200 V / pm, or less than or equal to 150 V / pm, or less than or equal to 140 V / pm, or less than or equal to 130 V / pm, or less than or equal to 120 V / pm, or less than or equal to 110 V / pm, or less than or equal to 100 V / pm, or less than or equal to 90 V / pm.
• the electric field can have an amplitude greater than or equal to 30 V / pm, or greater than or equal to 40 V / pm, or greater than or equal to 50 V / pm MV. nr 1 .
• the polymer has a dielectric strength greater than or equal to 200 V / pm, preferably greater than or equal to 300 V / pm, still more preferably greater than or equal to 400 V / pm and extremely preferably greater than or equal to 500 V / pm.
• Dielectric strength can be measured according to ASTM D3755-97.
• a square wave type electric field with a maximum value equal to DE and a minimum value equal to 0, can typically be used.
• the frequency of the electric field must be low enough to allow heat to diffuse through the polymer. Frequencies ranging from 1 mHz to 100 Hz, preferably frequencies ranging from 0.1 Hz to 10 Hz, may be used.
• the measurement temperature can be between the glass transition temperature and the melting temperature of the polymer.
• glass transition temperature is meant the temperature at which an amorphous polymer, at least partially, changes from a rubbery state to a glassy state, or vice versa, as measured by differential scanning calorimetry (DSC). according to ISO 11357-2: 2013, in second heating, in using a heating rate of 10 ° C / min.
• melting temperature is understood to denote the temperature at which a crystalline polymer, at least partially, passes into the viscous liquid state, as measured by differential scanning calorimetry (DSC) according to standard ISO 11357-3; 2018, in second heating, using a heating rate of 10 ° C / min.
• the measurement temperature can in particular be from -20 ° C to 150 ° C, preferably from 0 ° C to 100 ° C, more preferably from 15 ° C to 60 ° C and extremely preferably from 20 ° C to 40 ° C.
• the polymer can be a ferroelectric.
• "Conventional ferroelectric” polymers often referred to simply as “ferroelectric", of the P-type (VDF-TrFE), are characterized by a wide hysteresis cycle of the electric displacement-applied electric field curve. For these materials, this cycle is characterized by a high coercive field at 25 ° C, typically greater in absolute value than 45 V / pm and a high remanent polarization at 25 ° C, typically greater than 50 mC / m 2 . These materials have a maximum of their electrocaloric properties at temperatures close to their Curie temperature.
• the Curie temperature can be adjusted depending on the composition of the polymer: the higher the proportion of vinylidene fluoride, the higher the Curie temperature. This temperature typically varies between 60 ° C. and 150 ° C. for molar percentages of vinylidene fluoride in the copolymer P (VDF-TrFE) of between 55% and 82 mol%.
• Ferroelectric polymers have valuable electrocaloric properties, but these properties are limited to temperatures too high to be suitable for use in refrigeration devices suitable for many applications. Furthermore, the narrowness of the electrocaloric performance peak associated with the narrowness of the Curie transition limits their use.
• the polymer can be a ferroelectric relaxer.
• "Ferroelectric relaxer" polymers are characterized by a relaxer-ferroelectric (RFE) -> paraelectric (PE) crystal transition over a wide temperature range. At this transition, we observe a wide peak of dielectric permittivity, the temperature of this maximum depending on the frequency of the applied electric field: the lower the frequency of the electric field, the more the maximum dielectric permittivity is shifted towards low temperatures. .
• transition temperatures (RFE) -> (PE) or slightly higher the application of an electric field generates and aligns the nanopolar regions, inducing a variation in entropy, and thus a significant electrocaloric effect over a wide temperature range.
• the ferroelectric relaxers polymers are characterized at 25 ° C, and at a frequency of about 1 Hz by a hysteresis cycle of the curve "electrical displacement" as a function of the "applied electric field" much finer than the hysteresis cycle. of a ferroelectric polymer. They typically have a coercive field less than or equal in absolute value to 45 V / pm and a remanent polarization less than or equal to 40 mC / m 2 . According to certain preferred embodiments, the polymer according to the invention can have a coercive field less than or equal to 25 V / pm and a remanent polarization less than or equal to 20 mC / m 2 .
