Preparation method for synthesizing and regulating PEDOT: PSS dispersion liquid by mixing different molecular weights of pair ions

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a preparation method for synthesizing and regulating PEDOT: PSS dispersion liquid by mixing different molecular weights of ions. The invention firstly provides a composition for improving the conductivity of a PEDOT: PSS dispersion liquid, and the composition comprises a 3, 4-ethylenedioxythiophene monomer and counter ion combinations with different molecular weights; the counter ions with different molecular weights are combined into poly (4-styrenesulfonic acid) and poly (4-styrenesulfonic acid) sodium with different molecular weights. The conductivity of the PEDOT: PSS dispersion liquid prepared by the method is obviously improved, a zeta potential result proves that the PEDOT: PSS dispersion liquid is stable in performance, and a subsequently prepared PEDOT: PSS film is high in light transmittance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a preparation method of a PEDOT:PSS dispersion liquid by synthesizing and regulating ions with mixed different molecular weights. Background Art

[0002] PEDOT has attracted wide attention due to its high conductivity (600 S / cm), good stability and excellent visible light transmittance. However, PEDOT itself is an insoluble polymer, so its application is limited to a certain extent. At present, the problem of PEDOT solubility can be solved by doping with water-soluble polymer electrolyte polystyrene sulfonic acid (PSS for short). Poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonic acid) (PEDOT:PSS) is a conductive polymer material in the form of a dark blue aqueous dispersion. Foreign companies are in the leading position in the production technology of PEDOT:PSS aqueous dispersion. Their product Clevios PH1000 has been widely used in various fields, such as solid electrolytic capacitors, antistatic coatings, through-hole circuit board electroplating (LED), etc. The price of PEDOT:PSS aqueous dispersion is very expensive in China. The price of Clevios PH1000 in China is as high as 8,000 yuan / L, while its laboratory production cost is about 300 yuan / L, and the price of industrial mass production is lower.

[0004] Many domestic researchers are also trying various strategies in the laboratory to improve the conductivity of PEDOT:PSS. The literature "Structural Regulation and Conductive Properties of PEDOT Conductive Polymers, Chemical Engineering, 2023" discloses that after post-treatment with sulfuric acid, the conductivity of PEDOT:PSS films shows a dependence on the molecular weight of PSS. As the molecular weight of PSS increases, its affinity for sulfuric acid molecules increases, and it is easier for sulfuric acid molecules to penetrate the PSS shell of PEDOT:PSS colloid particles to reach the core area enriched with PEDOT, thereby achieving a significant improvement in the conductivity of PEDOT:PSS films. However, this method relies on post-treatment with sulfuric acid, and the added sulfuric acid remains in the PEDOT:PSS dispersion system, which limits the application of PEDOT:PSS.

[0005] Therefore, it is necessary to propose new methods and strategies to supplement the deficiencies of existing technologies. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a PEDOT:PSS dispersion by mixing ions of different molecular weights to synthesize and regulate the dispersion, so as to partially solve or alleviate the above-mentioned deficiencies in the prior art. The present invention specifically adopts the following technical solutions.

[0007] One aspect of the present invention provides a composition for improving the conductivity of a PEDOT:PSS dispersion.

[0008] A composition for improving the conductivity of a PEDOT:PSS dispersion, the composition comprising a 3,4-ethylenedioxythiophene monomer and a counter ion combination of different molecular weights; the counter ion combination comprising at least two counter ions of different molecular weights; the counter ions of different molecular weights comprising poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonic acid) of different molecular weights; the molecular weight of the sodium poly(4-styrene sulfonic acid) being greater than the molecular weight of the poly(4-styrene sulfonic acid); and the weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination being 2:1-5.

[0009] Further, a weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination includes 2:1, 2:2, 2:3, 2:4 or 2:5.

[0010] Furthermore, the molecular weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) (PSSH:PSSNa) in the counter ion combination includes 70:80, 70:200, 70:500 or 70:1000.

[0011] Furthermore, the amount of the 3,4-ethylenedioxythiophene monomer used is less than the amount of the counter ion combination used.

[0012] As a preferred embodiment, the weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination is 2:5.

[0013] Furthermore, the weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination is 1-5:1.

[0014] Furthermore, the weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination includes 1:1, 2:1, 3:1, 4:1, and 5:1.

[0015] Furthermore, the amount of the poly(4-styrene sulfonic acid) used is greater than the amount of the sodium poly(4-styrene sulfonate) used.

[0016] As a preferred embodiment, the weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination is 4:1.

[0017] In some other optional embodiments, another composition for improving the conductivity of PEDOT:PSS dispersion can also be provided, the composition comprising three, four or five counterions of different molecular weights. Another aspect of the present invention provides a method for preparing PEDOT:PSS dispersion based on the above composition.

