WO2019073012A1 - Composition comprenant des nanofils d'argent et au moins un polymère fluoré - Google Patents

Composition comprenant des nanofils d'argent et au moins un polymère fluoré Download PDF

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WO2019073012A1
WO2019073012A1 PCT/EP2018/077808 EP2018077808W WO2019073012A1 WO 2019073012 A1 WO2019073012 A1 WO 2019073012A1 EP 2018077808 W EP2018077808 W EP 2018077808W WO 2019073012 A1 WO2019073012 A1 WO 2019073012A1
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solvent
composition
composition according
film
fluorinated polymer
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PCT/EP2018/077808
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Frédéric COLBEAU-JUSTIN
Olivier SANSEAU
Sylvie Ghiringhelli
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Rhodia Operations
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys

Definitions

  • Composition comprising silver nanowires and at least one fluorinated polymer
  • the present invention concerns a composition comprising at least one fluorinated polymer and silver nanowires coated with at least one metal oxide and a process for preparing such composition. It also pertains to films comprising said composition and to processes for preparing these films.
  • Polymer composites having high dielectric permittivity can be useful in many applications such as capacitors, actuators, sensors or energy harvesting devices.
  • polymers are used as matrix where they bring excellent thermal and mechanical properties while fillers, which are dispersed in the polymer matrix, bring functionalities.
  • Polymer matrix in composite is also responsible for high flexibility and high processability.
  • conductive nano-objects having low percolation threshold because of their high aspect ratio is a strategy to achieve high dielectric permittivity materials.
  • conductive fillers such as metal nanowires can also increase dielectric loss and leakage current because of forming a conduction network.
  • dielectric permittivity and dielectric loss of a material are related to each other by the dissipation factor tan ⁇ also named dielectric loss tangent:
  • A.Bruna da Silva et al. in Polymer, 2014, vol. 55, p. 226-234 describe composites of copper nanowires and polyvinylidene fluoride (PVDF) with high dielectric permittivity and low dielectric loss.
  • the composite is prepared by mixing at room temperature a solution of PVDF in DMF with a dispersion of Cu nanowires in DMF.
  • the dielectric loss of the composite significantly increases with the copper nanowires content and the dissipation factor tan ⁇ is rather high.
  • dielectric permittivity values are very limited in some domains of frequency sweep.
  • WO2014/028027 Al discloses the injection molding of polyphenylene sulfide with silica coated silver nanowires. Resulting composites have high thermal conductivity. None is said about dielectric properties of the material.
  • Materials having high dielectric permittivity and low dielectric loss are highly desirable for manufacturing devices having low electrical consumption and/or having high electrical response to mechanical stimuli and/or having high mechanical response to electrical stimuli e.g. for electromechanical applications.
  • sensors in particular haptic sensors
  • actuators in particular haptic actuators
  • energy harvesting devices Low electrical consumption is economically valuable because it spares resources and also because it increases the shelf life of the device by avoiding over-heating during operating.
  • Materials having high dielectric permittivity and low dielectric loss are also highly desirable for manufacturing energy storage devices such as capacitors.
  • compositions combining the properties above described having high thermal and chemical stability.
  • high processability of such compositions There is also a need for high processability of such compositions.
  • fluorinated polymer polymer comprising repeat units derived from at least one fluorinated monomer.
  • fluorinated monomer ethylenically unsaturated monomer comprising at least one fluorine atom.
  • the fluorinated polymers suitable are chosen among vinylidene fluoride homopolymers or copolymers which provide advantageously high chemical resistance.
  • Vinylidene fluoride copolymers comprise generally at least 50 % by moles, very often at least 60 % by moles, preferably at least 75 % by moles, more preferably at least 85 % by moles and possibly at least 95 % by moles of repeat units derived from vinylidene fluoride.
  • Vinylidene fluoride copolymers comprise generally from 0 to 15 % by moles of repeat units derived from monomers selected from the list consisting of vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, hexafluoroisobutylene, pentafluoropropene, 3,3,3- trifluoropropene, perfluoromethylvinylether and mixtures thereof.
  • Vinylidene fluoride copolymers may also comprise repeat units derived from at least one (meth)acrylic monomer.
  • (Meth)acrylic monomers include monomers having the formula (I) thereafter :
  • Ri, R 2 and R 3 are equal to or different from each other, are independently selected from hydrogen atom and a C 1 -C4 group, and
  • R4 is selected from hydrogen atom and Ci-Ci 2 group optionally comprising at least one heteroatom.
  • Non limitative examples of (meth)acrylic monomers are notably acrylic acid, methacrylic acid, hydroxyethyl (meth)acrylate,
  • the (meth)acrylic monomer is preferably selected among:
  • the repeat units derived from the (meth)acrylic monomer are comprised in the copolymer in an amount of preferably from 0% to 15 % by moles and more preferably from 0% to 10 % by moles.