• Ferroelectric relaxer polymers are generally obtained by introducing defects into the crystal structure of ferroelectric polymers, thereby decreasing the size of the polar domains. This can for example be done by irradiating a conventional ferroelectric polymer. However, it is preferable to obtain a ferroelectric relaxer character by the presence of units derived from specific monomers, such CFE or CTFE.
• the phase transition corresponding to the maximum dielectric permittivity and / or the maximum of ATEC can be obtained at a lower temperature, in particular between 0 ° C and 100 ° C, and in some cases between 20 ° ( and 60 ° C.
• the ferroelectric relaxer polymers have interesting electrocaloric properties, over a wide temperature range, and in particular at temperatures close to ambient temperature They are therefore particularly advantageous for the production of electrocaloric devices.
• the polymer may have a weight average molecular mass greater than or equal to 200,000 g / mol, preferably greater than or equal to 300,000 g / mol, preferably greater than or equal to 400,000 g / mol.
• the molecular mass distribution can be estimated by SEC (size exclusion chromatography) with dimethylformamide (DMF) as eluent, with a set of 3 columns of increasing porosity.
• the stationary phase is a styrene-DVB gel.
• the detection method is based on a measurement of the refractive index, and the calibration is performed with polystyrene standards.
• the sample is dissolved at 0.5 g / L in DMF and filtered through a 0.45 ⁇ m nylon filter.
• the polymer has an enthalpy of fusion greater than or equal to 10 J / g, preferably an enthalpy of fusion greater than or equal to 15 J / g, the enthalpy of fusion being measured according to the ISO 11357-2 standard. : 2013, in second heating with temperature ramps of 10 ° C / min.
• the higher the enthalpy of fusion, or equivalent the higher the level of crystallinity the more intense the electrocaloric effect in the polymer will be.
• Dielectric permittivity is a physical property that describes the response of a given medium to a given electric field. It can be measured at 1 kHz at a given measurement temperature. A method of measuring the dielectric permittivity has been detailed in the part dedicated to the examples.
• the polymer according to the invention may have a relative dielectric permittivity greater than or equal to 15, preferably greater than or equal to 20, more preferably greater than or equal to 40, and extremely preferably greater than or equal to 55, over a temperature range of at least at least 5 ° C, preferably at least 10 ° C, preferably at least 20 ° C and extremely preferably at least 30 ° C.
• the maximum permittivity of the polymer is at a measurement temperature less than or equal to 60 ° C, preferably at a temperature less than or equal to 50 ° C and preferably still at a temperature less than or equal to 40 ° C.
• the polymer according to the invention can be obtained by the process comprising: a) providing an initial polymer comprising, preferably consisting essentially of, more preferably consisting of, in total moles of polymer:
• the polymer has an adiabatic temperature variation ATEC at least greater than 0.5 ° C, preferably at least greater than 1 ° C, even more preferably at least greater than 1.5 ° C, compared to the adiabatic temperature variation of the initial polymer at at least one measurement temperature, the measurements of adiabatic temperature variations being carried out at a variable electric field having a maximum amplitude equal to 86 V / pm.
• the initial polymer can be obtained according to methods known from the prior art. It can in particular be prepared by radical polymerization according to a polymerization process in solution, in suspension, in emulsion or in microemulsion. The copolymerization reaction is generally carried out in the presence of a radical initiator.
• This can be, for example, a t-alkyl peroxyester such as tert-butyl peroxypivalate (or TBPPI), tert-amyl peroxypivalate, a peroxydicarbonate such as bis (4-tert-butyl cyclohexyl) peroxydicarbonate, sodium, ammonium or potassium persulfate, benzoyl peroxide and its derivatives, a tert-alkyl hydroperoxide such as tert-butyl hydroxyperoxide, a t-alkyl peroxide such as tert-butyl peroxide or a t-alkyl -peroxyalkane such as 2,5-bis (tert-butylperoxy) -2,5-dimethylhexane.
• a t-alkyl peroxyester such as tert-butyl peroxypivalate (or TBPPI), tert-amyl peroxypivalate,
• an azo initiator or a redox system can be used as the radical initiator.
