DE102013004526A1 - PEDOT / surfactant complexes - Google Patents

Abstract

The present invention relates to a method for producing a dispersion which contains complexes of a polythiophene and a surfactant, thiophene monomers being polymerized oxidatively in an aqueous phase in the presence of a surfactant by means of an organic peroxide. The present invention also relates to the dispersions obtainable by this process, a dispersion which contains complexes of a polythiophene and a surfactant, a process for producing an electrically conductive layer, the electrically conductive layer obtainable by this and the use of the dispersions according to the invention.

Description

The present invention relates to a process for producing a dispersion which includes complexes of a polythiophene and a surfactant, the dispersion obtainable by this process, a dispersion including complexes of a polythiophene and a surfactant, a process for producing an electroconductive layer, by this available electrically conductive layer and the use of the dispersions of the invention.

Conductive polymers are increasingly gaining in economic importance because polymers have advantages over metals in terms of processability, weight, and targeted chemical properties modification. Examples of known π-conjugated polymers are polypyrroles, polythiophenes, polyaniline, polyacetylenes, polyphenylenes and poly (p-phenylene-vinylenes). Layers of conductive polymers are used technically diverse, eg. B. as a polymeric counter electrode in capacitors or for the via of electronic circuit boards. The production of conductive polymers takes place chemically or electrochemically oxidatively from monomeric precursors, such as. B. optionally substituted thiophenes, pyrroles and anilines and their respective optionally oligomeric derivatives. In particular, the chemically oxidative polymerization is widespread because it is technically easy to implement in a liquid medium or on a variety of substrates.

A particularly important and technically used polythiophene is the example in the EP 0 339 340 A2 described poly (3,4-ethylenedioxythiophene) (PEDOT or PEDT), which is prepared by chemical polymerization of 3,4-ethylenedioxythiophene (EDOT or EDT) and which has very high conductivities in its oxidized form. A review of numerous poly (3,4-alkylenedioxythiophene) derivatives, in particular poly (3,4-ethylenedioxythiophene) derivatives, their monomeric building blocks, Syntheses and applications are given by L. Groenendaal, F. Jonas, D. Freitag, H. Pielartzik & JR Reynolds, Adv. Mater. 12, (2000) pp. 481-494 ,

Special technical significance, for example, in the EP 0 440 957 A2 disclosed dispersions of PEDOT with polyanions such. As polystyrene sulfonic acid (PSS) obtained. From these dispersions transparent, conductive films can be produced, which have found a variety of applications, for. B. as an antistatic coating or hole injection layer in organic light-emitting diodes (OLEDs) as in EP 1 227 529 A2 shown.

The polymerization of EDOT takes place in an aqueous solution of the polyanion, and a polyelectrolyte complex is formed. Cationic polythiophenes which contain polymeric anions as counterions for charge compensation are also often referred to in the art as polythiophene / polyanion complexes. Due to the polyelectrolyte properties of PEDOT as a polycation and PSS as a polyanion, this complex is not a real solution, but rather a dispersion. The extent to which polymers or parts of the polymers are dissolved or dispersed depends on the mass ratio of the polycation and the polyanion, on the charge density of the polymers, on the salt concentration of the environment and on the nature of the surrounding medium ( V. Kabanov, Russian Chemical Reviews 74, 2005, 3-20 ). The transitions can be fluent. Therefore, no distinction is made between the terms "dispersed" and "dissolved" below. Nor is there any distinction between "dispersion" and "solution" or between "dispersant" and "solvent". Rather, these terms are used in the following as synonymous.

Electrically conductive polymers are increasingly used in paint systems. However, since many coating systems are based on non-polar solvents, there is a great need for conductive polythiophenes which are dissolved or dispersed in nonpolar solvents. However, the disadvantage of the aqueous PEDOT / PSS dispersions known from the prior art is, inter alia, that the PEDOT / PSS complexes can be converted into an organic solvent system only with difficulty.

Furthermore, aqueous PEDOT / PSS dispersions are also used for the production of solid electrolyte layers in capacitors, such as those in the DE-A-10 2005 043829 is described. For this purpose, a porous electrode body of an electrode material (for example, aluminum or tantalum) is anodized to form a dielectric covering the surface of this electrode material, and then the porous body thus obtained is impregnated with a PEDOT / PSS dispersion. Drying then deposits a PEDOT / PSS layer as a solid electrolyte layer on the dielectric layer. However, the aqueous PEDOT / PSS dispersions known from the prior art are characterized by a comparatively high increase in viscosity with an increase in the solids content characterized the stepwise drying of the dispersions, resulting in a uniform coating of the pore walls with the conductive polymer in the in the DE-A-10 2005 043829 described method difficult.

To counteract the known from the prior art disadvantages of aqueous PEDOT / PSS dispersions, beat KR 10-0933441 B1 and KR 10-2009-012790 A instead of using polystyrenesulfonic surfactants such as sodium lauryl sulfonate as counterions of cationic polythiophenes. According to the teaching of these two publications, complexes of a polythiophene and an anionic surfactant are prepared in which the thiophene monomers are polymerized in the presence of such surfactants by means of sodium peroxodisulfate as the oxidant. The disadvantage of this method, however, is that the dispersions obtained in this way do not have sufficient storage stability and precipitations are observed in these dispersions after a short time.

It is an object of the present invention to overcome the disadvantages of the prior art in connection with the preparation of dispersions comprising conductive polymers, preferably including polythiophenes.

In particular, the present invention has the object to provide a method for producing a polythiophene-containing dispersion or generally polythiophene-containing dispersion, wherein the electrically conductive polythiophenes contained in the dispersion can be as simple as possible to convert into organic solvent systems. In addition, the dispersions obtainable by this process should be distinguished by an improved storage stability compared to the dispersions known from the prior art.

It was also the object of the present invention to provide a process for preparing a dispersion containing polythiophenes or dispersion containing generally polythiophenes, wherein the dispersions are preferably also characterized in that they are characterized by the lowest possible increase in the viscosity during the stepwise drying of the dispersion ,

A contribution to the solution of the abovementioned objects is afforded by a process for preparing a dispersion which comprises complexes of a polythiophene, preferably poly (3,4-ethylenedioxythiophene), and a surfactant, thiophene monomers being used in an aqueous phase in the presence of a surfactant an organic peroxide are oxidatively polymerized.