  • TrFE is trifluoroethylene
  • CTFE is chlorotrifluoroethylene
  • HFP is hexafluoropropylene
  • the suitable fluorinated polymer is a fluoropolymer [polymer (F)] comprising:
  • VDF vinylidene fluoride
  • TroFE trifluoroethylene
  • R'i, R' 2 and R' 3 are independently selected from a hydrogen atom and a Ci-C 3 hydrocarbon group, and - R'OH represents a hydrogen atom or a Ci -C 5 hydrocarbon moiety comprising at least one hydroxy 1 group.
  • the polymer (F) of the invention comprises preferably from 15% to 48% by moles, more preferably from 16% to 45% by moles, even more preferably from 17% to 40% by moles of recurring units derived from trifluoroethylene (TrFE).
  • the (meth)acrylic monomer [monomer (MA)] preferably complies with formula (III) here below:
  • R"i and R" 2 are independently selected from a hydrogen atom and a C1-C3 hydrocarbon group, preferably R"i and R" 2 being hydrogen atoms,
  • - R"OH represents a hydrogen atom or a C1-C5 hydrocarbon moiety comprising at least one hydroxy 1 group.
  • Non- limitative examples of (meth)acrylic monomers (MA) notably include acrylic acid, methacrylic acid, hydroxyethyl(meth)acrylate,
  • the monomer (MA) is more preferably selected from the folio wings:
  • the monomer (MA) is even more preferably acrylic acid (AA) or fry droxyethylacry late (HE A).
  • the polymer (F) of the invention may further comprise recurring units derived from one or more other fluorinated comonomers [comonomer (F)].
  • fluorinated comonomer [comonomer (F)] is hereby intended to denote an ethylenically unsaturated comonomer comprising at least one fluorine atom.
  • the comonomer (F) may further comprise one or more other halogen atoms such as chlorine, bromine and iodine atoms.
  • Non- limitative examples of suitable comonomers (F) notably include the folio wings:
  • C 2 -Cs perfluoroolefins such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP);
  • chloro- and/or bromo- and/or iodo-C 2 -C 6 fluoroolefins such as chlorotrifluoroethylene (CTFE);
  • perfluoroalkylvinylethers of formula CF 2 CFOR f i, wherein RA is a Ci-C 6 perfluoroalkyl group, such as perfluoromethylvinylether (PMVE) and perfluoropropylvinylether (PPVE);
  • PMVE perfluoromethylvinylether
  • PPVE perfluoropropylvinylether
  • the comonomer (F) is preferably free of hydrogen atoms.
  • fluorinated comonomers are chlorotrifluoroethylene (CTFE), perfluoromethylvinylether (PMVE), tetrafluoroethylene (TFE), hexafluoropropylene (H FP).
  • CFE chlorotrifluoroethylene
  • PMVE perfluoromethylvinylether
  • TFE tetrafluoroethylene
  • H FP hexafluoropropylene
  • the polymer (F) of the invention comprises typically from 2% to 20% by moles, preferably from 3% to 18% by moles, more preferably from 4% to 15% by moles of recurring units derived from said fluorinated comonomer (F).
  • the glass transition temperature of the fluorinated polymer is generally of at most 50 °C, preferably of at most 20 °C, more preferably of at most 0 °C and even preferably of at most -5 °C. Besides, the glass transition temperature of the fluorinated polymer is generally of at least -60 °C, preferably of at least -50 °C and more preferably of at least -40 °C.
  • Glass transition can be measured by differential scanning calorimetry (DSC) well known by the skilled person.
  • DSC differential scanning calorimetry
  • the silver nanowires comprised in the composition according to the invention are coated with at least one metal oxide.
  • the oxide is selected from the list consisting of titanium, zirconium, hafnium, vanadium, aluminum, gallium, indium, silicon, germanium and tin oxides and mixtures thereof.
  • the metal oxide is often selected from the list consisting of titanium, zirconium, aluminum and silicon oxides and mixtures thereof. It is preferably selected from the list consisting of silicon oxides and titanium oxides. It is more preferably silicon dioxide. In some embodiments, the metal oxide is selected from the list consisting of hafnium, vanadium, gallium, indium, germanium and tin oxides and mixtures thereof.
  • the metal oxide coating is obtained by a sol-gel process conducted in the presence of silver nanowires.
  • any commercially available silver nanowires coated with at least one metal oxide can be used in the process.
  • sol-gel process can be seen as the hydrolysis and the condensation of metal alkoxides giving a three dimensional network of metal oxides.
  • sol-gel process steps are described by L.Hench et al. in
  • the sol-gel process is generally conducted in a reaction medium
  • a reaction medium comprising a volume ratio of alcohol and water generally of at most 10/1, preferably of at most 8/1, more preferably of at most 6/1 and even more preferably at most 5/1.
  • the volume ratio of alcohol and water is generally of at least 1/5, preferably of at least 2/5, more preferably of a least 3/5 and even more preferably of at least 4/5.
  • Precursors for the metal oxides are generally titanium, zirconium, aluminum, or silicon alkoxides.
