PROCESS FOR PRODUCING FUNCTIONALIZED POLYTHIOPHENES

Abstract

A process for producing a liquid composition comprising a functionalized -conjugated polythiophenes, comprising the process steps of i) providing a liquid phase comprising a functionalized -conjugated polythiophene that is dissolved or dispersed in a solvent, wherein the functionalized -conjugated polythiophene comprises repeating units of the general formula (I)

##STR00001## wherein X, Y are identical or different and are O, S, or NR.sup.1, wherein R.sup.1 is hydrogen or an aliphatic or aromatic residue having 1 to 18 carbon atoms; A is an organic residue carrying an anionic functional group; and wherein the liquid phase has a pH-value of less than 2.5; ii) adjusting the pH-value of the liquid phase provided in process step i) to a value in the range from 2.5 to 10 by the addition of a base.

The present invention also relates to a liquid composition obtainable by this process.

Claims

1. A process for producing a liquid composition comprising functionalized -conjugated polythiophenes, the process comprising the steps of i) providing a liquid phase comprising a functionalized -conjugated polythiophene that is dissolved or dispersed in a solvent, wherein the functionalized -conjugated polythiophene comprises repeating units of the general formula (I) ##STR00008## wherein X,Y are identical or different and are O, S, or NR.sup.1, wherein R.sup.1 is hydrogen or an aliphatic or aromatic residue having 1 to 18 carbon atoms; A is an organic residue carrying an anionic functional group; and wherein the liquid phase has a pH-value of less than 2.5; ii) adjusting the pH-value of the liquid phase provided in process step i) to a value in the range from 2.5 to 10 by the addition of a base.

2. The process according to claim 1, wherein the provision of the liquid phase in process step i) comprises the process steps of ia) providing a liquid reaction mixture comprising a) thiophene monomers of the general formula (I) ##STR00009## wherein X, Y and A are defined as in claim 1; b) an oxidizing agent; and c) a solvent; ib) oxidatively polymerizing the thiophene monomers of the general formula (I) in the liquid reaction mixture obtained in process step ia) to obtain a liquid phase comprising a functionalized -conjugated polythiophene; ic) optionally purification of the liquid phase obtained in process step ib), preferably by means of ion filtration.

3. The process according to claim 1, wherein in the general formula (I) X,Y are O, A is (CR.sup.2.sub.2).sub.mCR.sup.2R.sup.3(CR.sup.2.sub.2).sub.n, wherein residues R.sup.2 are independently from each other hydrogen or (CH.sub.2).sub.sZ(CR.sup.4.sub.2).sub.pSO.sub.3.sup.M.sup.+, R.sup.3 is (CH.sub.2).sub.sZ(CR.sup.4).sub.pSO.sub.3.sup.M.sup.+, Z is O, S or CH.sub.2, R.sup.4 is a hydrogen or an alkyl group; M.sup.+ is a cation, m and n are identical or different and are an integer from 0 to 3, s is an integer from 0 to 10 and p is an integer from 1 to 18.

4. The process according to claim 3, wherein in the general formula (I) X,Y are O, A is (CH.sub.2).sub.sCR.sup.2R.sup.3(CH.sub.2).sub.n, wherein R.sup.2 is hydrogen, R.sup.3 is (CH.sub.2)O(CH.sub.2).sub.pSO.sub.3.sup.M.sup.+, M.sup.+ is an inorganic cation, preferably Na.sup.+ or K.sup.+, n is 0 or 1, s is 0 or 1, and p is 4 or 5.

5. The process according to claim 3, wherein in the general formula (I) X, Y are O, A is (CH.sub.2).sub.sCR.sup.2R.sup.3(CH.sub.2).sub.n, wherein R.sup.2 is hydrogen, R.sup.3 is (CH.sub.2).sub.sOCH.sub.2CH.sub.2CHR.sup.4SO.sub.3.sup.M.sup.+, M.sup.+ is an inorganic cation, preferably Na.sup.+ or K.sup.+, R.sup.4 is CH.sub.3 or CH.sub.2CH.sub.3, preferably CH.sub.3, n is 0 or 1, s is 0 or 1, and p is 4 or 5.

6. The process according to claim 1, wherein the solvent is water.

7. The process according to claim 1, wherein the base is an inorganic base.

8. The process according to claim 7, wherein the inorganic base is an alkali metal hydroxide.

9. A liquid composition comprising functionalized -conjugated polythiophenes obtainable by the process according to claim 1.