Surprisingly, it has been found that, in particular in the use of organic peroxides in the oxidative polymerization of thiophenes in the presence of surfactants, especially in the presence of anionic surfactants containing a sulfonate group or a sulfate group, particularly storage stable dispersions containing complexes and the polythiophenes get the surfactants.

in der
R₁ und R₂ unabhängig voneinander jeweils für H, einen gegebenenfalls substituierten C₁-C₁₈-Alkylrest oder einen gegebenenfalls substituierten C₁-C₁₈-Alkoxyrest, R₄ und R₅ zusammen für einen gegebenenfalls substituierten C₁-C₈-Alkylenrest, worin ein oder mehrere C-Atom(e) durch ein oder mehrere gleiche oder unterschiedliche Heteroatome ausgewählt aus O oder S ersetzt sein können, bevorzugt einen C₁-C₈-Dioxyalkylenrest, einen gegebenenfalls substituierten C₁-C₈-Oxythiaalkylenrest oder einen gegebenenfalls substituierten C₁-C₈-Dithiaalkylenrest, oder für einen gegebenenfalls substituierten C₁-C₈-Alkylidenrest, worin gegebenenfalls wenigstens ein C-Atom durch ein Heteroatom ausgewählt aus O oder S ersetzt ist, stehen.Preferred polythiophenes according to the invention are those having repeating units of the general formula (I)

in the
R ₁ and R ₂ independently of one another are each H, an optionally substituted C ₁ -C ₁₈ -alkyl radical or an optionally substituted C ₁ -C ₁₈ -alkoxy radical, R ₄ and R ₅ together represent an optionally substituted C ₁ -C ₈ -alkylene radical in which one or more carbon atom (s) may be replaced by one or more identical or different heteroatoms selected from O or S, preferably a C ₁ -C ₈ -dioxyalkylene radical, an optionally substituted C ₁ -C ₈ -Oxythiaalkylenrest or a optionally substituted C ₁ -C ₈ -dithiaalkylene radical, or an optionally substituted C ₁ -C ₈ -alkylidene radical, wherein optionally at least one C-atom is replaced by a heteroatom selected from O or S.

worin
A für einen gegebenenfalls substituierten C₁-C₅-Alkylenrest, bevorzugt für einen gegebenenfalls substituierten C₂-C₃-Alkylenrest steht,
Y für O oder S steht,
R₃ für einen linearen oder verzweigten, gegebenenfalls substituierten C₁-C₁₈-Alkylrest, bevorzugt linearen oder verzweigten, gegebenenfalls substituierten C₁-C₁₄-Alkylrest, einen gegebenenfalls substituierten C₅-C₁₂-Cycloalkylrest, einen gegebenenfalls substituierten C₆-C₁₄-Arylrest, einen gegebenenfalls substituierten C₇-C₁₈-Aralkylrest, einen gegebenenfalls substituierten C₇-C₁₈-Alkarylrest, einen gegebenenfalls substituierten C₁-C₄-Hydroxyalkylrest oder einen Hydroxylrest steht, und
y für eine ganze Zahl von 0 bis 8, bevorzugt für 0, 1 oder 2, besonders bevorzugt für 0 oder 1, steht, und
wobei für den Fall, dass mehrere Reste R₃ an A gebunden sind, diese gleich oder unterschiedlich sein können. Die allgemeine Formeln (I-a) ist dabei so zu verstehen, dass der Substituent R₃ y-mal an den Alkylenrest A gebunden sein kann. Particular preference is given to polythiophenes containing recurring units of the general formula (Ia) and / or (Ib)

wherein
A represents an optionally substituted C ₁ -C ₅ -alkylene radical, preferably an optionally substituted C ₂ -C ₃ -alkylene radical,
Y stands for O or S,
R _{3 is} a linear or branched, optionally substituted C ₁ -C ₁₈ -alkyl radical, preferably linear or branched, optionally substituted C ₁ -C ₁₄ -alkyl radical, an optionally substituted C ₅ -C ₁₂ -cycloalkyl radical, an optionally substituted C ₆ - C ₁₄ aryl radical, an optionally substituted C ₇ -C ₁₈ aralkyl radical, an optionally substituted C ₇ -C ₁₈ alkaryl radical, an optionally substituted C ₁ -C ₄ hydroxyalkyl radical or a hydroxyl radical, and
y is an integer from 0 to 8, preferably 0, 1 or 2, more preferably 0 or 1, and
in the case where several radicals R ₃ are bonded to A, they may be the same or different. The general formulas (Ia) is understood to mean that the substituent R ₃ may be bonded y times to the alkylene radical A.

worin R₃ und y die oben genannte Bedeutung haben.In further very particularly preferred embodiments of the process according to the invention, the polythiophenes are those containing recurring units of the general formula (I-aa) and / or the general formula (I-ab)

wherein R ₃ and y have the abovementioned meaning.

In still further highly preferred embodiments of the process according to the invention, the polythiophenes are those containing recurring units of the general formula (I-aaa) and / or the general formula (I-aba)

For the purposes of the invention, the prefix "poly" is understood to mean that more than one, identical or different, repeating unit is contained in the polythiophene. The polythiophenes contain a total of n repeating units of the general formula (I), where n can be an integer from 2 to 2000, preferably 2 to 100. The repeating units of general formula (I) may be the same or different within each polythiophene. Preference is given to polythiophenes containing in each case identical recurring units of the general formula (I).

At the end groups, the polythiophenes preferably carry H.

In particularly preferred embodiments of the process according to the invention, the polythiophene having repeating units of the general formula (I) is poly (3,4-ethylenedioxythiophene), poly (3,4-ethyleneoxythiathiophene) or poly (thieno [3,4-b] thiophene, ie a homopolythiophene of recurring units of the formula (I-aaa), (I-aba) or (Ib) in which Y = S. Very particularly preferred polythiophene is poly (3,4-ethylenedioxythiophene).