  • Precursors of silicon oxide can be but are not limited to
  • TMOS tetramethylorthosilicate
  • TEOS Tetraethylorthosilicate
  • TPOS tetraisopropylorthosilicate
  • Precursors of aluminum oxide can be but are not limited to aluminum- (isopropoxide) or aluminum-(2-butoxide).
  • Precursor of zirconium oxide can be but is not limited to zirconium- (isopropoxide) and precursors of titanium oxide can be but are not limited to titanium-(2-ethoxide) or titanium-(isopropoxide).
  • Some other precursors for the oxides are generally hafnium, vanadium, gallium, indium, germanium or tin alkoxides such as hafnium isopropoxide, vanadium (V) oxytriisopropoxide, tetraethyl orthogermanate, gallium (III) isopropoxide, indium ethoxide or tin tert-butoxide.
  • the synthesis of the metal oxide via the sol-gel process can be catalyzed by the use of an acid or a basic catalyst.
  • an acid or a basic catalyst for example, in the former case HC1 may be involved while in the latter case ammonia may be used.
  • ammonia is used as basic catalyst.
  • the sol-gel process can be performed by adding under stirring to a suspension of silver nanowires in a mixture comprising water and at least one alcohol, metal oxide precursors and catalyst, all these components being as previously described.
  • the sol-gel process can be conducted at room temperature. It is often conducted at a temperature of at least 40°C, possibly at a temperature of at least 60°C, sometimes at a temperature of at least 80°C and rarely at a temperature of at least 100°C.
  • the sol-gel process is performed using inorganic precursors.
  • Inorganic precursors for the metal oxides are generally titanates, zirconates, aluminates or silicates.
  • Inorganic precursors are generally alkali metal or earth alkaline metal titanates, zirconates, aluminates or silicates. They are preferably alkali metal, more preferably potassium or sodium and even more preferably sodium titanates, zirconates, aluminates or silicates.
  • Some other inorganic precursors for the metal oxides are generally vanadates, germanates or stannates such as potassium or sodium and preferably sodium vanadates, germanates or stannates.
  • the synthesis of the metal oxide via the sol-gel process involving inorganic precursors can be catalyzed by the use of an acid catalyst.
  • HC1 is used as acid catalyst.
  • the sol-gel process can be performed by adding under stirring to a suspension of silver nanowires in a mixture comprising water and optionally an alcohol, inorganic metal oxide precursors and catalyst, all these components being as previously described.
  • the silver nanowires coated with metal oxide are generally recovered from the reaction mixture.
  • the silver nanowires coated with metal oxide can be recovered by sedimentation resulting from centrifugation.
  • the alcohol/water supernatant can be removed and the coated nanowires isolated.
  • the coated nanowires can also be isolated by vacuum- filtering the sedimented suspension.
  • the weight ratio of metal oxide with regard to the total weight of silver nanowires coated with at least one metal oxide is generally of at least 1 wt. %, often of at least 5 wt. % and possibly of at least 10 wt. %. The ratio is generally of at most 25 wt. %, often of at most 20 wt. % and possibly of at most 15 wt. %.
  • the silver nanowires coated with at least one metal oxide suitable for the invention have generally an aspect ratio of at least 10, preferably of at least 15 and even preferably of at least 20.
  • the silver nanowires coated with metal oxide have usually an aspect ratio of at most 5000, preferably of at most 1000, even more preferably of at most 500 and the most preferably at most 200.
  • the aspect ratio is the ratio of length to width of a particle (ISO, 1999).
  • An average aspect ratio may be determined by image processing of TEM or SEM.
  • the coated nanowires can be further submitted to several dispersion- centrifugation cycles in a solvent to remove impurities.
  • impurities one can consider species involved in the sol-gel process such as alcohol, acid or base catalyst or small metal oxide particles or any chemical which is not coated silver nanowires.
  • the coated silver nanowires are submitted to at least 2 dispersion-centrifugation cycles in the solvent, sometimes to at least 3 dispersion-centrifugation cycles, rarely to at least 4 dispersion-centrifugation cycles.
  • the solvent may be the polar aprotic solvent suitable for the invention as will be described below.
  • the composition according to the invention comprises generally at least 50 wt. %, often at least 60 wt. %, sometimes at least 70 wt. % and rarely at least 80 wt. % of fluorinated polymer with regard to the total weight of the composition. Besides, the composition comprises generally at most 99.5 wt. %, often at most 99.0 wt. % and sometimes at most 98 wt. % of polymer.
  • the composition according to the invention comprises generally at least 0.5 wt. %, often at least 1 wt. % and sometimes at least 2 wt. % of silver nanowires coated by metal oxide with regard to the total weight of the composition. Besides, the composition comprises generally at most 50 wt. %, often at most 40 wt. %, sometimes at most 30 wt. % and rarely at most 20 wt. % of silver nanowires.
  • composition according to the invention is generally free of any surfactant. This is a desirable situation when the composition is aimed to be used in very demanding applications. For example, it may be the case when the composition is intended to be used for preparing materials comprising silver nanowires coated with at least one metal oxide and fluorinated polymers for some electronic applications.