10. A liquid composition having a pH-value in the range from 2.5 to 10 and comprising a functionalized -conjugated polythiophene that is dissolved or dispersed in a solvent, wherein the polythiophene comprises repeating units of the general formula (I) ##STR00010## wherein X, Y and A are as defined in claim 1 and wherein a composition that is obtained after drying the liquid composition at a temperature of 100 C. and a pressure of 50 mbar for 16 hours, fulfills at least one of the following conditions (A) to (E): (A) a weight loss of 10 wt.-%, based on the total weight of the dried liquid composition, at a temperature of not less than 300 C. as determined by means of thermogravimetric analysis; (B) a weight loss of 20 wt.-%, based on the total weight of the dried liquid composition, at a temperature of not less than 330 C. as determined by means of thermogravimetric analysis; (C) a weight loss of 30 wt.-%, based on the total weight of the dried liquid composition, at a temperature of not less than 345 C. as determined by means of thermogravimetric analysis; (D) absence of a peak in the derivative plot in the interval between 250 C. and 270 C.; (E) a ratio of the derivative value at 261 C. to the derivative value at the 2.sup.nd peak of 0.1 or less.

11. A process for the preparation of a layered body, comprising the process steps: I) provision of a substrate; II) application of the liquid composition according to claim 9 onto at least a part of at least one surface of the substrate; III) optionally at least partial removal of the solvent for the formation of a conductive layer that covers at least a part of at least one surface of the substrate.

12. The process according to claim 11, wherein the substrate is an electrode body of an electrode material, wherein a dielectric covers one surface of this electrode material at least partly under formation of an anode body.

13. Use of the liquid composition according to claim 9 for the preparation of a conductive layer in an electronic device.

14. The use according to claim 13, wherein the electronic device is selected from photoconductive cells, photoresistors, photoswitches, phototransistors, phototubes, IR detectors, photovoltaic device, solar cells, coating materials for memory storage devices, field effect resistance devices, antistatic films, biosensors, electrochromic devices, electrolyte capacitors, energy storage devices, touch panels and electromagnetic shielding.

15. The use according to claim 13, wherein the conductive layer is a solid electrolyte layer in a polymer electrolyte capacitor or hybrid electrolyte capacitor.

Description

[0226] The invention is now explained in more detail with the aid of non-limiting figures and examples.

[0227] FIG. 1 is a diagram of a section through a part of a capacitor obtainable by the process according to the invention for the production of a capacitor. This has an electrode body 1, usually made of a porous electrode material 2, such as aluminium or tantalum. On the surface 4 of the electrode material 2, a dielectric 3 is formed as a thin layer, so that an anode body 5 which is still porous and comprises the electrode body 1 of the electrode material 2 and the dielectric 3 is formed. The dielectric 3 is followed, optionally after further layers, by a layer of a solid electrolyte 6 (e.g., a layer that has been prepared using liquid composition 1 or 2 according to the present invention), whereby a capacitor body 7 comprising the electrode body 1 of the electrode material 2, the dielectric 3 and the solid electrolyte 6 is formed.

[0228] FIG. 2 is a TGA-diagram showing the weight-loss over temperature in the upper diagram for samples #1-#7. The lower diagram depicts the derivatives of weight vs. time scans.

[0229] FIG. 3 is a TGA-diagram showing the weight-loss over temperature in the upper diagram for samples #4, #8, #9 and #10. The lower diagram depicts the derivatives of weight vs. time scans.

[0230] FIG. 4 is a TGA-diagram showing the weight-loss over temperature in the upper diagram for samples #5, #11, #12 and #13. The lower diagram depicts the derivatives of weight vs. time scans.

TEST METHODS

Equivalent Series Resistance (ESR)

[0231] The equivalent series resistance (in m) was determined at 20 C. at 100 kHz by means of an LCR meter (Agilent 4284A). In each capacitor experiment at least 5 capacitors have been prepared and the average ESR-value was determined.

Thermal Stability

[0232] The thermal stability is determined by means of thermogravimetric analysis (TGA).

[0233] The TGA of solid samples is conducted with a TGA/DSC 2 LF/1100 from Mettler Toledo. About 10 g of the polymer dispersion of interest is dried at 100 C. for 16 h in a vacuum oven at 50 mbar in a beaker with a diameter of at least 3 cm to remove all solvents. About 15 mg of a solid conductive polymer is introduced into a measuring vial and the vial is placed in the support of the instrument.

[0234] The sample is first heated from room temperature to 100 C. The sample is kept then at 100 C. for 30 min under N.sub.2 to dry the sample. The sample is subsequently heated in a second heating scan without exposing the sample to air from 100 C. to 600 C. at a constant heating rate of 5 K/min. The weight of the sample is simultaneously monitored while heating.

[0235] The monitored weight loss of the sample over time is converted in a diagram of weight loss over temperature. The data are normalized to 100 wt. % at 100 C. Additionally, the derivative of the data is calculated, by forming the ratio of the differential change of mass in weight % and unit time.

