Polymer compound for a conductive polymer and method for producing same

Abstract

A polymer compound for a conductive polymer including one or more repeating units a shown by the following general formula (1), and having a weight-average molecular weight in the range of 1,000 to 500,000, ##STR00001##
wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents any of a single bond, an ester group, and a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms and optionally containing either or both of an ether group and an ester group; R.sup.3 represents a linear or branched alkyl group having 1 to 4 carbon atoms with one or more hydrogen atoms in R.sup.3 being substituted by a fluorine atom(s); Z represents any of a single bond, a phenylene group, a naphthylene group, an ether group, and an ester group; and a is a number satisfying 0<a1.0.

Claims

1. A polymer compound for a conductive polymer comprising one or more repeating units a shown by the following general formula (1), and having a weight-average molecular weight in the range of 1,000 to 500,000, ##STR00032## wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents any of a single bond, an ester group, an ether group, and a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms; R.sup.3 represents a linear or branched alkyl group having 1 to 4 carbon atoms with one or more hydrogen atoms in R.sup.3 being substituted by a fluorine atom(s); Z represents any of a single bond, a phenylene group, a naphthylene group, an ether group, and an ester group; and a is a number satisfying 0<a1.0, wherein the one or more repeating units a shown by the general formula (1) contain a repeating unit a1 shown by the following general formula (3), ##STR00033## wherein R.sup.1 and R.sup.3 have the same meanings as defined above, and a1 is a number satisfying 0<a11.0.

2. The polymer compound for a conductive polymer according to claim 1, further comprising a repeating unit b shown by the following general formula (2), ##STR00034## wherein b is a number satisfying 0<b<1.0.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) As mentioned above, it has been desired to develop a polymer compound for a conductive polymer which is soluble in an organic solvent, and suitably used for a fuel cell or a dopant for a conductive material.

(2) For the purpose of changing a water-soluble conductive polymer containing water, which causes the deterioration of an organic EL device, into an organic solvent-soluble polymer containing an extremely little water to prevent the deterioration of a device, the present inventors have tried to develop a polymer for a dopant having high solubility in an organic solvent from polystyrene sulfonic acid, which is a dopant soluble in water but difficulty soluble in an organic solvent. Since it is effective for increasing solubility in an organic solvent to introduce a long-chain alkyl group or a fluorine atom, they have investigated to introduce a fluorine atom, but found that the introduction of a long-chain alkyl group or an excess fluorine atom is not favorable since they cause lowering of the conductivity. Accordingly, the next aim has been set to construct a strongly acidic unit with introducing a smaller amount of fluorine atoms. Although the foregoing bisfluoroalkylsulfonylimide has high acidity, having fluoroalkyl groups at the both sides, it shows low conductivity when applied as a dopant polymer. Therefore, the present inventors have found that an introduction of a sulfonate ester group into one side of bisfluoroalkylsulfonylimide can give a sulfonimide group having sufficiently high acidity with small amount of fluorine atoms due to the high electron withdrawing property of the sulfonate ester group, and a polymer compound composed of the repeating unit having this group can achieve the foregoing purpose, thereby bringing the invention to completion.

(3) That is, the present invention is a polymer compound for a conductive polymer comprising one or more repeating units a shown by the following general formula (1), and having a weight-average molecular weight in the range of 1,000 to 500,000,

(4) ##STR00008##
wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents any of a single bond, an ester group, and a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms and optionally containing either or both of an ether group and an ester group; R.sup.3 represents a linear or branched alkyl group having 1 to 4 carbon atoms with one or more hydrogen atoms in R.sup.3 being substituted by a fluorine atom(s); Z represents any of a single bond, a phenylene group, a naphthylene group, an ether group, and an ester group; and a is a number satisfying 0<a1.0.

(5) Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

(6) Herein, conductive means electrically conductive.

(7) The inventive polymer compound for a conductive polymer is a polymer which contains one or more repeating units a shown by the following general formula (1). The inventive polymer compound for a conductive polymer can have particularly high transparency by containing the repeating units a shown by the following formula (1),

(8) ##STR00009##
wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents any of a single bond, an ester group, and a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms and optionally containing either or both of an ether group and an ester group; R.sup.3 represents a linear or branched alkyl group having 1 to 4 carbon atoms with one or more hydrogen atoms in R.sup.3 being substituted by a fluorine atom(s); Z represents any of a single bond, a phenylene group, a naphthylene group, an ether group, and an ester group; and a is a number satisfying 0<a1.0.