The polythiophenes in the complexes are preferably cationic, with "cationic" referring only to those located on the polythiophene backbone. Depending on the substituent on the radicals R ₁ or R ₂ , the polythiophenes can carry positive and negative charges in the structural unit, the positive charges on the polythiophene main chain and the negative charges being optionally on the radicals R substituted by sulfonate or carboxylate groups. In this case, the positive charges of the polythiophene main chain can be partially saturated by the optionally present anionic groups on the radicals R. The positive charges are not shown in the formulas because they are delocalized mesomerically. However, the number of positive charges is at least 1 and at most n, where n is the total number of all repeating units (equal or different) within the polythiophene. To compensate for the positive charge according to the invention preferably use the sulfonate groups or sulfate groups of the surfactants used, which form the complexes together with the (cationic) polythiophenes.

der Verbindungen der Struktur (III)

oder einer Mischung aus mindestens zwei davon, wobei der Einsatz von Schwefelsäuredodecylester besonders bevorzugt ist.The surfactant used in the process of the invention is preferably an anionic surfactant, more preferably an anionic surfactant having a sulfonate group or a sulfate group. The surfactant is particularly preferably selected from the group consisting of dodecylsulfonic acid, octylsulfonic acid, dodecylsulfuric acid, dodecylbenzenesulfonate, lauryl ether sulfate, the compound of structure (II),

the compounds of structure (III)

or a mixture of at least two thereof, wherein the use of sulfuric acid dodecyl ester is particularly preferred.

Furthermore, it is particularly preferred according to the invention that the surfactant and the thiophene monomer in a weight ratio of surfactant: thiophene monomer in a range from 10: 1 to 1:10, particularly preferably in a range from 5: 1 to 1: 5 and am most preferably in the range of 2.5: 1 to 1: 1.

The organic peroxide used in the process according to the invention preferably has the structural formula ROOR in which R is a C ₁ -C ₂₀ -alkyl radical or a C ₂ -C ₂₀ -acyl radical (ie the organic peroxide is preferably a dialkyl peroxide or a diacyl peroxide), the two radicals R within the structural formula being identical or different can. According to the invention, the organic peroxide is particularly preferably selected from the group consisting of dibenzoyl peroxide, lauryl peroxide, tert-butyl peroxide or a mixture of at least two thereof, wherein the use of dibenzyl peroxide is the most preferred.

Preferably, the thiophene monomer and the organic peroxide are in a molar ratio thiophene monomer: organic peroxide in a range of 1: 0.5 to 1: 5, more preferably in a range of 1: 1.01 to 1: 2, 5, and most preferably in a range of 1: 1.1 to 1: 1.5.

• i) Bereitstellen einer wässrigen Phase beinhaltend das Tensid;
• ii) Zugabe der Thiophen-Monomere sowie des organischen Peroxides zu dieser wässrigen Phase;
• iii) oxidative Polymerisation der Thiophen-Monomere in Gegenwart des Tensides unter Erhalt einer Dispersion, welche Komplexe aus dem Polythiophen und dem Tensid beinhaltet.
• iv) ggf. zumindest teilweises Austauschen des Wassers in der Dispersion gegen ein organisches Lösungsmittel.

According to a preferred embodiment of the method according to the invention, this comprises the method steps:

• i) providing an aqueous phase containing the surfactant;
• ii) adding the thiophene monomers and the organic peroxide to this aqueous phase;
• iii) oxidatively polymerizing the thiophene monomers in the presence of the surfactant to obtain a dispersion comprising complexes of the polythiophene and the surfactant.
• iv) optionally at least partially replacing the water in the dispersion with an organic solvent.

In process step i), an aqueous phase containing the surfactant is first provided, wherein the concentration of the surfactant in the aqueous phase preferably in a range of 0.1 to 25 wt .-%, particularly preferably in a range of 0.5 to 10 wt %, and most preferably in a range of 1 to 5% by weight.

According to an advantageous embodiment of the method according to the invention are at least 50 mol%, more preferably at least 60 mol% and most preferably at least 75 mol% of the sulfonate groups or the sulfate groups of the surfactant used in the process, based on the sum of all in the process used surfactant sulfonate groups or sulfate groups, in protonated form. This can be achieved, for example, by treating a solution of an alkali metal salt of the surfactant with a suitable cation exchanger. The aqueous phase provided in process step i) preferably has a metal ion content of less than 1000 ppm, particularly preferably less than 500 ppm and most preferably less than 500 ppm, in each case based on the solids content of that provided in process step i) aqueous phase.

Before the addition of the thiophene monomers and the organic peroxide in process step ii), the aqueous phase provided in process step i) is preferably at least partially freed of dissolved oxygen, for example by degassing with inert gas, in particular with nitrogen.

In process step ii), the thiophene monomers and the organic peroxide are then added to this aqueous phase, wherein it is preferred first to add the thiophene monomers and then, with stirring, to gradually add the organic peroxide. In this connection it is also preferred to add the thiophene monomers and the organic peroxide to the aqueous phase under an inert gas atmosphere, in particular under an N ₂ atmosphere. Optionally, in addition to the organic peroxide also further, optionally inorganic oxidizing agents may be added, such as iron (III) sulfate.

The thiophene monomers used are those monomers which contain the polythiophenes comprising the recurring units of the general formula (I), (Ia), (Ib), (Iaa), (I-ab), (Iaaa) and (I-aba), with the use of 3,4-ethylenedioxythiophene being the thiophene monomer most preferred.

In process step iii), the thiophene monomers are then oxidatively polymerized in the presence of the surfactant to obtain a dispersion comprising complexes of the polythiophene and the surfactant, wherein the oxidative polymerization is preferably carried out at a temperature in a range of 15 to 100 ° C, more preferably in a range of 25 to 75 ° C for a period in a range of 1 to 120 hours, more preferably in a range of 10 to 48 hours while stirring the reaction mixture. Furthermore, it is preferred according to the invention that the pH of the aqueous phase during the oxidative polymerization of the thiophene monomers, each measured at a temperature of 20 ° C, less than 5.0, more preferably less than 3.5 and most preferably is less than 2.0.