  • the weight ratio of surfactant with regard to Ag metal is generally of at most 0.01 wt. %, often of at most 0.005 wt. %.
  • the composition comprises at least one surfactant.
  • the weight ratio of surfactant with regard to Ag metal is generally of at least 0.1 wt. %. It is preferably of at least 0.5 wt.% and more preferably of at least 1 wt.%.
  • the weight ratio of surfactant with regard to Ag metal is generally of at most 250 wt.%. It is often of at most 200 wt.% and more possibly of at most 150 wt.%.
  • a surfactant is a substance which lowers the surface tension of the medium in which it is dissolved, and/or the interfacial tension with other phases, and, accordingly, is positively adsorbed at the liquid/ vapor and/or at other interfaces.
  • the surfactant that may be present in the composition according to the invention can be selected from the list consisting of anionic, cationic,
  • amphoteric, non- ionic surfactants and mixtures thereof.
  • Anionic surfactants suitable for the invention are generally chosen from the list consisting of phosphates, sulfonates, sulfates, carboxylates and mixtures thereof.
  • Cationic surfactants suitable for the invention are generally chosen from the list consisting of phosphonium, ammonium and pyridinium salts.
  • Ammonium salts corresponding to the formula (1) are preferred : !-N- 4 X
  • R l s R 2 , R 3 and R4 which may be the same or different represent H or a Ci-C 3 o hydrocarbyl or heterohydrocarbyl group and,
  • X is an halogen atom or an alkyl sulfate group.
  • hydrocarbyl refers to a group only containing carbon and hydrogen atoms.
  • the hydrocarbyl group may be saturated or unsaturated, linear, branched or cyclic. If the hydrocarbyl is cyclic, the cyclic group may be an aromatic or non-aromatic group.
  • heterohydrocarbyl refers to a hydrocarbyl group wherein one or more of the carbon atom(s) is/are replaced by a heteroatom, such as Si, S, N or O. Included within this definition are heteroaromatic rings, i.e. wherein one or more carbon atom within the ring structure of an aromatic ring is replaced by a heteroatom.
  • cetyl trimethyl ammonium bromide is advantageously used.
  • Amphoteric surfactants suitable for the invention are generally chosen from the list consisting of betaines, sulfobetaines and amine oxides.
  • Cocamidopropyl dimethyl betaine and lauramidopropyl betaine, coco hydroxypropyl sulphobetaine and dodecyl hydroxypropyl sulphobetaine, coco N, N - dimethylamine-N-oxide and N, N - dimethyldodecylamine-N-oxide are examples of respectively adequate betaines, sulfobetaines and amine oxides.
  • Non- ionic surfactants suitable for the invention are generally chosen from the list consisting of alkoxylates, pyrrolidinones, glycerides, glycosides and amines.
  • Lauryl alcohol ethoxylate, nonyl phenol ethoxylate, stearyl alcohol ethoxylate and cetostearyl alcohol ethoxylate are examples of appropriate alkoxylates .
  • Suitable amines correspond to the formula NR 5 R 6 R 7 wherein R5, and R 7 , which may be the same or different represent H or a C1-C30 hydrocarbyl or heterohydrocarbyl group; n-dodecylamine is an example of appropriate amine. The inventors have found advantageous to use n-dodecylamine. Good results were obtained using Fentamine® A12 available from Solvay Novecare.
  • suitable non-ionic surfactants are chosen from poly(alkylene oxide)s.
  • Poly(alkylene oxide)s suitable for use in the present invention are polymers essentially all or all the repeating units of which comply with general formula -C n H2 n -0- wherein -C n H2 n - represents a divalent alkylene group with n ranging from 2 to 10. Such poly(alkylene oxide)s may be terminated by a hydroxyl group.
  • the poly(alkylene oxide)s may be either linear or branched.
  • Linear poly(alkylene oxides) are generally preferred.
  • suitable poly(alkylene oxide)s include
  • polyoxyalkylene polyols such as polyoxy ethylene glycol (also known as poly(ethylene glycol) or poly(ethylene oxide), polyoxyethylene triol, polyoxyethylene tetraol, polyoxypropylene glycol (also commonly referred to as poly(propylene glycol) or poly(propylene oxide), polyoxypropylene triol, polyoxypropylene tetraol, polyoxybutylene glycol, , polyoxypentane glycol, polyoxyhexane glycol, polyoxyheptane glycol, and polyoxyoctane glycol.
  • These polymers may be used either individually or in combinations of two or more; for example, it can be cited random copolymers of ethylene oxide and propylene oxide, and poly(ethylene oxide)-poly(propylene oxide) block copolymers.
  • hydroxyl end groups of the poly(alkylene oxide)s may according to a preferred embodiment be partly or fully substituted by alkoxide groups, preferably methoxy or alkoxy.
  • alkoxide groups preferably methoxy or alkoxy.