(9) In the general formula (1), R.sup.1 is a hydrogen atom or a methyl group.

(10) R.sup.2 is any of a single bond, an ester group, and a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms and optionally containing either or both of an ether group and an ester group. As the hydrocarbon group, for example, alkylene groups, arylene groups (such as a phenylene group and a naphthylene group), alkenylene groups are mentioned.

(11) Z is any of a single bond, a phenylene group, a naphthylene group, an ether group, and an ester group.

(12) a is a number satisfying 0<a1.0.

(13) It is preferred that the repeating unit a shown by the general formula (1) contain a repeating unit a1 shown by the following general formula (3),

(14) ##STR00010##
wherein R.sup.1 and R.sup.3 have the same meanings as defined above, and a1 is a number satisfying 0<a1.0.

(15) When such a repeating unit is contained, the polymer compound is more suitable for a fuel cell or a dopant for a conductive material.

(16) It is preferred that the inventive polymer compound for a conductive polymer further comprise a repeating unit b shown by the following general formula (2). When the repeating unit a is copolymerized with the polystyrene sulfonic acid of the repeating unit b, the polymer compound can be used as a dopant polymer with high conductivity,

(17) ##STR00011##
wherein b is a number satisfying 0<b<1.0.

(18) As described later, the inventive polymer compound for a conductive polymer can contain a repeating unit c, other than the repeating unit a and the repeating unit b.

(19) The inventive polymer compound for a conductive polymer has a weight-average molecular weight in the range of 1,000 to 500,000, preferably 2,000 to 200,000. If the weight-average molecular weight is less than 1,000, the polymer compound is inferior in heat resistance. On the other hand, if the weight-average molecular weight exceeds 500,000, its viscosity is increased, workability is worsened, and solubility in an organic solvent and water is lowered.

(20) The weight average molecular weight (Mw) is a measured value in terms of polystyrene by gel permeation chromatography (GPO) using water, dimethylformamide (DMF), or tetrahydrofuran (THF) as a solvent.

(21) The foregoing polymer compound for a conductive polymer of the present invention can be a polymer compound for a conductive polymer having a specific superacidic sulfonimide group which is soluble in an organic solvent, and suitably used for a fuel cell or a dopant for a conductive material.

(22) The present invention also provides a method for producing such an inventive polymer compound for a conductive polymer.

(23) That is, the inventive producing method is a method for producing a polymer compound for a conductive polymer containing a repeating unit a shown by the following general formula (1), comprising the steps of:

(24) subjecting to polymerization reaction using a monomer having a structure of a salt composed of a sulfonimide group and lithium, sodium, potassium, or a nitrogen compound; and after the polymerization reaction,

(25) converting the structure of the salt composed of a sulfonimide group and lithium, sodium, potassium, or a nitrogen compound to a sulfonimide group by ion exchange,

(26) ##STR00012##
wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents any of a single bond, an ester group, and a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms and optionally containing either or both of an ether group and an ester group; R.sup.3 represents a linear or branched alkyl group having 1 to 4 carbon atoms with one or more hydrogen atoms in R.sup.3 being substituted by a fluorine atom(s); Z represents any of a single bond, a phenylene group, a naphthylene group, an ether group, and an ester group; and a is a number satisfying 0<a1.0.

(27) At this time, it is preferred that the polymerization reaction using a monomer having a structure of a salt composed of a sulfonimide group and lithium, sodium, potassium, or a nitrogen compound give a polymer which contains a repeating unit shown by the following general formula (4),

(28) ##STR00013##
wherein R.sup.1, R.sup.2, R.sup.3, Z, and a have the same meanings as defined above, and X represents lithium, sodium, potassium, or a nitrogen compound shown by the following general formula (5),

(29) ##STR00014##
wherein R.sup.101d, R.sup.101e, R.sup.101f, and R.sup.101g each represent a hydrogen atom, or a linear, branched, or cyclic alkyl group, alkenyl group, oxoalkyl group, or oxoalkenyl group each having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group or an aryloxoalkyl group each having 7 to 12 carbon atoms where a part or all of hydrogen atoms in these groups may be substituted by an alkoxy group(s); R.sup.101d and R.sup.101e, or R.sup.101d, R.sup.101e, and R.sup.101f may form a ring together, and when the ring is formed, R.sup.101d and R.sup.101e, or R.sup.101d, R.sup.101e, and R.sup.101f represent an alkylene group having 3 to 10 carbon atoms or a heteroaromatic ring having therein the nitrogen atom in the formula.

