WO2002083780A1 - Composites a constante dielectrique elevee constitues d'un oligomere metallophtalocyanine et d'un copolymere poly(vinylidene-trifluoroethylene) - Google Patents

Composites a constante dielectrique elevee constitues d'un oligomere metallophtalocyanine et d'un copolymere poly(vinylidene-trifluoroethylene) Download PDF

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Publication number
WO2002083780A1
WO2002083780A1 PCT/US2002/011454 US0211454W WO02083780A1 WO 2002083780 A1 WO2002083780 A1 WO 2002083780A1 US 0211454 W US0211454 W US 0211454W WO 02083780 A1 WO02083780 A1 WO 02083780A1
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Prior art keywords
polyvinylidene fluoride
composite
dielectric constant
fluoride
tetrafluorethylene
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PCT/US2002/011454
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English (en)
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WO2002083780A8 (fr
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Qiming Zhang
Haisheng Xu
Zhong Yang Cheng
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The Penn State Research Foundation
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Priority claimed from US10/108,231 external-priority patent/US6787238B2/en
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Publication of WO2002083780A1 publication Critical patent/WO2002083780A1/fr
Publication of WO2002083780A8 publication Critical patent/WO2002083780A8/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0091—Complexes with metal-heteroatom-bonds
    • 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

Definitions

  • the present invention relates to composite materials with elevated electric field induced strain levels, elevated dielectric constants, and having flexible mechanical properties.
  • the materials of the invention comprise a polymer matrix and high dielectric constant organic material.
  • electroactive polymers are of
  • the room temperature dielectric constant of poly(vinylidene-trifluoroethylene) copolymer P(VDF-TrFE) can be increased to about 50, a marked improvement compared with the current available polymers. Elevated dielectric constant PVDF-based terpolymer materials are also developed. However, how to raise the dielectric constant to much higher level without stiffening the polymers is still a challenge. For example, using high dielectric constant ceramics as the filler, the room temperature dielectric constant of the so-called 0-3 composites (ceramic powder polymer matrix composites) can reach 300.
  • the present invention shows that by making use of the organic solids which possess high dielectric permittivity through the mechanism of nomadic polarization as the fillers, at room temperature and 100 Hz, a composite material with dielectric constant more 1 ,000 and dielectric loss less than 0.5 can be realized.
  • the composite film is also mechanically flexible with the elastic modulus nearly the same as that of the polymer matrix.
  • the composite films which elastic modulus is 0.6 GPa also exhibit high strain ( ⁇ 2%) under an electric field of 13 MV/m, a marked improvement compared with other electroactive polymers.
  • One of the uniqueness of the composite is its mechanical properties which remain very much the same as those of the polymer matrix. Even for a composite with 55 wt% CuPc (the volume fraction of CuPc in the composite is also in the similar range), the composite film is still flexible with a Young's modulus of 1.2 GPa at room temperature. Furthermore, it has been demonstrated that in a composite with 40 wt% CuPc filler and relaxor P(VDF-TrFE) matrix, a strain of near 2 % can be induced by a field of 13 MV/m while the composite modulus is 0.6 GPa. The strain is proportional to the square of the applied electric field. In addition to the simple composite approach, other approaches to achieve high dielectric constant with metallophthalocyanine are also discussed.
  • Fig. 1 shows the molecular structure of copper-phthalocyanine
  • Fig. 2a and Fig 2b are graphs of the dielectric constant and dialectric loss, respectively, of composite films of the invention measured at room temperature. The films have different weight percentage of CuPc filler.
  • Fig. 3 is a graph of the dielectric properties of composites of the invention having 55 wt% CuPc measured at room temperature in the frequency range from 1 to 100 Hz.
  • Figure 4 shows the induced strain of a composite with 40 wt% CuPc filler and the relaxor ferroelectric P(VDF-TrFE) copolymer matrix measured at room temperature and 1 Hz applied field
  • Fig. 5a and Fig. 5b are graphs of the dielectric constant and dielectric loss, respectively, of the composite with 55 wt% CuPc filler at different frequencies.
  • Fig. 6 shows the molecular structure of CIAn/CI 4 and Pyrene/0- iodoBA.