Conductivity

[0236] A cleaned glass substrate was laid on a spin coater and 10 ml of the liquid composition according to the invention was distributed over the substrate. The remaining solution was then spun off by rotation of the plate. Thereafter, the substrate thus coated was dried for 15 minutes at 130 C. on a hot plate. The layer thickness was then determined by means of a layer thickness measuring device. (Tencor, Alphastep 500). The conductivity was determined in that Ag electrodes of 2.5 cm length were vapour deposited at a distance of 10 mm via a shadow mask. The surface resistance determined with an electrometer (Keithly 614) was multiplied by the layer thickness in order to obtain the specific electrical resistivity. The conductivity is the inverse of the specific electrical resistivity.

Average

[0237] If not otherwise mentioned, the average corresponds to the arithmetical average value.

EXAMPLES

Example 1 (Preparation of a PEDOT-S-Dispersion)

[0238] A 3L jacketed tank made of stainless steel is equipped a mechanical stirrer, a ventilation valve at the upper lid, a material inlet that can be closed and a thermometer.

Component A

[0239] Into this tank 2000 g of deionized water, 16.0 g of a 10 wt.-% aqueous iron (III) sulfate solution, 5.7 g sulfuric acid (95 wt.-%) and 100 g of EDOT-S sodium salt (0.29 mol) were introduced. The stirrer was operated at 50 rpm, the temperature was adjusted to 20 C. and the inner pressure was reduced to 100 hPa. The pressure in the tank was subsequently raised to atmospheric pressure, followed by a further reduction of a pressure to 25 hPa in order to expel the oxygen.

Component B

[0240] In a separate glass beaker 78.5 g sodium peroxodisulfate were dissolved in 200 ml water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0241] Component B was then sucked into the tank. The material inlet was then closed and the inner pressure of the tank was adjusted to 25 hPa by means of a vacuum pump. The initial pH of the reaction solution was 1.9 and the reaction was continued for 19 hours under this reduced pressure. After the reaction was completed, the reaction mixture was filled up to a volume of 10 L by adding deionized water and was subsequently treated by means of ultrafiltration (Pall Microza SLP 1053 with a cut-off of 10000 g/mol), whereby 8 L of water were removed. This procedure was repeated 6 times in order to remove the inorganic salts.

[0242] The thus obtained composition was characterized by a conductivity of 72 S/cm and a solid content of 1.22 wt. %. The composition was further concentrated by means of ultra-filtration until a solid content of 2.4 wt. % was reached. The thus obtained PEDOT-S-dispersion is subsequently referred to as sample #1)

Example 2 (Adjustment of pH-Value by Means of NaOH; Samples #2-#7, #21-#25)

[0243] A 100 ml beaker is filled with about 50 ml of sample #1. A 10 wt. % aqueous NaOH-solution is prepared and added dropwise to sample #1 while stirring until the solution has reached the desired pH. The pH of the solution is monitored with a pH-Meter (Model 766 Calimatic, Knick) while adding the base.

Example 3 (Adjustment of pH-Value by Means of LiOH; Sample #8)

[0244] Preparation as in Example 2 with the difference that a 10 wt. % aqueous LiOH-solution is added to adjust the pH.

Example 4 (Adjustment of pH-Value by Means of KOH; Samples #9 and #11)

[0245] Preparation as in Example 2 with the difference that a 10 wt. % aqueous KOH-solution is added to adjust the pH.

Example 5 (Adjustment of pH-Value by Means of NH.SUB.4.OH; Samples #10 and #12)

[0246] Preparation as in Example 2 with the difference that a 10 wt. % aqueous NH.sub.4OH-solution is added to adjust the pH.

Example 6 (Adjustment of pH-Value by Means of DMAH; Sample #13)

[0247] Preparation as in Example 2 with the difference that a 10 wt. % aqueous dimethylaminoethanol (DMAE)-solution is added to adjust the pH.

[0248] The TGA-diagrams of samples #1-#13 are outlined in FIG. 2, FIG. 3 and FIG. 4 depicting the weight-loss over temperature in the upper diagram each. The lower diagram depicts the derivatives of weight vs. time scans.

[0249] Table 1 displays in columns 5-8 the temperatures that correspond to a sample-weight of 100%, 90%, 80% and 70% as being extracted from the weight vs. temperaturedata in FIG. 2-4. The peak positions of the 1. peak at about 261 C. and 2. peak is at about 345 C. are extracted from the derivative-plots in FIG. 2-4 when assignable.