  • Suitable oxyalkylene-containing compounds suitable in the compositions in accordance with the instant invention are amine-terminated poly(alkylene oxide)s, in particular amine-terminated poly(ethylene oxide)s or amine-terminated poly(propylene oxide)s, including copolymers comprising both mentioned types of oxyalkylene units which are commercially available under the tradename Jeffamine® from Huntsman Chemical Corporation.
  • poly(alkylene oxide)s having a number average or weight average molecular weight of at least 20,000, preferably at least 200,000 and even more preferably at least 1,000,000 are advantageous. In other cases average molecular weights of at most 20,000, preferably at most 10,000 and even more preferably at most 1000 are useful.
  • the molecular weight of the poly(alkylene oxides) suitable may also be optimized. For example, a methoxy-terminated poly(ethylene oxide) having a number average or a weight average molecular weight of at most 2,000 may be used.
  • Copolymers comprising oxy ethylene and oxypropylene units in random or block distribution may also be suitable and respective products are commercially available under the tradename Pluronics® from BASF and Synperonics® from CRODA.
  • composition according to the invention is generally free of any solvent. Often it is substantially free of any solvent.
  • a polar aprotic solvent can be present generally in an amount not exceeding 0.5 wt. %, often not exceeding 0.2 wt. % sometimes not exceeding 0.1 wt. % based on the total weight of the composition.
  • the fluorinated polymer is dissolved in at least one polar aprotic solvent.
  • the composition contains generally at least 50 wt. %, preferably at least 60 wt. %, more preferably at least 70 wt. % of the solvent, based on the total weight of the composition.
  • the composition contains generally at most 95 wt. %, preferably at most 90 wt. % of solvent, based on the total weight of the composition.
  • the composition When the fluorinated polymer is dissolved in polar aprotic solvent, the composition contains at least 5 wt. % of the fluorinated polymer, often at least 10 wt. %. Besides, the composition contains generally at most 50 wt. % of the fluorinated polymer, often at most 40 wt. %, possibly at most 30 wt. %, based on the total weight of the composition.
  • composition comprising from 10 to 30 wt. % of the fluorinated polymer and from 90 to 70 wt. % of the solvent, wherein the aforementioned wt. % are based on the total weight of the composition.
  • the Ag content in such a composition is generally of at least 50 ppm. It is often of at least 100 ppm.
  • the Ag content in the composition is generally of at most 200000 ppm. It is often of at most 50000 ppm and sometimes of at most 10000 ppm.
  • the molar ratio between Ag and the surfactant is generally of at least 0.05 and often of at least 0.1.
  • the molar ratio between Ag and the surfactant is generally of at most 1000. It is often of at most 500 and possibly of at most 250.
  • the weight ratio of surfactant with regard to Ag metal is generally of at least 0.1 wt. %. It is often of at least 0.5 wt.% and possibly of at least 1 wt.%.
  • the weight ratio of surfactant with regard to Ag metal is generally of at most 250 wt.%. It is often of at most 200 wt.% and possibly of at most 150 wt.%.
  • the solvent suitable for the composition according to the invention is chosen among polar aprotic solvents.
  • a polar aprotic solvent is a solvent with high dielectric constant and a sizable permanent dipole moment that cannot donate suitably labile hydrogen atoms to form strong hydrogen bonds.
  • Polar aprotic solvents suitable for the process according to the invention are solvents having a dielectric constant measured at 20 °C generally over 5.
  • the dielectric constant of the polar aprotic solvent is preferably more than 10, more preferably more than 12 and even more preferably more than 15.
  • the dielectric constant of solvents can be determined using for example BI-870 Dielectric Constant Meter available from Brookhaven Instruments Corporation, following the recommendations of the provider.
  • Suitable polar aprotic solvents are solvents having a dipole moment generally over 0.5 Debye.
  • the dipole moment of the polar aprotic solvent is preferably more than 1.0 Debye, more preferably more than 1.5 Debye and even more preferably more than 2.0 Debye.
  • Suitable polar aprotic solvents are solvents having a normal boiling point generally below 250°C, preferably below 200°C, more preferably below 150°C and even more preferably below 100°C.
  • Suitable polar aprotic solvents have a boiling point generally above 40 °C and preferably above 50°C.
  • Normal boiling point is measured at atmospheric pressure by any method well known by the skilled person.
  • the solvent suitable for the process according to the invention is generally chosen in the list consisting of ketones, ethers, esters, amides, nitriles, sulfoxides and mixtures thereof.
  • the solvent suitable for the process according to the invention is generally chosen in the list consisting of ketones, ethers, esters, amides, nitriles, sulfoxides, carbonates and mixtures thereof.
  • dimethylacetamide and mixtures thereof may be used; among esters, ethylacetate, cyclohexyl acetate may be used; among ethers, 2- methyltetrahydrofuran, tetrahydrofuran and mixture thereof may be used; among nitriles, acetonitrile may be used; among sulfoxides, dimethylsulfoxide may be used and among carbonates dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, ethylmethyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate may be used.
  • mixture of ethers with amides such as a mixture of 2-methyltetrahydrofurane with dimethylformamide may be used.