• the polymer can also be obtained by reduction of a copolymer of type P (VDF-CTFE) to give a copolymer of type P (VDF- T rFE-CTFE) (see: WANG, Zhiming, ZHANG, Zhicheng, and CHUNG, TC Mike. High dielectric VDF / TrFE / CTFE terpolymers prepared by hydrogenation of VDF / CTFE copolymers: synthesis and characterization. Macromolecules, 2006, vol. 39 , no 13, p. 4268-4271).
• the initial polymer can be selected according to its known electrocaloric properties.
• An initial polymer having good electrocaloric properties at temperatures close to the temperatures of use of the polymer according to the invention can be advantageously chosen.
• the initial polymer can be selected as a function of the temperature at which its dielectric constant is maximum.
• An initial polymer having a maximum dielectric constant at a temperature close to the temperatures of use of the polymer according to the invention will be advantageously chosen.
• Dehydrohalogenation of the initial polymer makes it possible to obtain carbon-carbon double bonds. Formally, it consists in the elimination of mainly one -Z atom and one hydrogen on carbon adjacent to that of the leaving -Z atom.
• Dehydrohalogenation called dehydrochlorination in the case where -Cl is the leaving halogen atom, is carried out by mixing with a certain base, at a certain concentration, under certain temperature conditions and for a certain period of time so as to promote elimination of halogen -Z and avoid elimination of -F.
• the base must be a sufficiently strong base to be able to eliminate -Z, without however eliminating -F.
• the base can in particular have a pKa ranging from 8 to 12, preferably ranging from 9 to 11.
• the base can advantageously be a non-aromatic and non-nucleophilic tertiary amine such as triethylamine.
• the base for example triethylamine
• the base can represent from 0.01 to 2 molar equivalents relative to the number of moles of units of formula (V).
• the proportion of base for example triethylamine, is preferably adjusted so as to retain units of formula (V) within the polymer at the end of the dehydrohalogenation step.
• the base may in particular represent from 0.1 to 1 molar equivalent, or alternatively from 0.15 to 0.5 molar equivalent relative to the number of moles of units of formula (V).
• the concentration of the base, the temperature conditions of the dehydrohalogenation and the duration of the dehydrohalogenation can be adapted by a person skilled in the art to adjust the progress of the dehydrohalogenation reaction and / or limit the formation of double bonds. carbon-carbon conjugates.
• the dehydrohalogenation is carried out with a reaction progress of at least 0.1, preferably with a reaction progress of at least 0.2.
• the step of reacting the initial polymer with the base can be followed by a step of removing the base which is in excess.
• the dehydrohalogenation is carried out so as to obtain a proportion of conjugated carbon-carbon double bonds relative to the total number of carbon-carbon double bonds less than or equal to 10%, or less than or equal to 9%, or less than or equal to 8%, or less than or equal to 7%, or less than or equal to 6%, or less than or equal to 5%, or less than or equal to 4%, or less than or equal to 3% , or less than or equal to 2%.
• the dehydrohalogenation is carried out so as to obtain a proportion of conjugated carbon-carbon double bonds relative to the total number of carbon-carbon double bonds less than or equal to 1%, or less than or equal to 0.1%, or tending towards 0.
• the dehydrohalogenation step can in particular be carried out at a temperature ranging from 20 to 80 ° C, preferably from 30 to 60 ° C, for a period ranging frome 1 to 10 hours, preferably from 2 to 8 hours.
• the product resulting from the dehydrohalogenation can be purified and / or be formulated in a composition comprising it, such as for example an ink, or be shaped to form an object, such as for example a film.
• the polymer according to the invention can be formulated in a composition.
• the composition comprises a single or alternatively a mixture of polymers according to the invention.
• the composition can comprise at least one polymer according to the invention and at least one liquid vehicle of said at least one polymer.
• This composition commonly called “ink”
• the liquid vehicle is a solvent.
• this solvent is an aprotic polar solvent, which can in particular be chosen from: dimethylformamide; dimethylacetamide; dimethylsulfoxide; ketones, especially acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclopentanone; furans, in particular tetrahydrofuran; esters, in particular methyl acetate, ethyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether acetate; carbonates, in particular dimethylcarbonate; phosphates, in particular triethylphosphate, or mixtures thereof.