[0018] A method for preparing a PEDOT:PSS dispersion by mixing counter ions of different molecular weights comprises the following steps: S01: Add 3,4-ethylenedioxythiophene monomer and counter ion combination of different molecular weights to an appropriate amount of deionized water; the counter ion combination of different molecular weights is poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonic acid) of different molecular weights; the molecular weight of sodium poly(4-styrene sulfonic acid) is greater than the molecular weight of poly(4-styrene sulfonic acid); the weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination is 2:1-5; stir all the materials with a high-speed stirrer until they are in an emulsion state, and transfer them to a reaction kettle; S02: setting the reactor to an oxygen-free condition and a low temperature; the low temperature is less than 20° C.; S03: 0.001-0.5wt% of a catalyst, 0.5-1.5wt% of an oxidant and an appropriate amount of deionized water are uniformly stirred, and then slowly added dropwise into a reaction kettle to undergo a chemical oxidation polymerization reaction with the emulsion to obtain a first crude product of a PEDOT:PSS dispersion; S04: mixing the first crude PEDOT:PSS dispersion with an ion exchange resin in a ratio of 1:1, stirring and filtering to obtain a second crude PEDOT:PSS dispersion; S05: homogenizing the second crude PEDOT:PSS dispersion at a pressure of 100-250 bar to obtain the PEDOT:PSS dispersion.

[0019] Further, the molecular weight ratio of poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonate) in the counter ion combination includes 70:80, 70:200, 70:500 or 70:1000; or, the weight ratio of poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonate) in the counter ion combination is 1-5:1.

[0020] Furthermore, the ion exchange resin includes an anion exchange resin and a cation exchange resin; the ratio of the anion exchange resin to the cation exchange resin is 1:1.

[0021] As a preferred embodiment, the weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination is 2:5.

[0022] The catalyst includes ferric sulfate, ferrous sulfite, ferric chloride or ferrous chloride; or, the oxidant includes sodium sulfate, ammonium persulfate, sodium persulfate or potassium persulfate.

[0023] Beneficial technical effects: First, the present invention provides a method for synthesizing and regulating a PEDOT:PSS dispersion by mixing ions of different molecular weights. The conductivity of the PEDOT:PSS dispersion prepared by this method is significantly increased, and the maximum conductivity can reach 495±24 S / cm, and the minimum is not less than 380 S / cm. In addition, the zeta potential results of the PEDOT:PSS dispersion confirm that its performance is stable, and the subsequently prepared PEDOT:PSS film has high transmittance. Therefore, the PEDOT:PSS dispersion has more application scenarios.

[0024] Specifically, due to its good stability and high transmittance, the above-mentioned PEDOT:PSS film is suitable for preparing electrodes and circuits for flexible displays, which can realize the bending and folding functions of the display; its high conductivity and good film-forming properties enable the preparation of high-performance organic thin film transistor (OTFT) devices; high transmittance allows the light emitted by the organic light-emitting diode (OLED) to pass more effectively, thereby improving the light extraction efficiency and display effect of the device. Finally, the PEDOT:PSS is not doped with other impurity components, so it has better biocompatibility and can have broad application prospects in the field of biosensors. For example, it is used to prepare enzyme sensors, immunosensors, DNA sensors, etc., for detecting biological molecules, biological signals, etc. Furthermore, the present invention innovatively proposes a synthesis system strategy using mixed counterions of different molecular weights. In the system, at least two counterion combinations of different molecular weights are included (counterions with smaller molecular weights are used in larger amounts). This counterion combination of different molecular weights is polymerized with EDOT monomers. No other complex components or functional components are introduced in the entire preparation process. Only sufficient stirring at a relatively low room temperature is required. The preparation process is relatively simple, consumes less energy, and filtering and purifying the crude PEDOT:PSS dispersion is relatively easy. Therefore, this method has good industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without paying creative labor.

[0026] Figure 1 It is a schematic diagram of molecular synthesis of the preparation method of the present invention; Figure 2 The conductivity distribution diagram of PEDOT:PSS synthesized by mixing PSSH and PSSNa with different molecular weights; Figure 3 The zeta potential distribution diagram of PEDOT:PSS synthesized by mixing PSSH and PSSNa with different molecular weights; Figure 4 UV-Vis spectra of PEDOT:PSS films synthesized by mixing PSSH and PSSNa with different molecular weights; Figure 5 It is a process flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] Herein "and / or" includes any and all combinations of one or more of the associated listed items.

[0029] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0030] As used in this specification, the term "about" typically means + / -5% of the stated value, more typically + / -4% of the stated value, more typically + / -3% of the stated value, more typically + / -2% of the stated value, even more typically + / -1% of the stated value, and even more typically + / -0.5% of the stated value.