  • the present invention is directed to a polymer based material with preferred, but not necessarily limited to, dielectric constant of higher than 400 while still retaining the flexibility of the polymers, with elastic modulus in the range of polymers ( ⁇ 1 GPa).
  • This class of material has been shown to exhibit high electromechanical properties under low applied field ( ⁇ 20 V/ ⁇ m).
  • PVDF-TrFE modified poly(vinylidene fluoride-trifluoroethylene)
  • Metallophthalocyanine oligomers such as copper-phthalocyanine (CuPc) have been shown to exhibit high dielectric constant (>1,000) and high dielectric loss while elastically is relatively compliant.
  • CuPc copper-phthalocyanine
  • One of the problems with CuPc is the poor processibility.
  • PVDF-TrFE poly(vinylidene fluoride-trifluoroethylene) based polymers, through proper modifications such as high energy irradiation and terpolymers with selected ter-monomers, exhibit relatively high room temperature dielectric constant (>50) which is by far the highest among the all polymers known and high electrostrictive strain.
  • PVDF-TrFE as the matrix material can also provide good processing capability which also has relatively high dielectric constant and high field induced strain.
  • VDF-TrFE Modified poly(vinylidene fluoride-trifluoroethylene) based polymers.
  • Ferroelectric polyvinylidine fluoride polymer that has been processed to exhibit an electrostrictive strain of 4% or more when an electric field strength of 50 megavolts per meter or greater is applied thereacross, has been developed .
  • the processing of the polymer preferably involves subjecting it to either electron beam radiation or gamma radiation.
  • the polyvinylidine fluoride polymer is selected from the group of: polyvinylidine flouride, polyvinylidine flouride-trifluoroethylene P(VDF-TrFE), polyvinylidine tetrafluoroethylene P(VDF-TFE), polyvinylidine trifluoroethylene hexafluoropropylene P(VDF-TFE-HFE) and polyvinylidine hexafluoropropylene P(VDF-HFE).
  • Such ferroelectric polymers can be prepared by a process comprising the steps of annealing a polyvinylidine fluoride polymer at a temperature at or about 130°C to about 140° C for about 16 hours; and irradiating said polyvinylidine fluoride polymer in an oxygen free atmosphere with an energy in the range from about 500 KeV to about 3 MeV to produce a relaxor ferroelectric polymer which exhibits an electrostrictive strain, at room temperature, of 3% or more when an electric field gradient of about 100 megavolts per meter or greater is applied thereacross.
  • the irradiating step is preferably at a temperature from about 25°C to about 120°C.
  • Relaxor ferroelectric polymers are preferably selected from the group consisting of: polyvinylidine fluoride homopolymer, polyvinylidine fluoride-trifluoroethylene P(VDF-TrFE), polyvinylidine fluoride-tetrafluoroethylene P(VDF-TFE), polyvinylidine- fluoride trifluoroethylene-hexafluoroproplylene (VDF-TFE-HFE) and polyvinylidine fluoride-hexafluoropropylene P(VDF-HFE).
  • the molar percentages of polyvinylidine fluoride/trifluoethylene are from about 30/70 to about 75/25 mol%.
  • Preferred relaxor ferroelectric polymers of electrostrictive polyvinylidine fluoride exhibit an electrostrictive strain, at room temperature, of 3% or more when an electric field gradient of 100 megavolts per meter or greater is applied thereacross.
  • Such relaxor ferroelectric polymers generally exhibit the following properties: a dielectric constant, at room temperature, of greater than 40 at 1 kHz or higher; and an electric energy density, at room temperature, of greater than 0.3 Joules/cm 3 or 160 Joules/kg, which enables avoidance of breakdown at applied field levels thereacross of at least 350 megavolts per meter.
  • Polymers exhibiting high room temperature dielectric constant and high strain.
  • Polymers are prepared by polymerizing a mixture of three monomers comprising: at least one monomer of vinylidene-fluoride; at least one monomer selected from the group consisting of trifluorethylene and tetrafluoroethylene; and at least one monomer selected from the group consisting of tetrafluorethylene, vinyl fluoride, perfluoro (methyl vinyl ether); bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, and hexafluoroethylene.
  • Polymers of the invention exhibit an electrostrictive strain, at room temperature, of 3% or more when an electric field gradient of 100 megavolts per meter or greater is applied thereacross; exhibit a dielectric constant, at room temperature, of 40 or higher at 1 kHz; and exhibit an elastic energy density, at room temperature, of 0.3 joules/cm 3 or higher, or any combinations thereof.