• the total mass concentration of polymers in the liquid vehicle can be in particular from 0.1 to 30%, preferably from 0.5 to 20%.
• the composition may comprise one or more polymers other than those of the invention and also exhibiting an electrocaloric effect of interest.
• the composition may comprise one or more ferroelectric polymers or ferroelectric relaxer polymers not having a carbon-carbon double bond.
• the composition can in particular comprise the initial polymer.
• the composition may comprise one or more polymers other than those of the invention, possessing in particular polar or reactive functions making it possible to improve the adhesion of the composition to a given substrate.
• the composition may optionally comprise one or more additives, in particular chosen from agents for modifying the surface tension, agents for modifying the rheology, agents for modifying the caloric capacity, agents for modifying the resistance to aging, agents modifying the temperature. adhesion, pigments or dyes, flame retardants or even crosslinking aid additives.
• composition may optionally comprise fillers, in particular nanofillers, such as strontium barium titanate (BST) nanowires.
• BST strontium barium titanate
• the polymer according to the invention has, according to at least certain embodiments, sufficient mechanical properties to enable it to be able to be shaped in the form of a film.
• the film can be prepared using the polymer according to the invention or a composition comprising it, for example by applying ink to a substrate or hot melt extrusion or compression.
• the substrate may be of any nature and in particular consist of one or more layers of glass or metal (s) or organic (in particular polymeric).
• the film can optionally be stretched if necessary. Stretching (when performed) is preferably performed at a rate of at least 10% to 700%.
• the film may in particular have a stretch rate of at least 150%, or at least 200%, or at least 250%, or at least 300%, or at least 350% or d 'at least 400%.
• the stretch ratio is the ratio of the area of the film after stretching to the area of the film before stretching.
• the films can also, after having been optionally stretched, be annealed, that is to say be heated to a temperature ranging from 70 ° C to 140 ° C, preferably ranging from 100 ° C to 120 ° C, for several hours, then cooled. . Stretching, like annealing, most often makes it possible to increase its crystallinity as well as its dielectric strength.
• the invention makes it possible to obtain films with a thickness greater than or equal to 0.1 micrometer.
• their thickness is advantageously from 1 micrometers to 100 micrometers.
• these thicknesses the smallest thicknesses may be preferred so as not to have to generate excessively high voltages.
• films of thickness from 1 to 50 micrometers and even from 1 to 10 micrometers are particularly preferred.
• Electrodes can be deposited on the film, in particular by metallization or by depositing a conductive material (silver, copper, conductive polymer, silver nanowires, carbon black, CNT, etc.).
• a conductive material silver, copper, conductive polymer, silver nanowires, carbon black, CNT, etc.
• the film prepared from the polymer according to the invention can be a layer of a multilayer film, the other layers possibly comprising a polymer according to the invention, of the same composition or of different composition, another polymer. or a non-polymeric material.
• the polymer according to the invention can be used in a heat transfer system.
• the heat transfer system comprises the polymer according to the invention, in particular in the form of a film.
• the film is suitable for being in thermal contact with a load to be cooled and / or a load to be heated and / or a heat transfer fluid.
• the system also includes a voltage source for application to the plate.
• the heat transfer system can remove heat or provide heat to another device, such as an electrical or electronic component.
• the polymer according to the invention can be used in a thermal energy recovery system.
• the polymer according to the invention can also be used in an energy storage system, in particular a capacitor, an organic transistor, or an electrostatic clutch. Because of its electroactive properties, in particular ferroelectric or ferroelectric relaxer, the polymer according to the invention can also be used in actuators (for haptics, microfluidics, loudspeakers, etc.).
• Figure 1 shows a test bench 1 used to measure the electrocaloric performance of polymers as a function of temperature.
• FIG. 2 represents a typical temperature variation of a plate 2 in a test bench 1 during the application of a square electric field of height DE.
• DE is the maximum amplitude of the applied electric field and is expressed in volt / meter (V / m).
• the temperature variation peak, DT, comparable to an adiabatic temperature variation is expressed in Kelvin (K).
• K Kelvin
• the x-axis shown corresponds to time in seconds (s).