After the process step iii), the dispersion can optionally be worked up even further. Thus, any remaining solids can be removed by filtration or dissolved cations and / or anions, in particular Na ⁺ or K ⁺ cations or SO ₄ ^2- anions, can be removed by ultrafiltration or dialysis.

If appropriate, after the process step iii) in a further process step iv) at least a part of the water contained in the dispersion can be exchanged for an organic solvent. Particularly suitable organic solvents are aliphatic alcohols such as methanol, ethanol, i-propanol and butanol, aliphatic ketones such as acetone and methyl ethyl ketone, aliphatic carboxylic esters such as ethyl acetate and butyl acetate, aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, heptane and cyclohexane, Chlorohydrocarbons such as dichloromethane, trichloromethane and 1,2-dichloroethane, aliphatic nitriles such as acetonitrile, aliphatic sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane, aliphatic carboxylic acid amides such as methylacetamide, dimethylacetamide, dimethylformamide or N-methylpyrrolidone, aliphatic and araliphatic ethers such as diethyl ether and anisole or mixtures of at least two of them. The replacement of the water with these organic solvents can be carried out in the case of water-immiscible organic solvents, for example by extraction of the aqueous dispersion with the organic solvent. In the case of water-miscible solvents, for example, a solvent exchange is possible by mixing the aqueous dispersion with the organic solvent and then removing at least some of the water, for example by distillation.

• (α1) eine gemäß der hierin beschriebenen Testmethode bestimmte Viskosität von höchstens 3 mPas, besonders bevorzugt von höchstens 2 mPas und am meisten bevorzugt von höchstens 1 mPas, wenn die Dispersion auf einen gemäß der hierin beschriebenen Testmethode bestimmten Feststoffgehalt von 2,0 Gew.-% oder von 5,0 Gew.-% eingestellt wird;
• (α2) das Integral der Viskosität der Dispersion, welche dargestellt ist als Funktion des Feststoffgehalts, im Integrationsbereich von 0,5 Gew.-% Feststoff bis 5 Gew.-% Feststoff ist kleiner als 15 mPas × %, besonders bevorzugt kleiner als 12,5 mPas × % und am meisten bevorzugt kleiner als 10,0 mPas × %, wobei die Viskosität mit einem Rheometer in mPas bei 20°C und einer Scherrate von 100 s^–1 und der Feststoffgehalt in Prozent bestimmt wird;
• (α3) einen gemäß der hierin beschriebenen Testmethode bestimmten Sulfat-Gehalt von höchstens 200 ppm, besonders bevorzugt von höchstens 150 ppm und am meisten bevorzugt von höchstens 100 ppm, wenn die Dispersion auf einen Feststoffgehalt von 2,0 Gew.-% eingestellt wird;
• (α4) einen gemäß der hierin beschriebenen Testmethode bestimmten Natrium-Gehalt von höchstens 1.000 ppm, besonders bevorzugt von höchstens 750 ppm und am meisten bevorzugt von höchstens 500 ppm, wenn die Dispersion auf einen Feststoffgehalt von 2,0 Gew.-% eingestellt wird;
• (α5) eine gemäß der hierin beschriebenen Testmethode bestimmte Filtrierbarkeit über einen 0,45 μm-Filter nach einer Lagerung der Dispersion für einen Zeitraum von 7 Tagen bei einer Temperatur von 20°C von mindestens 50%, besonders bevorzugt von mindestens 75% und am meisten bevorzugt von mindestens 90%, jeweils wenn die Dispersion vor der Filtration auf einen Feststoffgehalt von 2,0 Gew.-% eingestellt wird;
• (α6) einen gemäß der hierin beschriebenen Testmethode bestimmten pH-Wert kleiner als 5,0, besonders bevorzugt kleiner als 3,5 und am meisten bevorzugt kleiner als 2,0.

A contribution to the solution of the abovementioned objects is also afforded by a dispersion comprising complexes of a polythiophene and a surfactant obtainable by the process according to the invention. Preferably, this dispersion realizes at least one of the following properties, but particularly preferably all the following properties:

• (α1) a viscosity, determined according to the test method described herein, of at most 3 mPas, more preferably of at most 2 mPas and most preferably of at most 1 mPas, if the dispersion has a solids content of 2.0% by weight determined according to the test method described herein. % or of 5.0 wt .-% is set;
• (α2) the integral of the viscosity of the dispersion, which is represented as a function of the solids content, in the integration range from 0.5% by weight of solid to 5% by weight of solid is less than 15 mPas ×%, particularly preferably less than 12, 5 mPas ×% and most preferably less than 10.0 mPas ×%, wherein the viscosity is determined with a rheometer in mPas at 20 ° C and a shear rate of 100 s ^-1 and the solids content in percent;
• (α3) a sulphate content of at most 200 ppm, more preferably at most 150 ppm and most preferably at most 100 ppm, determined according to the test method described herein, when the dispersion is adjusted to a solids content of 2.0% by weight;
• (α4) a sodium content of at most 1,000 ppm, more preferably at most 750 ppm and most preferably at most 500 ppm, determined according to the test method described herein, when the dispersion is adjusted to a solids content of 2.0% by weight;
• (α5) a filterability determined according to the test method described herein via a 0.45 μm filter after storage of the dispersion for a period of 7 days at a temperature of 20 ° C of at least 50%, more preferably of at least 75% and most preferably at least 90%, each time the dispersion is adjusted to a solids content of 2.0% by weight before filtration;
• (α6) has a pH determined in accordance with the test method described herein of less than 5.0, more preferably less than 3.5, and most preferably less than 2.0.

The adjustment to a solids content of 2.0 wt .-% in connection with the properties (α3), (α4) and (α5) can be carried out by the skilled person known manner, i. e. by dilution (in the case of dispersions having a solids content> 2% by weight) or by evaporation (in the case of dispersions having a solids content <2% by weight).