  • the solvent suitable for the process according to the invention can be chosen in the list consisting of ketones, ethers, esters, amides, nitriles, sulfoxides carbonates, of solvents which are mixtures consisting essentially of at least 80% by weight of H 3 CO(0)C-CH(CH 3 )-CH 2 -CH 2 - C(0)OCH 3 and H 3 CO(0)C-CH(C 2 H 5 )-CH 2 -C(0) OCH 3 such as
  • RHODIASOLV ® IRIS provided by Solvay, of solvents which are mixtures consisting essentially of at least 80% by weight of H 3 CO(0)C-CH(CH 3 )-CH 2 - CH 2 -C(0)N(CH 3 ) 2 and H 3 CO(0)C-CH(C 2 H 5 )-CH 2 -C(0) N(CH 3 ) 2
  • RHODIASOLV ® POLARCLEAN provided by Solvay
  • solvents which are mixtures consisting essentially of at least 70%> by weight of H 3 CO(0)C-(CH 2 ) 3 - C(0)OCH 3 and H 3 CO(0)C-(CH 2 ) 2 -C(0)OCH 3 such as RHODIASOLV ® RPDE provided by Solvay, of solvents consisting essentially of (H 3 C) 2 HC-H 2 C-0(0)C- (CH 2 )4-C(0)0-CH 2 -CH(CH 3 )2, (H 3 C)2HC-H 2 CO(0)C-(CH 2 ) 3
  • the solvent is selected from ketones and mixtures thereof.
  • Acetone, methylethyl ketone, diethyl ketone, cyclopentanone, cyclohexanone and mixtures thereof are advantageously used and methylethyl ketone may be preferred.
  • composition according to the invention may additionally comprise at least one other ingredient; for example, it may comprise a stabilizer, a plasticizer or a processing aid.
  • a stabilizer for example, it may comprise a stabilizer, a plasticizer or a processing aid.
  • Good results can be obtained with compositions composed essentially of, or even composed of the silver nanowires coated with at least one metal oxide, optionally the surfactant, the fluorinated polymer and the polar aprotic solvent.
  • the process comprises the steps of: - dispersing silver nano wires coated with at least one metal oxide in a polar aprotic solvent optionally in the presence of at least one surfactant so as to obtain a suspension (a),
  • composition (d) substantially free of solvent i.e. generally comprising an amount not exceeding 0.5 wt. % of solvent based on the total weight of the composition (d), or even free of any solvent.
  • composition (g) substantially free of solvent i.e. generally comprising an amount not exceeding 0.5 wt. % of solvent based on the total weight of the composition (g), or even free of any solvent.
  • compositions (f) and (g) have the same features as respectively
  • the process comprises the steps of:
  • composition (j) substantially free of solvent i.e. generally comprising an amount not exceeding 0.5 wt. % of solvent based on the total weight of the composition (j), or even free of any solvent.
  • compositions (i) and (j) have the same features as respectively
  • Dispersing the silver nanowires coated with at least one metal oxide in a polar aprotic solvent so as to obtain the suspension (a) or (e) is generally conducted by sonication. However, any other mean of providing energy to the mixture may be used. Dispersing can be conducted, for example and not in a limitative way, by using vessels equipped with agitator and optionally baffles, static mixers or high shear dispersers.
  • Solutions (b) and (h) may be obtained by dissolving the fluorinated polymer in the polar aprotic solvent under stirring possibly accompanied by heating.
  • mixing the suspension (a) with the solution (b) can be performed by mechanical stirring of the mixture in a vessel.
  • this mechanical stirring is accompanied by further sonication.
  • the sonication may advantageously allow the homogeneous dispersion of the silver nanowires in the composition.
  • compositions (c), (f) and (i) have all the features of the composition according to the invention wherein the fluorinated polymer is dissolved in at least one polar aprotic solvent as previously described.
  • Removal of the solvent can be obtained for example by spray drying of the compositions (c), (f) or (i) or by heating the composition (c), (f) or (i) in an oven under vacuum. However any other process well known by the skilled person can be used.
  • spray drying the composition is recovered as a powder.
  • All the steps of the process for preparing the composition are generally conducted under inert atmosphere which may be nitrogen or argon atmosphere.
  • compositions (d), (g) and (j) have all the features of the composition according to the invention which is generally free of any solvent or often is substantially free of any solvent.
  • composition (d), (g) or (j) comprises a polar aprotic solvent generally in an amount not exceeding 0.5 wt. %, often not exceeding 0.2 wt. % and sometimes not exceeding 0.1 wt. % based on the total weight of the composition.
  • composition substantially free or even free of any solvent as previously described in an extrusion and/or in a molding process.
  • the composition obtained as a powder after removal of the solvent by spray drying may be used in compression or injection molding. It may also be used in extrusion to prepare granules.