(30) Such a repeating unit can be easily converted to the repeating unit a shown by the general formula (1) by ion exchange, thereby being preferable.

(31) The followings are illustrative examples of the monomer which can be used for the inventive producing method, each having a structure of a salt composed of a sulfonimide group and lithium, sodium, potassium, or a nitrogen compound to give a repeating unit a,

(32) ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019##
wherein R.sup.1 has the same meaning as defined above, and X represents lithium, sodium, potassium, or a nitrogen compound.

(33) As described above, it is preferred that the repeating unit a shown by the general formula (1) contain a repeating unit a1 shown by the foregoing general formula (3). That is, monomers to give the repeating unit a1 are particularly preferable among the exemplified monomers described above.

(34) As also described above, the inventive polymer compound for a conductive polymer preferably has a repeating unit b shown by the general formula (2). As the monomer to give the repeating unit b, the following can be specifically exemplified.

(35) ##STR00020##
wherein, X.sub.2 represents a hydrogen atom, lithium, sodium, potassium, a nitrogen compound, or a sulfonium compound.

(36) Illustrative examples of which the X.sub.2 is a nitrogen compound include a compound shown by the following general formula (5),

(37) ##STR00021##
wherein R.sup.101d, R.sup.101e, R.sup.101f, and R.sup.101g each represent a hydrogen atom, or a linear, branched, or cyclic alkyl group, alkenyl group, oxoalkyl group, or oxoalkenyl group each having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group or an aryloxoalkyl group each having 7 to 12 carbon atoms where a part or all of hydrogen atoms in these groups may be substituted by an alkoxy group(s); R.sup.101d and R.sup.101e, or R.sup.101d, R.sup.101e, and R.sup.101f may form a ring together, and when the ring is formed, R.sup.101d and R.sup.101e, or R.sup.101d, R.sup.101e, and R.sup.101f represent an alkylene group having 3 to 10 carbon atoms or a heteroaromatic ring having therein the nitrogen atom in the formula.

(38) As described above, the inventive polymer compound for a conductive polymer can contain a repeating unit c, other than the repeating unit a and the repeating unit b. Illustrative examples of this repeating unit c include a styrene base, a vinylnaphthalene base, a vinylsilane base, acenaphthylene, indene, vinylcarbazole.

(39) Illustrative examples of the monomer to give the repeating unit c include the following.

(40) ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028##

(41) As a method for synthesizing the polymer compound for a conductive polymer of the present invention, for example, a method in which desired monomers among the above-described monomers are subjected to heat polymerization by adding a radical polymerization initiator in a solvent to obtain a polymer compound, which is a copolymer, may be mentioned.

(42) Illustrative examples of the solvent to be used for the polymerization include water, methanol, ethanol, n-propanol, isopropyl alcohol, methoxyethanol, ethoxyethanol, n-butanol, ethylene glycol, propylene glycol, glycerin, diethylene glycol, dimethylsulfoamide, dimethylacetamide, acetone, dimethyl sulfoxide, N-methylpyrrolidone, toluene, benzene, tetrahydrofuran, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone, and -butyrolactone.

(43) Illustrative examples of the radical polymerization initiator include di-tert-butyl peroxide, dicumyl peroxide, tert-butylcumyl peroxide, benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl peroxyisobutyrate, potassium persulfate, ammonium persulfate, hydrogen peroxide, 2,2-azobisisobutyronitrile (AIBN), 2,2-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), lauroyl peroxide, 2,2-azobis(2-amidinopropane) dihydrochloride, or an alkali metal salt or an ammonium salt of 4,4-azobis(4-cyanovaleric acid).