Dispersions preferred according to the invention are those which realize the following properties or combinations of properties: (α1), (α2), (α3), (α4), (α5), (α6), (α1) (α2), (α1) ( α3), (α1) (α4), (α1) (α5), (α1) (α6), (α2) (α3), (α2) (α4), (α2) (α5), (α2) (α6 ), (α3) (α4), (α3) (α5), (α3) (α6), (α4) (α5), (α4) (α6), (α5) (α6), (α3) (α5) and (α1) (α2) (α3) (α4) (α5) (α6).

• (α1) eine gemäß der hierin beschriebenen Testmethode bestimmte Viskosität von höchstens 3 mPas, besonders bevorzugt von höchstens 2 mPas und am meisten bevorzugt von höchstens 1 mPas, wenn die Dispersion auf einen gemäß der hierin beschriebenen Testmethode bestimmten Feststoffgehalt von 2,0 Gew.-% oder von 5,0 Gew.-% eingestellt wird;
• α2) das Integral der Viskosität der Dispersion, welche dargestellt ist als Funktion des Feststoffgehalts, im Integrationsbereich von 0,5 Gew.-% Feststoff bis 5 Gew.-% Feststoff ist kleiner als 15,0 mPas × %, besonders bevorzugt kleiner als 12,5 mPas × % und am meisten bevorzugt kleiner als 10,0 mPas × %, wobei die Viskosität mit einem Rheometer in mPas bei 20°C und einer Scherrate von 100 s^–1 und der Feststoffgehalt in Prozent bestimmt wird;
• (α3) einen gemäß der hierin beschriebenen Testmethode bestimmten Sulfat-Gehalt von höchstens 200 ppm, besonders bevorzugt von höchstens 150 ppm und am meisten bevorzugt von höchstens 100 ppm, wenn die Dispersion auf einen Feststoffgehalt von 2,0 Gew.-% eingestellt wird;
• (α4) einen gemäß der hierin beschriebenen Testmethode bestimmten Natrium-Gehalt von höchstens 1.000 ppm, besonders bevorzugt von höchstens 750 ppm und am meisten bevorzugt von höchstens 500 ppm, wenn die Dispersion auf einen Feststoffgehalt von 2,0 Gew.-% eingestellt wird;
• (α5) eine gemäß der hierin beschriebenen Testmethode bestimmte Filtrierbarkeit über einen 0,45 μm-Filter nach einer Lagerung der Dispersion für einen Zeitraum von 7 Tagen bei einer Temperatur von 20°C von mindestens 50%, besonders bevorzugt von mindestens 75% und am meisten bevorzugt von mindestens 90%, jeweils wenn die Dispersion vor der Filtration auf einen Feststoffgehalt von 2,0 Gew.-% eingestellt wird;
• (α6) einen gemäß der hierin beschriebenen Testmethode bestimmten pH-Wert kleiner als 5,0, besonders bevorzugt kleiner als 3,5 und am meisten bevorzugt kleiner als 2,0.

A contribution to the solution of the abovementioned objects is also afforded by a dispersion comprising complexes of a polythiophene and a surfactant, the dispersion realizing at least one of the following properties, but preferably all the following properties:

• (α1) a viscosity, determined according to the test method described herein, of at most 3 mPas, more preferably of at most 2 mPas and most preferably of at most 1 mPas, if the dispersion has a solids content of 2.0% by weight determined according to the test method described herein. % or of 5.0 wt .-% is set;
• α2) the integral of the viscosity of the dispersion, which is shown as a function of the solids content, in the integration range of 0.5 wt .-% solids to 5 wt .-% solids is less than 15.0 mPas ×%, more preferably less than 12 , 5 mPas ×% and most preferably less than 10.0 mPas ×%, wherein the viscosity is determined with a rheometer in mPas at 20 ° C and a shear rate of 100 s ^-1 and the solids content in percent;
• (α3) a sulphate content of at most 200 ppm, more preferably at most 150 ppm and most preferably at most 100 ppm, determined according to the test method described herein, when the dispersion is adjusted to a solids content of 2.0% by weight;
• (α4) a sodium content of at most 1,000 ppm, more preferably at most 750 ppm and most preferably at most 500 ppm, determined according to the test method described herein, when the dispersion is adjusted to a solids content of 2.0% by weight;
• (α5) a filterability determined according to the test method described herein via a 0.45 μm filter after storage of the dispersion for a period of 7 days at a temperature of 20 ° C of at least 50%, more preferably of at least 75% and most preferably at least 90%, each time the dispersion is adjusted to a solids content of 2.0% by weight before filtration;
• (α6) has a pH determined in accordance with the test method described herein of less than 5.0, more preferably less than 3.5, and most preferably less than 2.0.

Dispersions preferred according to the invention are in turn those which realize the following properties or combinations of properties: (α1), (α2), (α3), (α4), (α5), (α6), (α1) (α2), (α1) (α3), (α1) (α4), (α1) (α5), (α1) (α6), (α2) (α3), (α2) (α4), (α2) (α5), (α2) ( α6), (α3) (α4), (α3) (α5), (α3) (α6), (α4) (α5), (α4) (α6), (α5) (α6), (α3) (α5 ) and (α1) (α2) (α3) (α4) (α5) (α6).

Preferred polythiophenes and surfactants are those polythiophenes and surfactants which have already been mentioned as preferred polythiophenes or surfactants in connection with the process according to the invention for preparing the dispersions. The same applies to the weight ratio of surfactant to polythiophenes. In the complexes of the present invention, it is preferably in a range of 10: 1 to 1:10, more preferably in a range of 5: 1 to 1: 5, and most preferably in a range of 2.5: 1 to 1: 1.

• I) Bereitstellung eines Substrates;
• II) Aufbringen einer durch das erfindungsgemäße Verfahren erhältlichen Dispersion oder einer erfindungsgemäßen Dispersion auf das Substrat;
• III) zumindest teilweises Entfernen des Wassers bzw. des organischen Lösungsmittels aus der Dispersion unter Erhalt einer elektrisch leitfähigen Schicht auf dem Substrat.