  • terpolymers may be prepared by a process comprising: polymerizing a mixture of three monomers comprising at least one monomer of vinylidene-fluoride; at least one monomer selected from the group consisting of trifluorethylene and tetrafluoroethylene; and at least one monomer selected from the group consisting of tetrafluorethylene, vinyl fluoride, perfluoro (methyl vinyl ether), bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, and hexafluoroethylene; stretching said polymer greater than its original length; and thereafter annealing said polymer at a temperature below its melting point, wherein said polymer exhibits an electrostrictive strain, at room temperature, of 3% or more when an electric field gradient of 100 megavolts per meter or greater is applied thereacross, exhibits a dielectric constant, at room temperature, of 40 or higher at 1 kHz, and exhibits an elastic energy density, at room temperature, of 0.3
  • Ter-polymers include, but are not necessarily limited to, polyvinylidene fluoride-trifluorethylene-chlorofluoroethylene P(VDF-TrFE- CFE), polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene P(VDF-TrFE-CTFE), polyvinylidene fluoride-tetrafluoroethylene- chlorotrifluoroethylene, polyvinylidene fluoride-trifluorethylene- hexafluoroethylene , polyvinylidene fluoride-tetrafluorethylene- hexafluoroethylene, polyvinylidene fluoride-trifluorethylene- tetrafluoroethylene, polyvinylidene fluoride-tetrafluorethylene- tetrafluoroethylene, polyvinylidene fluoride-tetrafluorethylene- tetrafluoroethylene, polyvinylidene fluoride-trifluorethylene-viny
  • a strain which is proportional to E 2 of 0.3% can be obtained under a field of 1 V/ ⁇ m from the composite with 55wt% of CuPc.
  • the composite film is flexible with a elastic modulus 1.2 GPa.
  • the strain level can be much higher.
  • a strain of near 2% is induced under a field of 13 MV/m.
  • the elastic modulus of the composite is 0.6 GPa.
  • a preferred high dielectric constant semiconductor organic solid used in this invention is a metallophthalocyanine oligomer, copper- phthalocyanine (CuPc) whose molecular structure is shown in Figure 1.
  • the CuPc has a room temperature dielectric constant at 100 Hz of more than 1 ,000 and the dielectric loss is also high. Because of the nomadic polarization mechanism (delocalized electrons lead to the space charge phenomenon), these oligomers suffer high dielectric loss. In addition, they are brittle and difficult to process.
  • the P(VDF-TrFE) based relaxor ferroelectric polymers which have a relatively high room temperature dielectric constant ( ⁇ 40) after irradiation treatment, is chosen as the matrix. Compared with CuPc, the copolymer has very low dielectric loss and as the matrix, it can provide an insulation layer to CuPc particles to significantly reduce the dielectric loss in the composite.
  • Copper-phthalocyanine oligomer was synthesized by solution method. Copper sulfate pentahydrate, pyromellitic dianhydride urea, ammonium chloride, and ammonium molybdate were ground together and then placed in a three-necked flask with a thermometer, condenser, and mechanical stirrer. Nitrobenzene was used as solvent and the temperature of reaction solution maintained at 185°C for 12h. The as-synthesized solid materials was finely ground and washed with methanol to remove nitrobenzene completely. The powder was boiled with 2N hydrochloric acid saturated with sodium chloride and filtered after cooling to room temperature. The product was neutralized by 2N potassium hydroxide solution containing sodium chloride at 90°C. After centrifugation, the product was dried at room temperature under vacuum.
  • the P(VDF-TrFE) based relaxor ferroelectric polymer either the high energy irradiated copolymer or non-irradiated terpolymer, was used for the polymer matrix.
  • the composite film was prepared by solution casting method. P(VDF-TrFE) copolymer was first dissolved in dimethyl formamide (DMF), and then a proper amount of CuPc powder was added into the solution. After stirring for 12h at room temperature, the suspension was then poured onto a glass plate and dried at 70°C for 4h in air, followed by further drying under vacuum at the same temperature for additional 12h to remove any remaining traces of the solvent. Composites with weight percentage of the CuPc from 30-80% were prepared.
  • the free standing composite films of CuPc oligomer and P(VDF- TrFE) copolymer with different weight percentage of CuPc from 30% to 80% were prepared. Since the density of CuPc is close to that of P(VDF- TrFE) copolymer, the wt% is also close to the volume % of the CuPc in the composite.
  • the films prepared are flexible and the Young's modulus of the composite with 55 wt% CuPc was measured to be 1.2 GPa at 25 °C, which is close to the Young's modulus of the polymer matrix. Therefore, the 0-3 composites developed here have very attractive mechanical properties compared with the 0-3 composites made of ceramic fillers.