(44) The reaction temperature is preferably in the range of 50 to 80 C., and the reaction time is preferably in the range of 2 to 100 hours, more preferably 5 to 20 hours.

(45) In the polymer compound for a conductive polymer of the present invention, the monomer that gives the repeating unit a shown by the general formula (1) may be used alone or in combination with two or more kinds, and it is preferred to combine methacryl type and styrene type monomers for the sake of enhancing polymerizability.

(46) In addition, two or more kinds of monomers constituting the repeating unit a may be random-copolymerized, or may be each block-copolymerized. When a block-copolymerized polymer (block copolymer) is used as a conductive film, it can be expected to obtain a merit that the conductivity is improved by aggregating the repeating unit portions composed of the two or more kinds of the repeating units a with each other to form a sea-island structure.

(47) Moreover, the monomers that give the repeating units a to c may be random-copolymerized, or may be each block-copolymerized. In this case, it can also be expected to obtain a merit that the conductivity is improved due to the block copolymer as explained for the repeating unit a above.

(48) When a random copolymerization is carried out by a radical polymerization, the method is generally used in which monomers and a radical polymerization initiator to be used for the copolymerization are mixed and polymerized by heating. In the case that the polymerization is started with a first monomer in the presence of a radical polymerization initiator, and then adding a second monomer thereto later, the resulting polymer has a structure that the first monomer is polymerized at one side of the polymer molecule, and the second monomer is polymerized at the other side. In this case, however, the repeating units of the first and second monomers are mixedly present at the middle portion, thus it has a different structure from the block copolymer. For forming the block copolymer by radical polymerization, living radical polymerization is preferably used.

(49) In a living radical polymerization method called RAFT polymerization (Reversible Addition Fragmentation chain Transfer polymerization), radicals at the polymer terminal are always living, so that it is possible to form a block copolymer composed of first and second repeating units by starting the polymerization with a first monomer, and then adding a second monomer at the time when the first monomer has been consumed. In addition, it is also possible to form a triblock copolymer by starting the polymerization with a first monomer, then adding a second monomer at the time when the first monomer has been consumed, and then adding a third monomer thereto.

(50) When the RAFT polymerization is carried out, there is a characteristic that a narrowly distributed polymer having a narrow molecular weight distribution (degree of distribution) is obtained. In particular, when the RAFT polymerization is carried out by adding monomers at once, a polymer having a narrower molecular weight distribution can be obtained.

(51) The polymer compound for a conductive polymer of the present invention preferably has a narrow distribution, and the molecular weight distribution (Mw/Mn) thereof is preferably in the range of 1.0 to 2.0, particularly preferably 1.0 to 1.5. The narrow distribution allows to prevent unevenness of the conductivity of the conductive polymer synthesized by using the polymer compound.

(52) To carry out the RAFT polymerization, a chain transfer agent is necessary, and illustrative examples thereof include 2-cyano-2-propylbenzothioate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid, cyanomethyldodecylthiocarbonate, cyanomethylmethyl-(phenyl) carbamothioate, bis(thiobenzoyl)disulfide, and bis(dodecylsulfanylthiocarbonyl)disulfide. Among these, 2-cyano-2-propylbenzothioate is particularly preferred.

(53) The proportion of the repeating units a to c is 0<a1.0, 0b<1.0, and 0c<1.0, preferably 0.1a0.9, 0.1b0.9, and 0c0.8, more preferably 0.2a0.8, 0.2b0.8, and 0c0.5.

(54) Also, it is preferred that a+b+c=1.

(55) In the method for producing the polymer compound for a conductive polymer of the present invention, after polymerizing monomers as mentioned above, the structure of the salt composed of a sulfonimide group and lithium, sodium, potassium, or a nitrogen compound is converted into a sulfonimide group by ion-exchange.

(56) At this time, ion-exchange may be carried out by using, for example, an ion exchange resin.

(57) The polymer compound for a conductive polymer containing the repeating unit a shown by the general formula (1) can be easily produced by the method as mentioned above.

(58) As mentioned above, the polymer compound for a conductive polymer of the present invention can be a polymer compound for a conductive polymer having a specific superacidic sulfonimide group which is soluble in an organic solvent, and suitably used for a fuel cell or a dopant for a conductive material.