[0031] In this specification, some embodiments may be disclosed in a format of being in a range. It should be understood that this description of "being in a range" is only for convenience and brevity, and should not be interpreted as a rigid limitation on the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and independent numerical values ​​within this range. For example, the description of the range 1-6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within this range, such as 1, 2, 3, 4, 5 and 6. Regardless of the breadth of the range, the above rules apply.

[0032] Definition of noun: The "counter ion" mentioned in the present invention refers to an ion generated by poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonic acid) with a charge opposite to that on the main chain of PEDOT.

[0033] Example 1 This embodiment provides a specific example of a preparation method. It should be understood that this embodiment provides only an example and should not be construed as a limitation.

[0034] S01: Weigh 0.4 wt% EDOT, 0.8 wt% poly(4-styrene sulfonic acid) (PSSH) with a molecular weight of 70 kg / mol, 0.2 wt% poly(4-styrene sulfonic acid) sodium (PSSNa) with a molecular weight of 80 kg / mol, and 50 ml of deionized water, add them to the reaction vessel in sequence and stir evenly, emulsify with a high-speed stirrer for 30 minutes, and then add them to the reactor. In this embodiment, the weight ratio of PSSH to PSSNa is 4:1.

[0035] S02: Treat the reactor environment to an oxygen-free environment, such as a nitrogen environment.

[0036] S03: Weigh 0.9 wt% sodium persulfate, 0.1 wt% ferric sulfate and 20 ml deionized water, add them into the reaction container in sequence and stir evenly, set the reaction temperature to 16°C; then move to the reactor, set the reaction temperature of the reactor to 16°C, and perform polymerization reaction for 24 h to obtain the first crude PEDOT:PSS dispersion.

[0037] S05: After the reaction is completed, the first crude PEDOT:PSS dispersion: cation exchange resin: anion exchange resin are added to the anion and cation exchange resin in a ratio of 1:0.5:0.5, mixed and stirred for 8 hours, and filtered to obtain the second crude PEDOT:PSS dispersion.

[0038] S06: Use a high-pressure homogenizer to homogenize the second crude PEDOT:PSS dispersion at a pressure of 100-250 bar for 5 minutes to obtain a finished PEDOT:PSS dispersion (hereinafter referred to as PEDOT:PSS dispersion). The homogenization process will affect the particle size of the final product, and thus affect the performance of the final product. If the homogenization pressure is lower than 100 bar, the particle size of the obtained PEDOT:PSS dispersion is too coarse; if the homogenization pressure is higher than 250 bar, the particle size of the obtained PEDOT:PSS dispersion is too fine. The schematic diagram of the synthesis of the PEDOT:PSS molecule prepared in this example is shown in Figure 1 . Figure 1 In the figure, white balls represent H atoms, gray balls represent C atoms, red balls represent O atoms, and yellow balls represent S atoms.

[0039] The performance of the PEDOT:PSS dispersion synthesized in this example was verified.

[0040] Take 5 ml of PEDOT:PSS dispersion with a pipette, add 5% DMSO, stir evenly, and then use spin coating to evenly spin coat the PEDOT:PSS dispersion on the surface of the glass sheet, and then anneal on a 120℃ heating table for 10 minutes to obtain a dry PEDOT:PSS film. The conductivity of the PEDOT:PSS film is 495±24 S / cm, the zeta potential is -65 mV (Zeta potential below -30mv indicates very stable performance), and the transmittance is 93% in the visible light wavelength range of 400-600 nm.

[0041] Example 2 This embodiment provides a specific example of another preparation method.

[0042] S01: Weigh 0.4 wt% EDOT, 0.8 wt% poly(4-styrene sulfonic acid) with a molecular weight of 70 kg / mol, 0.2 wt% poly(4-styrene sulfonic acid) sodium with a molecular weight of 200 kg / mol, and 50 ml of deionized water, add them to the reaction vessel in sequence and stir evenly, emulsify with a high-speed stirrer for 30 minutes, and then add them to the reactor. The weight ratio of PSSH to PSSNa in this embodiment is 4:1.

[0043] S02-S06 are similar to Example 1. It is understood that the catalyst and oxidant used in the reaction are conventional amounts in the art, with the goal of achieving polymerization.

[0044] Example 3 This embodiment provides a specific example of another preparation method.

[0045] S01: Weigh 0.4 wt% EDOT, 0.8 wt% poly(4-styrene sulfonic acid) with a molecular weight of 70 kg / mol, 0.2 wt% sodium poly(4-styrene sulfonic acid) with a molecular weight of 500 kg / mol, and 50 ml of deionized water, add them to the reaction vessel in sequence and stir evenly. Emulsify with a high-speed stirrer for 30 minutes and then add them to the reactor.