A contribution to achieving the abovementioned objects is also made by a method for producing an electrically conductive layer, comprising the method steps:

• I) providing a substrate;
• II) applying a dispersion obtainable by the process according to the invention or a dispersion according to the invention to the substrate;
• III) at least partially removing the water or the organic solvent from the dispersion to obtain an electrically conductive layer on the substrate.

In method step I), a substrate is initially provided, the type of substrate depending on the intended use of the dispersion according to the invention. If the dispersion according to the invention is used, for example, for producing a solid electrolyte layer in a capacitor, the substrate may be, for example, a porous anode body provided with a dielectric layer. If the dispersion is used, for example, to produce a hole injection layer in an OLED, the substrate can be, for example, a transparent electrode such as ITO. Also suitable as substrates are in particular films, particularly preferably polymer films, very particularly preferably polymer films made from thermoplastic polymers, or glass plates.

In process step II), a dispersion obtainable by the process according to the invention or a dispersion according to the invention is then applied to the substrate, this application being carried out by known processes, e.g. As by spin coating, impregnation, casting, dripping, spraying, spraying, knife coating, brushing or printing, for example by ink-jet, screen, gravure, offset or pad printing in a wet film thickness of, for example, 0.5 microns to 250 microns , preferably in a wet film thickness of 2 microns to 50 microns can be done.

In method step III), at least some of the water or organic solvent is then removed from the dispersion to obtain an electrically conductive layer on the substrate, this removal preferably being effected by drying the dispersion-coated substrate at a temperature in the range of 20 ° C to 200 ° C takes place.

A contribution to the solution of the abovementioned objects is also provided by an electrically conductive layer which can be obtained by the method described above. Preferably, such an electrically conductive layer is characterized by a conductivity of at least 1 S / cm, more preferably at least 2 S / cm, and most preferably at least 4 S / cm.

The use of a dispersion or a dispersion according to the invention for the antistatic coating obtainable by the process according to the invention, for producing a conductive layer in a condenser, in particular for producing a solid electrolyte layer or a polymer outer layer applied to a solid electrolyte layer, also contributes to the solution of the abovementioned problems a capacitor for producing a hole injection layer in an OLED or an OPV or for producing an IR reflection layer.

The invention will now be explained in more detail by means of test methods and non-limiting examples.

TEST METHODS

Determination of conductivity

A cleaned glass substrate was placed on a spin coater and 10 ml of the composition of the invention was spread on the substrate. Subsequently, the supernatant solution was spun off by rotation of the plate. Thereafter, the thus coated substrate was dried at 130 ° C for 15 minutes on a hot plate. The layer thickness was determined with the aid of a layer thickness gauge. (Tencor, Alphastep 500). The conductivity was determined by evaporating over a shadow mask Ag electrodes 2.5 cm in length at a distance of 10 mm. The surface resistance determined with an electrometer (Keithly 614) was multiplied by the layer thickness to obtain the electrical resistivity. The conductivity corresponds to the reciprocal of the electrical resistivity.

Determination of viscosity

The viscosity was determined using a Haake RV 1 rheometer with attached cryostat. For this purpose, a double-gap DG 43 measuring cup and a DG 43 rotor, both from Haake, were used. 12 g of the aqueous solution are weighed into the measuring cup. The temperature was controlled by cryostat to 20 ° C. To control the temperature of the dispersion was first tempered for 240 seconds at a Scheerrate of 50 s ^-1 . Subsequently, the Scheerate was increased to 700 s ^-1 . It was 30 seconds at this Scheer rate. Then, 30 viscosity measurements are taken at a shear rate of 100 s ^-1 for a further 30 seconds (1 measured value / second). The mean of these 30 readings is the viscosity value of the dispersion.

Determination of the integral of the viscosity

The integral of the viscosity as a function of the solids content is determined as follows: First, the viscosity of the dispersion at various solids contents in the range 0.5% to 5% with a rheometer in mPas at 20 ° C and a shear rate of 100 s ^-1 determined. The solids content is changed by addition or evaporation of the dispersant. In order to determine the integral with a sufficient accuracy, for each of the percentage ranges, 0.5% to less than 1%, 1% to less than 2%, 2% to less than 3%, 3% to less than 4%, 4% to less 5% and 5% determines the viscosity at least for a solids content. From the viscosity values for a given solids content, the integral of the viscosity in the integration range 0.5% to 5% is calculated according to known rules of mathematics. This can be done for example through the tendon trapezoidal rule: If the viscosity h, for example, each have a solids content x _i determined from the above six percent areas, then the area A _i of the trapezoid results in between two adjacent values of h (x _i) and h (x _{i + 1} ) about the formula:

The integral I then results from the sum of the individual trapezoidal areas:

Determination of sodium and sulfate content

The determination of Na ⁺ - and SO ₄ ^2- -content was performed by ion chromatography (Apparatus used: Metrohm 882 Compact IC Plus; Utilized program: Metrohm MagIC Net ^®).

Determination of the solids content (FG)

A weighing jar (d = 50 mm) with lid was weighed empty (weight A). Then 5 g of the substance to be tested was weighed (weight B) and dried in a drying oven at 100 ° C for 16 h. After removal from the oven, the sample was immediately capped and weighed (weight C). The solids content is calculated as follows: Solids content = 100% × (C - A) / (B - A).

A double determination was always carried out (maximum deviation 0.03%) and the mean value indicated.

Determination of pH]

The pH value was determined using a pH meter (combination electrode, glass electrode) at a temperature of 20 ° C.

Determination of filterability (to assess the stability of a dispersion) The sample to be considered is adjusted to a solids content of 2% by weight. 10 ml of the sample are stored as a reference sample, 10 ml are filtered by hand using a 10 ml syringe through a 0.45 μm syringe filter from PALL (article number 16NPG004-02JVA), this is the reference sample.

First, from the reference sample the light absorption in the spectral range of 950-1050 nm is determined as the mean value over this absorption range, the solids content in the dispersion being adjusted by dilution such that the mean absorption of the reference is approximately 0.4-0.5. The average of the light absorption over the spectral range of 950-4050 nm (layer thickness: 0.01 mm) is referred to below as the "mean absorption of the reference sample" (A _Ref ).