• FIG. 3 represents the 1 H liquid NMR spectrograms, measured using a Bruker Advance DPX 400 MHz apparatus, of comparative example 1 and examples 1 to 5.
• the abscissa axis represented corresponds to the chemical shift ⁇ H in ppm.
• FIG. 4 represents the RAMAN spectrograms normalized with respect to the vibration band corresponding to -CF2- between 775 and 950 cm 1 of the terpolymers P (VDF-TrFE-CTFE) unmodified (Comp. Ex.1) and modified (Ex. .1 to Ex. 5).
• the x-axis corresponds to the wave number in cm 1 and the y-axis to the relative intensity.
• FIG. 5 represents the RAMAN spectrograms normalized with respect to the vibration band corresponding to -CF2- between 775 and 950 cm 1 of the terpolymers P (VDF-TrFE-CFE) unmodified (Comp. Ex. 2) and modified ( Comp. Ex. 3 and Ex. 6-7).
• the x-axis corresponds to the wave number in cm 1 and the y-axis to the relative intensity.
• Figure 6A represents the adiabatic temperature variation DTEO measured on a test bench such as that of Figure 1, at a measurement temperature of 25 ° C as a function of the maximum amplitude of the applied electric field (expressed in MV / m), for the P (VDF-TrFE-CTFE) not modified according to Example Comparison 1 (bottom curve) and for a P (VDF-TrFE-CTFE) modified according to Example 4 (top curve).
• Figure 7A represents the variation in adiabatic temperature ATEC measured on a test bench such as that of Figure 1, at a measurement temperature of 25 ° C as a function of the maximum amplitude of the applied electric field (expressed in MV / m), for the P (VDF-TrFE-CFE) unmodified according to Comparative Example 3 (bottom curve) and for a P (VDF-TrFE-CFE) modified according to Example 8 (top curve).
• FIG. 8 represents the relative dielectric permittivity as a function of the measurement temperature of films annealed for 1 hour at 110 ° C of the polymers according to Examples 1 to 5 and of Comparative Example 1.
• the abscissa axis corresponds to the temperature in ° C and the y-axis to the relative dielectric permittivity.
• FIG. 9 represents the polarization as a function of the electric field at 25 ° C of films annealed for 1 h at 110 ° C of the polymers according to Examples 1 -5 and according to Comparative Example 1.
• the abscissa axis corresponds to the electric field in MV / m and the y-axis with polarization in pC / cm 2 ).
• [Figure 10] represents the relative dielectric permittivity as a function of the temperature of films annealed for 1 h at 110 ° C of the polymers according to Examples 7 and and Comparative Examples 2 and 3.
• the abscissa axis corresponds to the temperature in ° C and the ordinate axis to the relative dielectric permitivity.
• [Figure 11] represents the polarization as a function of the electric field at 25 ° C of films annealed 1 h at 110 ° C of the polymers according to Example 8 and according to Comparative Example 2.
• the abscissa axis corresponds to the field electrical in MV / m and the y-axis with polarization in pC / cm 2 ).
• Figure 12 represents superimposed infrared spectrograms of the polymer according to Example 3 after storage at 110 ° C for 1 h, 5 h and 3 days.
• the x-axis corresponds to the wave number in cm 1 and the y-axis to the normalized absorbance.
• a polymer film 21 is prepared by blade coating from a solution of 100 mg / mL in a solvent in which it is soluble.
• the solvent used was cyclopentanone.
• the solution is prepared at room temperature (25 ° C.) with magnetic stirring for 24 h.
• Films 21 of 14 ⁇ m are deposited on a substrate 22.
• the substrate 22 is made of PET, has a thickness of 50 ⁇ m and has been previously metallized (10 nm of Cr and 100 nm of Ag).
• the upper electrodes 23 are evaporated. Annealing is then carried out at 105 ° C. for 12 h under vacuum.
• a plate 2 comprising a film of the polymer to be characterized is obtained.
• the low-field dielectric data are obtained with a “Solartron SI 1260” device, marketed by the Solartron Analytical company, fitted with the “Solartron 1296 dielectric interface” and a “TP94 Linkam” enclosure, marketed by the Company. Linkam Scientific, for temperature control. The measurements are carried out at 1 kHz at different temperatures.