  • Still another object of the invention is to disclose a process for preparing a film comprising the steps of:
  • composition according to the invention wherein the fluorinated polymer is dissolved in at least one polar aprotic solvent as previously described on a substrate, so as to form a swollen film,
  • Removal of the solvent can be obtained for example by heating the swollen film in an oven but any other process well known by the skilled person can be used.
  • the substrate can notably be a plate of a chemically inert material and casting can be performed using for example a doctor blade device.
  • the chemically inert material is glass.
  • the film is recovered by dipping the substrate into a water bath.
  • the film After removal of the solvent, the film is generally free of any solvent; often it is substantially free of any solvent. In the latter case it comprises a solvent in an amount generally not exceeding 0.5 wt. %, often not exceeding 0.2 wt. % and sometimes not exceeding 0.1 wt. % based on the total weight of the film.
  • Another object of the invention is to disclose a film obtainable by the process as above described, said film having the same composition as the composition obtained by the process according to the invention after solvent removal as previously described.
  • the film may additionally comprise at least one other ingredient; for example, it may comprise a stabilizing agent, a plasticizer or a processing aid.
  • the film obtained by the process according to the invention has generally an average thickness not exceeding 200 ⁇ , preferably not exceeding 100 ⁇ , more preferably not exceeding 50 ⁇ .
  • the average thickness of the film according to the invention is at least 5 ⁇ , preferably at least 10 ⁇ , more preferably at least 15 ⁇ . In a most preferred embodiment, the average thickness of the film ranges froml5 ⁇ to 50 ⁇ .
  • the thickness may be measured using a digital micrometer onto the film recovered from the process described above.
  • the value can be the average value of at least ten different measurements made along the film and distanced of at least 1 cm.
  • the silver nanowires dispersion in the film can be evaluated by scanning electron microscopy.
  • the content of silver in the film can be determined by inductively coupled plasma optical emission spectrometry (ICP-OES).
  • ICP-OES inductively coupled plasma optical emission spectrometry
  • the intensity of the emission measured for a sample diluted in nitric acid 5% aqueous solution at the silver specific wavelength is compared to a calibration curve in a similar range of concentration of silver standards obtained in similar analytical conditions.
  • Dielectric measurements can be performed onto films beforehand metallized using a sputtering coater such as Q150R S available from Quorum Technologies.
  • a sputtering coater such as Q150R S available from Quorum Technologies.
  • Modulab XM-MTS equipment from Solartron Analytical may be used following the recommendation of the provider.
  • the dielectric permittivity and dielectric loss are plotted as function of frequency and the dissipation factor tan ⁇ is calculated:
  • ⁇ " is the dielectric loss and ⁇ ' the dielectric permittivity.
  • Breakdown voltage is the minimum voltage that causes the film to become electrically conductive. It can be measured onto films beforehand metallized by methods well known to those skilled in the art.
  • Another object of the invention is a film having the same composition as the composition according to the invention and having all the features of the film obtained by the process according to the invention.
  • the present invention relates to a device comprising such a film.
  • said device may be a sensor (in particular a haptic sensor), an actuator (in particular a haptic actuator), an energy harvesting or an energy storage device.
  • the device can be used in haptic applications.
  • the dielectric properties of the film according to the invention have a direct influence onto the behavior of the device.
  • an actuator comprising a film having a dielectric permittivity ⁇ ' and a low tan ⁇ will give a larger deformation than an actuator having the same ⁇ ' but a higher tan ⁇ at a given voltage V.
  • a sensor comprising a film having a dielectric permittivity ⁇ ' and a low tan ⁇ will give a better electrical response to pressure than a sensor having the same ⁇ ' but a higher tan ⁇ .
  • Silver nanowires were synthesized using the classical polyol route in propylene glycol using PVP as directing agent. At the end of the synthesis the reaction was quenched with cold water. The resulting slurry was composed of silver nanowires and silver nanoparticles in a propylene glycol/water mixture.
  • the slurry obtained (1750g) was filtered using a nylon filter made of 5 ⁇ pores.
  • the resulting cake was then dispersed in 270g of water by sonication in a water bath using a Bransonic® 221 sonifier during 5 min. at 48 kHz and 50W.
  • the obtained concentrated suspension of silver nanowire was titrated by potentiometry using a solution of potassium iodine at 0.05M. The measurement was carried out after digestion of a sample in nitric acid 5% aqueous solution and further dilution in water. The content of the silver was 7585 ppm.
  • a volume of the suspension in water corresponding to lg of solid silver nanowires (AgNW) was transferred from water to methylethyl ketone (MEK) by 3 cycles of centrifugation (4500 rpm during 30min) /dispersion with a final dispersion of the AgNW into 12g of MEK.
  • MEK methylethyl ketone
  • lg of silver nanowires obtained by filtration were dispersed under 100 rpm stirring in 731.5 g of an ethanol/water mixture (5 / 1 vol. / vol.) and the suspension was heated at 40°C in an oil bath before 20 ml of a solution of ammonia 28 wt. % in water was added. Then 708 of tetraethylortho silicate (TEOS) was added dropwise to the solution under stirring and the reaction conducted during 90 min. The suspension was centrifugated at 4500 rpm during 30 min to remove the solvent, ammonia and unreacted TEOS and redispersed in ethanol before being centrifugated again for washing ammonia and unreacted TEOS.