Subsequently, the same amount of solvent is added to the comparative sample as to the reference sample, and then the mean value of the light absorption over the spectral range of 950-1050 nm is determined again for the same layer thickness (A - _Vergl ).

As semi-quantitative measure of filterability is defined:

EXAMPLE 1

Preparation of a dodecylsulfuric acid stock solution

Sodium dodecyl sulfate (18 g, 0.063 mol) was dissolved in H ₂ O (750 g), added with Lewatit S 108 H (31 mL) and stirred for 15 min. The Lewatit was removed by filtration through cotton wool and washed with H ₂ O (250 g). 960 ml of stock solution were obtained. FG = 1.78%; Na content: 311 ppm. This corresponds to 49.5 mmol (79%) of dodecylsulfuric acid, 13.5 mmol of sodium dodecyl sulfate (21%) per 960 ml. The stock solution was freshly prepared before each experiment.

EXAMPLE 2

960 g of the freshly prepared dodecylsulfuric acid stock solution from Example 1 were transferred to a three-necked flask with KPG stirrer, degassed with N ₂ (passage of N ₂ for 30 minutes) and under an N ₂ atmosphere, 3,4-ethylenedioxythiophene (11, 2 g, 0.079 mol). While stirring, dibenzoyl peroxide (29.07 g, 0.09 mol, Luperox A 75, 75% in H ₂ O) was added in portions over a period of 2 h and the mixture was stirred at 60 ° C. for 24 h (pH of the reaction solution : pH = 1). The resulting dispersion was filtered through a fluted filter and purified by ultrafiltration. 1000 g of water were added to 1,000 g of the dispersion and pumped along a 50 nm pore size membrane (Pall Schumasiv) until the volume was reduced to 1,000 g. The permeate was discarded. This process was repeated three times. After filtration through a 0.45 μm syringe filter (PVDF), the analytical data (see below) were collected. Finally, the mixture was filtered through a 0.2 μm filter (nylon-66, depth filter "Junior", Amazon, 16NPG002-02JVA) (FG = 0.29).

The filterability of the freshly prepared dispersion was 109% (in the case of filtration, more solvent than solids is retained, so that a value> 100% results). After 7 days storage of the dispersion at 20 ° C, the filterability is determined again. A value of 100% was obtained. Solids content [%] Viscosity [mPas] pH Na [ppm] SO ₄ [ppm] 0.6 1 1.5 209 74

EXAMPLE 3

200 g of the dispersion from Example 2 were concentrated to 47.3 g and filtered through a 0.2 μm syringe filter (PVDF). Solids content [%] Viscosity [mPas] pH Na [ppm] SO ₄ [ppm] 1.81 1.6 1.5 1491 520

EXAMPLE 4

960 g of the freshly prepared dodecylsulfuric acid stock solution from Example 1 were transferred to a three-necked flask with KPG stirrer, degassed with N ₂ and 3,4-ethylenedioxythiophene (11.2 g, 0.079 mol) was added under an N ₂ atmosphere. After addition of iron (III) sulfate (200 mg), dibenzoyl peroxide (29.1 g, 0.09 mol, Luperox A 75, 75% in H ₂ O) was added portionwise with stirring over a period of 2 h, and it became 24 h stirred at room temperature. The resulting dispersion was filtered through a fluted filter and purified by ultrafiltration (1000 g of water was added to 1,000 g of water and pumped along a 50 nm pore size membrane (Pall Schumasiv) until the volume was reduced to 1000 g discarded.

This process was repeated three times. Finally, the mixture was filtered through a 0.2 μm filter (nylon-66, depth filter "Junior", Amazon, 16NPG002-02JVA). Solids content [%] Conductivity [S / cm] Layer thickness [nm] 0.53 4 29

EXAMPLE 5

150 g of the dispersion from Example 4 were evaporated to 50 ml (solids content 2.1%). Solids content [%] Viscosity [mPas] Na [ppm] SO ₄ [ppm] 2.1 1 877 154

EXAMPLE 6

279 g of the dispersion from Example 2 were concentrated to 45 g and filtered through a 0.2 μm syringe filter (PVDF). Solids content [%] Viscosity [mPas] pH Conductivity [S / cm] 5.8 3.1 1.7 27

COMPARATIVE EXAMPLE (Sodium peroxodisulfate as oxidizer)

100 g of the freshly prepared dodecylsulfuric acid stock solution from Example 1 were transferred to a three-necked flask with magnetic stirrer, degassed with N ₂ and under N ₂ atmosphere was added 3,4-ethylenedioxythiophene (1.12 g, 0.0079 mol). Then, sodium peroxodisulfate (2.14 g, 0.009 mol) was added and the reaction mixture was heated to 60 ° C for 24 h. The dark blue dispersion was filtered immediately after the reaction through a 280 μm fast sieve. After a period of 1 h, the initially homogeneous, blue dispersion separated into a black-blue solid and a yellow, clear solution. After this time no absorption measurements could be made on the heterogeneous substance mixture.

Filtration of a 10 ml. Sample directly after the reaction through a 1 micron folded filter gave a clear, pale yellow solution (FG 3.17 wt.%, Especially Na ₂ SO ₄ ), the blue solid (PEDOT / surfactant complex ) was completely restrained. The average absorption of the filtrate in the spectral range of 950-1050 nm was only 10% compared to the product from Example 2 (with the same filtration method and dilution).

Another 50 ml were treated immediately after the reaction with cation exchanger and anion exchanger, which were each removed after 15 min stirring by filtration through cotton wool. After just a few minutes of standing, it was observed that the dispersion separated into a blue solid and a clear yellow solution. After filtration (performed immediately after the ion exchange treatment) over a 1 μm syringe filter, the solid content of the clear, yellow filtrate was 1.36 wt%, the blue solid was completely retained.