• the polarization curves (electrical displacement (D) as a function of the electric field (E)) are produced with an "aixACCT TF Analyzer 2000” device, marketed by the company aixACCT Systems, equipped with a high voltage amplifier "Treck 20 / 20C -HS ”, marketed by the company Treck.
• the electrocaloric performances are measured as a function of the temperature and of the electric field applied from a test bench 1 as shown in Figure 1.
• the test bench comprises the plate 2, placed on a thermocouple 3, it - even placed on a heat sink 4 (heatsink), itself placed on a heating means 5.
• the thermocouple 3 measures the temperature of the surface of the plate 2 and the temperature variations of the plate 2.
• the heat sink heat 4 under the thermocouple 3 ensures the best possible thermal contact between the heating means 5, the thermocouple 3 and the film 21.
• the heating means 5 allows the system to be thermostated to a measurement temperature. A temperature ramp of 10 ° C / min can be applied.
• a square-wave electric field with a minimum value equal to 0 and a maximum value + DE, with a period equal to about 90 s, is applied, causing an extremely rapid variation in temperature, the peak of this variation, DT, being able to be measured and corresponding to what is designated by adiabatic temperature variation in the invention.
• VDF-TrFE-CTFE terpolymer P having an average molar mass by weight estimated between 400,000 and 600,000 g / mol, of molar composition 62/30/8, were dissolved in 100 mL of dimethyl sulfoxide (DMSO ) in a 250 mL flask. After dissolution, triethylamine (TEA) is added with magnetic stirring. After the reaction, the polymer is purified by precipitation in water, dried in vacuo, dissolved in acetone and precipitated in a 60/40 ethanol / water mixture by mass. The product is dried under vacuum at 40 ° C. for 12 h.
• DMSO dimethyl sulfoxide
• TAA triethylamine
• reaction parameters (amount of TEA, time and temperature) are shown in Table 1.
• the number of TEA equivalents is calculated relative to the number of -Cl atoms in the terpolymer.
• the level of DB double bond, expressed as a molar percentage, was evaluated from the 1 H liquid NMR spectra (see FIG. 3) by integration of the signal according to the following relationship:
• a terpolymer P (VDF-TrFE-CFE) having an average molar mass by weight estimated between 400,000 and 600,000 g / mol, of molar composition 66/27/7 are dissolved in 100 mL of DMSO in a flask of 250 mL. After dissolution, triethylamine (TEA) is added with magnetic stirring. After the reaction, the polymer is purified by precipitation in water, dried under vacuum, dissolved in acetone and precipitated in a 60/40 mass mixture of ethanol / water. The product is dried under vacuum at 40 ° C for 12 h.
• the various reaction parameters (amount of TEA, time and temperature) are shown in Table 2. The number of TEA equivalents is calculated relative to the number of -Cl atoms in the terpolymer. The number of double bonds is calculated as already explained from the 1 H liquid NMR spectra.
• the electrocaloric properties in particular of the value of the temperature variation adiabatic at a given measurement temperature and under an electric field of given maximum amplitude, polymers comprising unconjugated double bonds according to the invention (ex. 7) are better than those of a polymer of similar structure but comprising conjugated double bonds (eg comp. 1).
• the ATEC values vary little over the measurement temperature interval: a variation of less than 20% is observed for measurement temperatures ranging from 25 ° C to 50 ° C.
• the polymers having unconjugated double bonds according to the invention have a higher dielectric constant (examples 1-5; 6-7) than those of a polymer of similar structure but not comprising a double bond (Ex. Comp.1; Ex. Comp. 2) or comprising conjugated double bonds (Ex. Comp.3).
• the polymers having unconjugated double bonds according to the invention are ferroelectric relaxer polymers.
• the melting temperature and the enthalpy of fusion were measured according to standard ISO 11357-3: 2018, in second heating, with a heating ramp of 10 ° C / min.
• the valence vibration band at 1700 cnr 1 for the polymer according to Example 3, corresponding to the carbon-carbon double bonds, is still present after 3 days of storage at 110 ° C, indicating a good thermal stability of the polymer.

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