DE3508266A1 - Process for the production of composite materials from metals and electroconductive polymers - Google Patents

Abstract

A process for production of composite materials from metals and electroconductive polymers in which the surface of the metal is treated with a metal-complexing agent, and the thus-treated metal is connected as the anode in a solution containing an anodically oxidisable monomer and a conductive salt, and the monomer is oxidized anodically so that it precipitates on the coated metals.

Description

Process for the manufacture of composites of metals and electrical

conductive Polvmeren Dle invention relates to a method for production of composites made of metals and electrically conductive polymers, in which one a metal treated with metal complexing agents and onto the metal treated in this way an electrically conductive layer through anodic polymerization of the monomers brings up.

According to the work of A.F. Diaz et al, J.C.S. Chem. Comm. 1979, p 635; J.C.S. Chem. Comm. 1979, page 854 and ACS Org. Coat. Plastic Chem. 43 (1980), are used in the anodic polymerization of pyrrole in the presence of conductive salts Films formed with electrical conductivities up to 102 S / cm. This acts they are p-type polypyrroles, with BF4-, C104- and HS04- are called.

For the use of electrically conductive polymers as a material for electrodes in secondary cells it is important that the active polymer mass is over contact is made with good conductive metals. This ensures that the active Polymer mass can be loaded and unloaded quickly and evenly. Try anodic polymerizable monomers, such as pyrrole or thiophene, by electrochemical oxidation to apply directly to aluminum or other base metals were unsuccessful, because the resulting polymer film does not adhere firmly to the metal.

The object of the invention is to provide a method of production of composites of metals and electrically conductive polymers which makes it possible to produce composites with good adhesion between metal and conductive Polymers, whereby it is also possible to use composite materials made of base metals, e.g. to manufacture aluminum and conductive polymers.

The object of the invention is achieved by a method of production of composites made up of metals and electrically conductive polymers by treating the surface of the metal with metal complexing agents and that way treated metal in a solution containing an anodically oxidizable monomer and a Contains conductive salt, switches as an anode and polymerizes the monomer anodically. Further Objects of the invention can be found in the detailed description below.

The process allows a firmly adhering two-component composite between metal and electrically conductive polymers. So it is e.g. possible to manufacture composite electrodes according to this process, where- at the metal serves as a conductor and one at the points with electrically conductive Polymers coated, which serve as an electrochemically active electrode material. For example, it is possible to use a particularly surface-rich, light base metal, e.g. expanded aluminum, as a conductor or as a support element for electrodes use. In this way, suitable electrodes are obtained that can be used in secondary cells can be found, whereby a particularly high energy density can be achieved.

Metals as they are usually suitable for the production of the composite materials are used as electrical conductors, e.g. copper and copper alloys. The method is particularly suitable for composites in which non-noble Metals are used, e.g.

Aluminum or aluminum alloys.

The surface of the metal is treated with a complexing agent. This can be done # by applying a solution of the complexing agent and the solvent evaporates. If the complexing agent is a liquid at room temperature, the complexing agent can also be applied without thinning. You can use the complexing agent but also add to the solution containing the monomers to be polymerized and the conductive salts contain.

Of the metal complexing agents are particularly those that able to form complexes with the metal used in each case.

Another way to get firmly adhering polymer coatings, is to use solutions of a monomer preferably on the metal surface from the class of the pyrroles and / or thiophenes with a conductive salt and a complexing agent to apply and then to oxidize anodically. The solvents used correspond to the systems commonly used in electrochemistry, e.g. acetonitrile, propylene carbonate, Dimethyl sulfoxide, these solvents and the process steps of the electrochemical Process are explained in more detail below.

Suitable complexing agents are, for example, organic molecules with functional Groups that can bind metals ionically and / or coordinatively: Morin Alizarin, Alizarin sulfonic acid and its alkali and ammonium salts, quinalizarin. Hydroxyfluorone, Diphenylcarbazid, Dipyridyl (2,2 ', 4,4'), Dimethylglyoxin, Hydroquinoline, Dithizon, Ctromotropic acid dioxime.

Such complexing agents are used as detection reagents for metals applied, see F. Feigl, Tüpfelanalyse, Akadem. Publishing House ('960 !, Frankfurt / Main.

Metal chelate complexing agents are e.g. in Houben-Weyl, Volume 6/2, page 41 to 61, Chelating Agents and Metal Chelates, F.P. Dwyer and D.P. Mellov, Academic Press NY 1964.

Morin is particularly suitable for aluminum and aluminum alloys, Alizarin and / or alizarin sulfonic acid.

The metal treated in this way is then immersed in a solution, which contains an anodically oxidizable monomer and a conductive salt, the treated Metal is connected as an anode and the monomer is anodically polymerized, so that the polymer layer grows on the metal.

Monomers that can be polymerized on the metal are e.g. Compounds from the class of the five-membered heterocyclic compounds with a conjugated # electron system the nitrogen, sulfur or oxygen as Heteroatom included. Examples of these compounds are those from the class of Pyrroles, the thiophenes and the furans. Of the pyrroles, the unsubstituted, for example, are suitable Pyrrole itself but also N-substituted pyrroles such as N-alkylpyrrole. But it can also other substituted pyrroles such as 3,4-dialkylpyrroles or 3,4-dichloropyrroles Find use. Of the compounds from the class of the thiophenes, particular ones are suitable the unsubstituted thiophene itself and 2- or 3-alkylthiophenes, z.8. 2,3-diethylthiophene. The unsubstituted furan also comes from the compounds of the class of the furans in question, but also alkylfurans such as 2-ethyl or 2,3-dimethylfuran. These mentioned five-membered heterocyclic compounds can also be used together with others copolymerizable compounds such as thiazole. Oxazole or imidazole, polymerized will.