An identical result was obtained when the reaction with sodium dodecyl sulfate (instead of dodecylsulfuric acid) was conducted under Fe (III) SO ₄ catalysis at room temperature.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0339340 A2 [0003]
• EP 0440957 A2 [0004]
• EP 1227529 A2 [0004]
• DE 102005043829 A [0007, 0007]
• KR 10-0933441 B1 [0008]
• KR 10-2009-012790 A [0008]

Cited non-patent literature

• Syntheses and applications are given by L. Groenendaal, F. Jonas, D. Freitag, H. Pielartzik & JR Reynolds, Adv. Mater. 12, (2000) pp. 481-494 [0003]
• V. Kabanov, Russian Chemical Reviews 74, 2005, 3-20 [0005]

Claims (19)

A process for preparing a dispersion comprising complexes of a polythiophene and a surfactant, wherein thiophene monomers are oxidatively polymerized in an aqueous phase in the presence of a surfactant by means of an organic peroxide. Method according to claim 1, comprising the method steps: i) providing an aqueous phase containing the surfactant; ii) adding the thiophene monomers and the organic peroxide to this aqueous phase; iii) oxidatively polymerizing the thiophene monomers in the presence of the surfactant to obtain a dispersion comprising complexes of the polythiophene and the surfactant; iv) optionally at least partially replacing the water in the dispersion with an organic solvent. The method of claim 1 or 2, wherein the concentration of the surfactant in the aqueous phase provided in step i) is in a range of 0.1 to 25 wt .-%. A method according to claim 2 or 3, wherein the aqueous phase provided in step i) has a metal ion content of less than 1000 ppm, based on the total weight of the aqueous phase provided in step i). A method according to any one of the preceding claims, wherein the surfactant and the thiophene monomer are used in a weight ratio of surfactant: thiophene monomer in the range of 10: 1 to 1:10. A method according to any one of the preceding claims, wherein the surfactant is an anionic surfactant. The method of claim 6, wherein the anionic surfactant comprises a sulfonate group or a sulfate group. A process according to claim 5 or 6, wherein the surfactant is selected from the group consisting of dodecylsulfonic acid, octylsulfonic acid, dodecylsulfonate, dodecylbenzenesulfonate, lauryl ether sulfate, the compound of structure (II),

the compound of structure (IV)

or a mixture of at least two of them. A process as claimed in claim 7 or 8, wherein at least 50 mol% of the sulfonate groups or the sulfate groups of the surfactant used in the process, based on the sum of all surface-active sulfonate groups or sulfate groups used in the process, are present in protonated form , A process according to any one of the preceding claims wherein the pH of the aqueous phase is less than 5.0 during the oxidative polymerization of the thiophene monomers. A process according to any one of the preceding claims, wherein the organic peroxide has the structural formula ROOR in which R is a C ₁ -C ₂₀ -alkyl radical or a C ₂ -C ₂₀ -acyl radical and where the two radicals R within the structural formula may be identical or different. The method of claim 11 wherein the organic peroxide is selected from the group consisting of dibenzoyl peroxide, lauryl peroxide, tertiary butyl peroxide, or a mixture of at least two thereof. A dispersion comprising complexes of a polythiophene and a surfactant obtainable by the process of any one of claims 1 to 12. A dispersion according to claim 13, wherein the dispersion achieves at least one of the following properties: (α1) a viscosity of at most 3 mPas determined according to the test method described herein when the dispersion is tested for a solids content of 2.0% by weight determined according to the test method described herein. % or of 5.0 wt .-% is set; (α2) is the integral of the viscosity of the dispersion represented as a function of solids content in the integration range from 0.5% by weight% solids to 5% weight% solids is less than 15.0 mPas ×%, where the viscosity is determined with a rheometer in mPas at 20 ° C and a shear rate of 100 s ^-1 and the solids content in percent; (α3) a sulphate content of at most 200 ppm determined according to the test method described herein when the dispersion is adjusted to a solids content of 2.0% by weight; (α4) a sodium content of at most 1,000 ppm determined according to the test method described herein when the dispersion is adjusted to a solids content of 2.0% by weight; (α5) a filterability determined according to the test method described herein of a 0.45 μm filter after storage of the dispersion for a period of 7 days at a temperature of 20 ° C of at least 50%, if the dispersion before filtration to a Solids content of 2.0 wt .-% is set; (α6) has a pH determined in accordance with the test method described herein of less than 5.0. A dispersion comprising complexes of a polythiophene and a surfactant, wherein the dispersion achieves at least one of the following properties: (α1) a viscosity of at most 3 mPas determined according to the test method described herein, when the dispersion has a solids content determined according to the test method described herein of 2.0% by weight or 5.0% by weight; (α2) is the integral of the viscosity of the dispersion, which is represented as a function of solids content, in the integration range from 0.5% by weight of solid to 5% by weight of solid is less than 15.0 mPas ×%, where the viscosity with a rheometer in mPas at 20 ° C and a shear rate of 100 s ^{· 1} and the solids content in percent is determined; (α3) a sulphate content of at most 200 ppm determined according to the test method described herein when the dispersion is adjusted to a solids content of 2.0% by weight; (α4) a sodium content of at most 1,000 ppm determined according to the test method described herein when the dispersion is adjusted to a solids content of 2.0% by weight; (α5) a filterability determined according to the test method described herein of a 0.45 μm filter after storage of the dispersion for a period of 7 days at a temperature of 20 ° C of at least 50%, if the dispersion before filtration to a Solids content of 2.0 wt .-% is set; (α6) has a pH determined in accordance with the test method described herein of less than 5.0. A method for producing an electrically conductive layer, comprising the method steps: I) providing a substrate; II) applying a dispersion according to any one of claims 13 to 15 to the substrate; III) at least partially removing the water or the organic solvent from the dispersion to obtain an electrically conductive layer on the substrate. An electrically conductive layer obtainable by the method of claim 16. Use of the dispersions according to one of Claims 13 to 15 for the antistatic coating, for producing a conductive layer in a capacitor, for producing a hole injection layer in an OLED or an OPV or for producing an IR reflection layer. Use according to claim 18, wherein the conductive layer in a capacitor is a solid electrolyte layer or a polymeric outer layer applied to a solid electrolyte layer.