  • the dielectric constant of the composite with 55 wt% CuPc was also characterized at lower frequencies (1 Hz to 100 Hz) and the result is shown in Figure 3.
  • the dielectric constant increases continuously as the frequency decreases, and at 1 Hz it reaches 3,000 although the dielectric loss also becomes quite high ( ⁇ 3).
  • the high dielectric constant of CuPc can be explained in terms of the long-range electron orbital delocalization, also called nomadic polarization.
  • Metallophthalocyanine oligomers are highly conjugated and have a large planar structure.
  • the ⁇ -electrons are completely delocalized over the entire molecule.
  • the nomadic polarization of CuPc still plays an important role in the composite film, especially for the composite with high percentage of CuPc.
  • the composite prepared here also exhibits a high field induced strain, which is proportional to the square of the applied electric field E.
  • the temperature dependence of the low field dielectric constant and dielectric loss of the composite with 55 wt% CuPc was also investigated and the results are shown in Figure 5.
  • the data shows that over a relatively broad temperature range, the dielectric constant is quite high, especially at lower frequency, e.g., 100Hz.
  • a dielectric maximum of about 2,300 (at 100 Hz) was observed at 70°C, which is near the Curie temperature of P(VDF-TrFE) copolymer.
  • the dielectric constant is 17 at room temperature and 100 Hz and increase with temperature.
  • the copolymer exhibits a dielectric maximum, which is about 50. Therefore the dielectric constant of the composite, which is determined by copolymer and CuPc, also show a dielectric maximum. This is consistent with the results presented in Figure 5.
  • the high dielectric constant filler In addition to the metallophthalocyanine as the high dielectric constant filler, there are several other classes of high dielectric constant organic molecules, whose polarization is also based on delocalized electrons, which can also be used as filler: CIAn/CI 4 Pa and Pyrene/o- iodoBA, whose molecular structures are illustrated in Figure 6.
  • P(VDF-TrFE) copolymer as the matrix
  • other copolymers with dielectric constant higher than 20 can also be used as the matrix of the composites such as the high energy irradiated P(VDF-TrFE) and P(VDF-TFE) copolymers, the PVDF based terpolymers.
  • metallophthalocyanine as the high dielectric constant filler
  • CuPc will be directly incorporated into polymer chains at the molecular level.
  • CuPc oligomer is grafted with soft polymer chain such as polyethylene glycol (PEG).
  • PEG polyethylene glycol
  • the dielectric property and mechanical property will depend on how many -COOH groups in CuPc are reacted with PEG and the molecular weight of PEG.
  • the grafted CuPc can be used directly as composite (liquid crystal polymer type).
  • CuPc can be directly grafted to PVDF-TrFE polymer chain.
  • PVDF-TrFE has a relatively high dielectric constant compared with other polymers.
  • the reaction of PVDF- TrFE copolymer in aqueous NaOH with the use of phase transfer catalyst results in dehydroflurination.
  • the copolymers with double bond units are treated further with peroxidate to form hydroxyl (-OH) group.
  • PVDF- TrFE copolymer with -OH group is then grafted on CuPc by means of esterification.
  • Another approach addresses the issue of raising the breakdown strength of the composites in which the CuPc powder (or other high dielectric constant semiconductor organic molecular solids) is physically mixed with the polymer matrix.
  • small crystallites for example, nano-size CuPc fillers
  • suitable surfactants can be added to the composites to improve the dispersion of CuPc (or other high dielectric constant semiconductor organic molecule solids) in the polymer matrix.
  • a blocking layer approach such as one layer of P(VDF-TrFE) based electrostrictive polymer (the terpolymer or high-energy electron irradiated copolymer)
  • a blocking layer such as one layer of P(VDF-TrFE) based electrostrictive polymer (the terpolymer or high-energy electron irradiated copolymer)
  • the breakdown field of a thin layer of irradiated P(VDF-TrFE) polymer has been measured to be above 300 MV/m for a 20 ⁇ m thick film.
  • the PVDF layer thickness can be ⁇ 0.1 ⁇ m.
  • Such a thin layer will have a much higher breakdown field since the breakdown field in inversely proportional to the film thickness due to the avalanche nature of the electric breakdown process.
  • this layer will not affect the dielectric constant of the whole composite very much.
  • the effect of such a blocking layer is very much similar to the principle of the corona poling in which a field much higher than the breakdown filed of the sample to be poled can be applied without causing breakdown because of the limit in the current available.