[0046] S02-S06 are similar to Example 1. It is understood that the catalyst and oxidant used in the reaction are conventional amounts in the art, with the goal of achieving polymerization.

[0047] Example 4 This embodiment provides a specific example of another preparation method.

[0048] S01: Weigh 0.4 wt% EDOT, 0.8 wt% poly(4-styrene sulfonic acid) with a molecular weight of 70 kg / mol, 0.2 wt% sodium poly(4-styrene sulfonic acid) with a molecular weight of 1000 kg / mol, and 50 ml of deionized water, add them to the reaction vessel in sequence and stir evenly. Emulsify with a high-speed stirrer for 30 minutes and then add them to the reactor.

[0049] S02-S06 are similar to Example 1. It is understood that the catalyst and oxidant used in the reaction are conventional amounts in the art, with the goal of achieving polymerization.

[0050] Example 5 This example provides another specific example of a comparative preparation method.

[0051] S01: Weigh 0.4 wt% EDOT, 1 wt% poly(4-styrene sulfonic acid) with a molecular weight of 70 kg / mol, and 50 ml of deionized water, add them to the reaction vessel in sequence and stir evenly. Emulsify with a high-speed stirrer for 30 minutes and then add them to the reactor.

[0052] S02-S06 are the same as in Example 1.

[0053] Example 6 According to a method similar to Example 1, the PEDOT:PSS dispersions prepared in Examples 2 to 5 were prepared into dry PEDOT:PSS films, and their performance was tested. The results are shown in the following table.

[0054] Table 1 The experimental results are shown in Figure Figure 2-Figure 4 .

[0055] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0056] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A composition for improving the conductivity of a PEDOT:PSS dispersion, characterized in that: The composition comprises a 3,4-ethylenedioxythiophene monomer and a combination of counter ions with different molecular weights; the combination of counter ions comprises at least two counter ions with different molecular weights; the counter ions with different molecular weights comprise poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonic acid) with different molecular weights; the molecular weight of the sodium poly(4-styrene sulfonic acid) is greater than the molecular weight of the poly(4-styrene sulfonic acid); and the weight ratio of the 3,4-ethylenedioxythiophene monomer to the combination of counter ions is 2:1-5.

2. The composition according to claim 1, characterized in that The molecular weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination includes 70:80, 70:200, 70:500 or 70:1000.

3. The composition according to claim 1, characterized in that The weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination is 2:

5.

4. The composition according to claim 1, characterized in that The weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination is 1-5:

1.

5. The composition according to claim 4, characterized in that The weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination is 4:

1.

6. A method for preparing a PEDOT:PSS dispersion by mixing counterions of different molecular weights, characterized in that: The following steps are involved: S01: Add 3,4-ethylenedioxythiophene monomer and counter ion combination of different molecular weights to an appropriate amount of deionized water; the counter ion combination of different molecular weights is poly(4-styrene sulfonic acid) and sodium poly(4-styrene sulfonic acid) of different molecular weights; the molecular weight of sodium poly(4-styrene sulfonic acid) is greater than the molecular weight of poly(4-styrene sulfonic acid); the weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination is 2:1-5; stir all the materials with a high-speed stirrer until they are in an emulsion state, and transfer them to a reaction kettle; S02: setting the reactor to an oxygen-free condition; S03: 0.001-0.5wt% of a catalyst, 0.5-1.5wt% of an oxidant and an appropriate amount of deionized water are uniformly stirred, and then slowly added dropwise into a reaction kettle to react with the emulsion to undergo a chemical oxidation polymerization reaction, thereby obtaining a first crude product of a PEDOT:PSS dispersion; S04: mixing the first crude PEDOT:PSS dispersion with an ion exchange resin in a ratio of 1:1, stirring and filtering to obtain a second crude PEDOT:PSS dispersion; S05: homogenizing the second crude PEDOT:PSS dispersion at a pressure of 100-250 bar to obtain the PEDOT:PSS dispersion.

7. The preparation method according to claim 6, characterized in that: The molecular weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination includes 70:80, 70:200, 70:500 or 70:1000; or, the weight ratio of poly(4-styrene sulfonic acid) to sodium poly(4-styrene sulfonic acid) in the counter ion combination is 1-5:

1.

8. The preparation method according to claim 6, characterized in that: The ion exchange resin includes anion exchange resin and cation exchange resin; the ratio of the anion exchange resin to the cation exchange resin is 1:

1.

9. The preparation method according to claim 6, characterized in that: The weight ratio of the 3,4-ethylenedioxythiophene monomer to the counter ion combination is 2:

5.

10. The preparation method according to claim 6, characterized in that: The catalyst includes ferric sulfate, ferrous sulfite, ferric chloride or ferrous chloride; or, the oxidant includes sodium sulfate, ammonium persulfate, sodium persulfate or potassium persulfate.

Images