The polymerization of these monomers takes place in the presence of conductive salts, which are also referred to as complexing agents or dopants. As conductive salts have e.g. KHS04, Na2SO #. HCOOH, LiClO4, HCl04, NEt4Cl04, NBu4Cl04, KAIF3, NaAlFs, KBF4, K2ZrF8, K2NiF4, N02P6, H2S041 FeCl3, NOPF6, KAsF6, NaPF6 or P-S03NH8u3 proven. The concentration of the conductive salts is such that 3 mol of the used Monomers or mixtures of the monomers at least 1 mole of those listed above Conductive salts are used.

Anions of aromatics with acidic groups, e.g. substituted ones, are also suitable aromatic sulfonic acids and polysulfonic acids. Conductive salts are particularly preferred containing benzenesulfonate or polylate anions.

The conductive salt concentration in the process is generally between 0.001 to 1, preferably 0.01 to 0.1 mol / l solvent.

The concentration of the monomer in the solvent is im generally around 0.1 moles per liter of solvent. But it can also be wide Limits are fallen below or exceeded. It is advisable to work with concentrations from 0.01 to 1 mole of monomer per liter of solvent.

Particularly suitable electrolyte solvents are those for the anodic Oxidation of the above-mentioned heterocyclic compounds customary polar organic Solvents that are able to dissolve the monomers and the conductive salt. The solvent itself should be as aprotic as possible.

Preference is given to alcohols, ethers, such as 1,2-dimethoxyethane, dioxane tetrahydrofuran, Acetone, acetonitrile, dimethylformamide or propylene carbonate.

The process can be carried out in an electrolytic cell or electrolysis machine with an external DC power source. The one with conductive polymers coated metal is connected as an anode.

The cathode can be made of another metal such as platinum, molybdenum, Tungsten or made of stainless steel, nickel or titanium.

The reaction temperature at which the process is operated has proved to be uncritical, so that work can be carried out in a wide range can, as long as the solidification temperature or the boiling point of the electrolyte solvent is not fallen below or exceeded. In general, the reaction temperature has proven to be a range from -20 to + 40 ° C has proven advantageous, with one normally works at room temperature (22 to 240C). In addition, the known, for Electrolysis conditions applied to such processes are complied with. Appropriate is the voltage at which the electrochemical polymerization is operated in Range from 1 to 150 volts, preferably in the range from 2 to 20 volts.

The current density is preferably from 0.5 to 100 mA / cm2 from 0.1 to 3.5 mA / cm2, proved to be advantageous. In general, one strives for thicknesses of the applied layer of conductive polymers between 10 and 100 .mu.m. the The thickness of the layer depends on the expiry time of the electrolyte solution. The received coated metals are then used to remove adhering solvents washed with solvent and dried. In the inventively produced In composites, the polymer lies as a complex cation of the polymer with the counter anion of the conductive salt. The electrical conductivity of the polymer is usually in the range from 10 to 102 S / cm. Such composites have various uses. she are used in particular as electrodes in elec- tric storage systems, such as batteries, used that can be worn. They can also be used as shielding material as semiconductor components or

find use as an electrical conductor.

The invention is illustrated in more detail by the following examples. The parts and percentages given in the examples are based on weight.

Example 1 An aluminum foil is treated with a 1% strength aqueous solution of Alizarin 5 (Nd salt of alizarinsulfonic acid) treated. After drying this will be treated aluminum foil (100 Am thickness) as an anode in a discontinuous electrolysis cell switched.

The electrolyte is acetonitrile 1500 parts with 13 parts conductive salt (~ -Sû3NBu3H). Within 30 '(current density 5 mAmp / cm2) with 2700 coulombs pyrrole as a polypyrrole film deposited; the deposited polypyrrole film is adherent and has a thickness from 37 am.

Comparison The procedure is as described in Example 1, but none In accordance with the invention, pretreatment of the aluminum foil is carried out, so there is no more firmly adhering closed polypyrrole film obtained.

Example * Complexing electrolyte firmly adhering medium film 2 Morin Acetonitrile / ~ -S03N8u3H + 3 quinalizarine propylene carbonate / LiClO # + 4 alizarine acetonitrile / # - SO3NBu3H + 5 hydroxyquinoline propylene carbonate / LiClO4 + * Reaction conditions as in example 1 Example 6 An acetonitrile solution consisting of 100 parts of acetonitrile and 10 parts Pyrrole, 3 parts of alizarin sulphonic acid are spread onto a 100 μm thick aluminum roll. After drying about 10 in air, 30 'in the drying cabinet (500C, 20 Torr) this so treated aluminum foil connected as anode and as described in example 1 - However, without alizarin S -polymerized; it becomes a sticky film t45 Am strong) obtained from polypyrrole on the aluminum.

Is worked as above (Example 6) and also still on the pyrrole omitted in the electrolyte, a firmly adhering but only approx.

Got 10 am thick film.

Claims (4)

Patent claim 1. Process for the production of composites from Metals and electrically conductive polymers, characterized in that the Surface of the metal treated with metal complexing agents and the treated in this way Metal in a solution, which is an anodically oxidizable monomer and a conductive salt contains, switches as an anode and polymerizes the monomer anodically. 2. The method according to claim 1, characterized in that one Anodically oxidized compound from the class of the pyrroles or the thiophenes. 3. The method according to claim 1, characterized in that aluminum or alloys containing aluminum are used as the metal layer. 4. The method according to claim 1, characterized in that one Metal surface with a mixture of a complexing agent, a monomer the class of the pyrroles and / or thiophenes and a conductive salt and optionally treated with a solvent and then anodically oxidized.