  • TEOS tetraethylortho silicate
  • Silver nanowires coated with silica were then transferred in methylethyl ketone (MEK) by 2 cycles of centrifugation/dispersion with a final dispersion of the AgNW@Si0 2 into 12g of MEK.
  • MEK methylethyl ketone
  • Flurinated polymer used to prepare the films was P(VDF-TrFE-CTFE) terpolymer Solvene ® T provided by Solvay Specialty Polymers.
  • the dispersion comprising lg of AgNW@Si0 2 and 12 g of MEK was introduced in a polypropylene centrifugating tube. A vortex stirring was applied to the tube using Vortex 4 basic equipment provided by Ika to ensure dispersion of AgNW@Si0 2 and the obtained dispersion was poured in a Schott duran bottle. The centrifuging tube was rinsed with a little MEK to recover the totality of AgNW@Si0 2 .
  • Ultrasonication was then performed using UP200ST ultrasonication system provided by Hieschler equipped with Sonotrode S2d7 operating at 40 watt for 15 min. under nitrogen without exceeding -4°C.
  • the dispersion was stirred with a magnetic bar and 2.07 grams of terpolymer Solvene ® T were added.
  • the dispersion was then heated under stirring at 75°C in a bath of water so that the polymer dissolved and the MEK evaporated until the solid content reached 24,7 wt. % of MEK.
  • a glass plate was cleaned with a sponge using tap water and soap, then rinced in ethanol and wiped with a cloth (special white room Essuyeur specW7 provided by VWR).
  • the glass plate was then positioned on the 4340 automatic table from
  • the adjustable applicator was also cleaned with acetone, as well as the 700 ⁇ knife setting.
  • the applicator was positioned on the glass plate, against the mobile cart the Elcometer table.
  • the dispersion to cast was then placed on the plate close to the applicator and the mobile cart of the Elcometer table was put in motion at speed 2 at room temperature.
  • the intensity measured on the Silver specific wavelength (eg. 328.068, 338.289 nm and 241.318nm) was compared to a calibration curve obtained in similar analytical conditions in order to determine the amount in the diluted solution.
  • the amount in the solution was obtained by calculation using the dilution factor.
  • the calibration curve was prepared using silver standards in the range of 0 to 15 mg/L comprising Sc as internal standard and the same amount of H2SO4 as the samples.
  • ICP-OES measurements carried out onto film 1 comprising AgNW coated with S1O 2 gave an amount of 18.4 wt. % of Ag compared to the total weight of the film while for film 2 comprising non coated AgNW an amount of 25.0 wt. % of Ag was obtained. These amounts were in same order of magnitude as the theoretical amounts which were 33.3 wt. % and revealed a good dispersion of the nanowires into the terpolymer matrix.
  • the tests were carried out at room temperature onto dried films.
  • One side of the film was metalized with gold using a sputtering coater such as Q150R S available from Quorum Technologies.
  • the other side was partially metalized using the same apparatus on a central disk of 20 mm diameter in order to preserve a non-metalized ring which ensured the insulation between the 2 sides of the sample.
  • the metalization was performed four times on each side, at 30mA for 120 seconds.
  • the samples were placed between 2 stainless steel electrodes of 20 mm diameter connected to the Modulab XM-MTS equipment from Solartron Analytical.
  • the configuration corresponded to high impedance setup with reference capacitor.
  • the applied voltage was 2.5 volts in amplitudes with an offset to 0 Volt.
  • the frequency sweep was done from 1 MHz to 0.1 Hz through 10 measures by decades.
  • Table 1 The results of dielectric measurements are compiled in table 1.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
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  • Compositions Of Macromolecular Compounds (AREA)

Abstract

La présente invention concerne une composition comprenant au moins un polymère fluoré et des nanofils d'argent revêtus d'au moins un oxyde métallique et un procédé de préparation de ladite composition. Elle concerne également des films comprenant ladite composition et des procédés de préparation de ces films.
PCT/EP2018/077808 2017-10-12 2018-10-11 Composition comprenant des nanofils d'argent et au moins un polymère fluoré WO2019073012A1 (fr)

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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
WO2021084074A1 (fr) 2019-10-30 2021-05-06 Solvay Sa Compositions et films comprenant un polymère et des particules de tis2, leur préparation et leurs utilisations

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WO2014028027A1 (fr) 2012-08-17 2014-02-20 Empire Technology Development Llc Nanocomposites de plastique et leurs procédés de fabrication
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WO2014028027A1 (fr) 2012-08-17 2014-02-20 Empire Technology Development Llc Nanocomposites de plastique et leurs procédés de fabrication
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
WO2021084074A1 (fr) 2019-10-30 2021-05-06 Solvay Sa Compositions et films comprenant un polymère et des particules de tis2, leur préparation et leurs utilisations

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