TABLE-US-00001 TABLE 1 sample weight [wt.-%] 100 90 80 70 T1.sup.1) DV1.sup.2) T2.sup.3) DV2.sup.4) ratio sample base pH temperature [ C.] [ C.] [1/min] [ C.] [1/min] DV1/DV2 Fig. 2 #1 1.8 100 242 265 306 261 0.51 341 0.37 1.378 #2 NaOH 2.1 100 269 321 341 261 0.22 341 0.55 0.400 #3 NaOH 2.5 100 311 337 350 261 0.087 344 0.88 0.099 #4 NaOH 3 100 329 344 358 n.d. 0.055 345 1.02 0.054 #5 NaOH 6 100 334 346 370 n.d. 0.03 345 1.14 0.026 #6 NaOH 8 100 334 345 383 n.d. 0.025 344 1.17 0.021 #7 NaOH 10 100 346 346 382 n.d. 0.025 344 1.13 0.022 Fig. 3 #4 NaOH 3 100 329 344 358 n.d. 0.055 345 1.02 0.054 #8 LiOH 3 100 322 341 360 n.d. 0.052 343 0.86 0.060 #9 KOH 3 100 330 344 353 n.d. 0.048 344 1.27 0.038 #10 NH.sub.3 3 100 275 303 334 261 2.000 334 0.40 5.000 Fig. 4 #5 NaOH 6 100 334 346 370 n.d. 0.03 345 1.14 0.026 #11 KOH 6 100 336 345 355 n.d. 0.027 348 1.47 0.018 #12 NH.sub.3 6 100 280 310 336 261 0.173 331 0.45 0.384 #13 DMAH 6 100 284 314 336 261 0.172 331 0.46 0.374 .sup.1)T1 = temperature at the 1.sup.st peak .sup.2)DV1 = derivative value at 261 C. .sup.3)T2 = temperature at the 2.sup.nd peak .sup.4)DV2 = derivative value of the 2.sup.nd peak

Example 7 (Preparation of a Capacitor)

[0250] Tantalum powder having a specific capacitance of 30000 CV/g was pressed to pellets with inclusion of a tantalum wire and sintered in order to form a porous anode body having dimensions of 1.4 mm2.8 mm3.9 mm. 5 of these porous electrode bodies were anodized in a phosphoric acid electrolyte at 60 V to form a dielectric, in order to obtain the anode bodies.

[0251] The anode bodies were impregnated in sample #3 for 1 min. Thereafter, drying was carried out at 120 C. for 10 min.

[0252] Next the anode bodies were impregnated in a PEDOT:PSS dispersion (Clevios K Nano LV, Heraeus) for 1 min. Thereafter, drying was carried out at 120 C. for 10 min. The impregnation and drying were carried out nine further times.

[0253] Next the anode bodies were dipped in a crosslinker solution (Clevios K Primer W5, Heraeus), dried at 120 C. for 10 min and thereafter dipped in a PEDOT:PSS dispersion (Clevios K V2 HV, Heraeus) and dried at 120 C. for 10 min. This sequential dip and dry in crosslinker and PEDOT:PSS dispersion was repeated additional two times.

[0254] Finally, the anode bodies were covered with a graphite layer and thereafter with a silver layer in order to obtain the finished capacitors in this way.

[0255] The mean values for ESR were determined before and after exposure of the capacitors to 125 C. for 100 hours. The relative increase in ESR is calculated as relative ESR increase=[ESR (after exposure to 125 C.)ESR (before exposure to 125 C.)]/ESR (before exposure to 125 C.). The value of the relative ESR increase in % is shown in Table 2.

Example 8

[0256] Capacitors were prepared the same way as in Example 7 except that sample #4 instead of sample #3 was used.

Example 9

[0257] Capacitors were prepared the same way as in Example 7 except that sample #5 instead of sample #3 was used.

Example 10

[0258] Capacitors were prepared the same way as in Example 7 except that sample #6 instead of sample #3 was used.

Example 11

[0259] Capacitors were prepared the same way as in Example 7 except that sample #8 instead of sample #3 was used.

Example 12

[0260] Capacitors were prepared the same way as in Example 7 except that sample #11 instead of sample #3 was used.

Example 13

[0261] Capacitors were prepared the same way as in Example 7 except that sample #12 instead of sample #4 was used.

Example 14

[0262] Capacitors were prepared the same way as in Example 7 except that sample #1 instead of sample #3 was used.

TABLE-US-00002 TABLE 2 relative ESR increase Example 7 (pH = 2.5; NaOH) 20% Example 8 (pH = 3; NaOH) 11% Example 9 (pH = 6; NaOH) 13% Example 10 (pH = 8; NaOH) 17% Example 11 (pH = 3; LiOH) 13% Example 12 (pH = 6; KOH) 11% Example 13 (pH = 6; NH.sub.3) 43% Example 14 (pH = 1.8) 89%