(59) When this polymer compound for a conductive polymer is used for a fuel cell, a material for a fuel cell having high dielectric constant can be obtained. Also, when this polymer compound is used as a dopant for a conjugated double bond polymer, a conductive film having high transparency, high conductivity, and high durability can be formed. The inventive polymer compound for a conductive polymer has a specific superacidic sulfonimide group, and accordingly the polymer compound exhibits high performance as a dopant due to the strong ionic bond and high stability as an ion. Therefore, this shows high conductivity and stability when used as a conductive material. Moreover, it is excellent in solubility in an organic solvent, so that deterioration of an organic EL device can be prevented by using it as a conductive film for an organic EL lighting.

(60) Further, the producing method of the present invention facilitates producing such a polymer compound for a conductive polymer of the present invention.

EXAMPLES

(61) In the following, the present invention is specifically explained by referring to Examples, but the present invention is not limited thereto.

(62) In the following, a monomer used in syntheses of Examples are shown.

(63) ##STR00029##
Monomer 1: benzyltrimethylammonium methacryloyloxyethyl-N-[(trifluoromethyl)sulfonyl]sulfamate

Example 1

(64) Under nitrogen atmosphere, to 37.5 g of methanol stirred at 64 C. was added dropwise a solution in which 49.1 g of Monomer 1 and 5.13 g of dimethyl 2,2-azobis(isobutyrate) had been dissolved in 112.5 g of methanol, over 4 hours. The mixture was further stirred at 64 C. for 4 hours. After cooling to room temperature, the mixture was added dropwise to 1,000 g of ethyl acetate under vigorous stirring. The resulting solid was collected by filtration, and dried under vacuum at 50 C. for 15 hours to obtain 26.2 g of a white polymer.

(65) The obtained white polymer was dissolved in 912 g of pure water, and the benzyltrimethylammonium salt was converted into a sulfonimide group by using an ion exchange resin. When the obtained polymer was measured by .sup.19F-NMR, .sup.1H-NMR, and GPC, the following analytical results could be obtained.

(66) Weight-average molecular weight (Mw)=46,000

(67) Molecular weight distribution (Mw/Mn)=1.59

(68) This polymer compound was named Polymer 1.

(69) ##STR00030##

Example 2

(70) Under nitrogen atmosphere, to 37.5 g of methanol stirred at 64 C. was added dropwise a solution in which 24.6 g of Monomer 1, 9.5 g of lithium styrenesulfonate, and 5.13 g of dimethyl 2,2-azobis(isobutyrate) had been dissolved in 112.5 g of methanol, over 4 hours. The mixture was further stirred at 64 C. for 4 hours. After cooling to room temperature, the mixture was added dropwise to 1,000 g of ethyl acetate under vigorous stirring. The resulting solid was collected by filtration, and dried under vacuum at 50 C. for 15 hours to obtain 28.3 g of a white polymer.

(71) The obtained white polymer was dissolved in 912 g of pure water, and the benzyltrimethylammonium salt and the lithium salt were converted into a sulfonimide group and a sulfa group respectively by using an ion exchange resin. When the obtained polymer was measured by .sup.19F-NMR, .sup.1H-NMR, and GPC, the following analytical results could be obtained.

(72) Copolymer Composition Ratio (Molar Ratio)

(73) Monomer 1: styrenesulfonic acid=1:1

(74) Weight-average molecular weight (Mw)=41,000

(75) Molecular weight distribution (Mw/Mn)=1.63

(76) This polymer compound was named Polymer 2.

(77) ##STR00031##

(78) Polymers 1 and 2 synthesized as mentioned above were each soluble in water, methanol, ethanol, isopropyl alcohol, propylene glycol monomethyl ether, tetrahydrofuran, and dimethylformamide.

(79) Thus, the producing method of the present invention facilitates producing the polymer compound for a conductive polymer of the present invention, which has a specific superacidic sulfonimide group, and is soluble in an organic solvent.

(80) It should be noted that the present invention is not limited to the foregoing embodiment. The embodiment is just an exemplification, and any examples that have substantially the same feature and demonstrate the same functions and effects as those in the technical concept described in claims of the present invention are included in the technical scope of the present invention.