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Abstract

Nouvelles matières composites possédant un niveau amélioré de contrainte induite par des champs électriques, des constantes électriques améliorées et des propriétés mécaniques avantageuses, destinées à être utilisées dans des dispositifs électriques.
PCT/US2002/011454 2001-04-13 2002-04-12 Composites a constante dielectrique elevee constitues d'un oligomere metallophtalocyanine et d'un copolymere poly(vinylidene-trifluoroethylene) WO2002083780A1 (fr)

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US28375501P 2001-04-13 2001-04-13
US60/283,755 2001-04-13
US10/108,231 US6787238B2 (en) 1998-11-18 2002-03-27 Terpolymer systems for electromechanical and dielectric applications
US10/108,231 2002-03-27

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008041998A1 (fr) 2006-10-03 2008-04-10 The Penn State Research Foundation Fluoropolymères à terminaisons fonctionnalisées présentant de bonnes propriétés électriques et une bonne réactivité chimique
EP3792304A1 (fr) * 2019-09-10 2021-03-17 Solvay SA Compositions et films comprenant un (co)polymère de fluorure de vinylidène et un composé aromatique, leur préparation et leurs utilisations

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5409557A (en) * 1992-10-07 1995-04-25 Xerox Corporation Method of manufacturing a reinforced seamless intermediate transfer member
US5641879A (en) * 1994-09-23 1997-06-24 Ciba-Geigy Corporation Phthalocyanines substituted by phosphorus-containing groups

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5409557A (en) * 1992-10-07 1995-04-25 Xerox Corporation Method of manufacturing a reinforced seamless intermediate transfer member
US5641879A (en) * 1994-09-23 1997-06-24 Ciba-Geigy Corporation Phthalocyanines substituted by phosphorus-containing groups

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008041998A1 (fr) 2006-10-03 2008-04-10 The Penn State Research Foundation Fluoropolymères à terminaisons fonctionnalisées présentant de bonnes propriétés électriques et une bonne réactivité chimique
US7842390B2 (en) 2006-10-03 2010-11-30 The Penn State Research Foundation Chain end functionalized fluoropolymers having good electrical properties and good chemical reactivity
EP3792304A1 (fr) * 2019-09-10 2021-03-17 Solvay SA Compositions et films comprenant un (co)polymère de fluorure de vinylidène et un composé aromatique, leur préparation et leurs utilisations

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