KR100648894B1 - Synthesis method of polyaniline by self dispersion polymerization method - Google Patents

Abstract

Provides a method for synthesizing polyaniline by stable dispersion polymerization and self-stabilized dispersion polymerization by using a reactant or an intermediate compound as a stabilizer without using other additives such as a stabilizer or an emulsifier. . The process was not only simple by performing the polymerization reaction without additional additives, but also greatly improved the electrical conductivity as well as the particle form of the synthesized polyaniline.

The polyaniline synthesized according to the present invention is not only used for requiring high conductivity such as electromagnetic shielding or thin film transparent electrode, but also due to improved solubility, various transparent electrodes, conductive films, fibers, polymer blends, battery electrodes, conductive etching masks, etc. It can be used suitably for special purposes such as.

Polyaniline, Self-Stabilized Dispersion Polymerization

Description

Process of Synthesizing Polyaniline by Self-Stabilized Dispersion Polymerization}

1 is a formula showing the theoretical repeating unit of the polyaniline in the emeraldine form, numbered carbon to explain the molecular structure of the polyaniline synthesized according to the present invention.

Figure 2 is a graph showing the spectra according to ¹³ C CPMAS NMR analysis of polyaniline synthesized according to a preferred embodiment of the present invention.

Figure 3 is a graph showing the spectra according to solution state 13C NMR analysis of polyaniline substituted with a tert-butoxycarbonyl (t-BOC) group to be soluble in accordance with a preferred embodiment of the present invention.

4 to 6 are scanning electron microscope (SEM) images of the polyaniline particles synthesized according to the preferred embodiment of the present invention, respectively, showing nanoparticles, nanotubes, and nanorod-shaped particle shapes.

7 is a graph showing the polyaniline particle size distribution synthesized according to the present invention.

The present invention relates to a conductive polymer, and more particularly, to a new conductive polymer polyaniline and a method for synthesizing the conductive polymer having a variety of particle shapes and greatly improved electrical conductivity.

The conductive polymer refers to a polymer having excellent conductivity characteristics compared to conventional organic materials by delocalizing electromagnetic through doping due to the conjugated structure present in the main chain. Since the first conductive polymer polyacetylene was developed by Shirakawa et al., Conductive polymers such as polyaniline, polypyrrole and polythiophene have been developed. .

These conductive polymers have anti-static materials of 10 ^-13 to 10 ^-7 S / cm, antistatic materials of 10 ^-6 to 10 ^-2 S / cm, and static discharge materials. S / cm or more is used for electromagnetic shielding materials or battery electrodes, semiconductors, solar cells, etc. If the conductivity value is improved, more various applications can be developed.

Among the conductive polymers, in particular, polyaniline is a polymer material that is of great interest in the related industry because it is relatively inexpensive and chemically stable compared to other conductive polymers, and is easily doped by hydrogen cations.

The polyaniline may be classified into leucoemeraldine which is a fully reduced form, ercoemeraldine which is a partially reduced form, emeraldine which is a partially oxidized form, and pernigraniline which is a fully oxidized form.

The method for synthesizing polyaniline can be broadly divided into electrochemical method by electrically charge transfer reaction and chemical oxidation method by protonation through redox reaction or acid / base reaction. Chemical oxidation methods are known to be suitable for mass production on an industrial scale.

As a method for synthesizing representative polyaniline by chemical oxidation method, a method reported by McDiamide et al. Is known as a standard method (AG MacDiarmid, JC Chaing, AF Richter, NLD Somarisi, in L. Alcacer (ed.), Conducting) Polymers, Special Applications, Reidel, Dordrecht, 1987, p. 105). McDiamide et al. Polymerized aniline monomer dissolved in hydrochloric acid at 1-5 ° C. using an oxidizing agent such as ammonium persulfate in aqueous solution, and then precipitates were separated and washed to synthesize polyaniline. Only low molecular weight (high viscosity 0.8-1.2 dl / g) of polyaniline in the form of Emeraldine Base (EB) prepared according to this method is dissolved in 1-methyl-2-pyrrolidone (NMP), Emeraldine salt (ES.CSA) doped with camphorsulfonic acid (CSA) is dissolved in small amounts in metacresol. The electrical conductivity of the film prepared from this solution is about 100 S / cm, but the emuldine salt (ES.HCl) doped with hydrochloric acid shows an electrical conductivity of about 5 S / cm. In particular, the method such as McDiamide has to separate the insoluble portion, there is a limit to control the morphology of the synthesized polyaniline, increase the molecular weight or increase the electrical conductivity.

Various preparation methods using emulsion polymerization have been disclosed in order to improve the problems caused by methods such as McDiamide and to improve the processability of polyaniline. For example, Sao et al. (Cao et al., US Pat. No. 5,231,631, 5,324,453) dissolve aniline units, functional hydrogen acids, etc. in polar solvents such as water and mix them with non-polar organic solvents to produce emulsions. , An oxidizing agent was added to the emulsion to prepare a polyaniline. In this way the produced salt raldin Emma (ES) are known to be an emulsifier to form a complex with polyaniline by performing a dopant (dopant) station soluble in a non-polar organic solvent such as xylene. However, doping control using a functional organic acid that functions as an emulsifier is difficult and is generally expensive, and it is difficult to separate the polyaniline after synthesis, thereby limiting its use and having poor electrical properties. For example, dodecylbenzene sulfonate (DBS) has a solubility of less than 0.5% and a conductivity of only 0.1 S / cm.

Kinlen (US Pat. No. 5,567,356; Macromolecules, 31, 1745 (1998)), a Monsanto researcher, is an organic solvent, such as 2-butoxyethanol, which is soluble in water and is insoluble in water, After making a reverse emulsion with an organic acid that is an emulsifier, the aniline unit and the radical initiator are mixed and polymerized to separate an organic layer including a polyaniline salt and an aqueous layer containing a radical initiator or an unreacted substance, and thus, at least 1% in a nonpolar solvent. Dissolved polyaniline salts were prepared. This method is not easy to polymerize because the radical initiator layer and the monomer layer are separated, and the electrical conductivity of the synthesized polyaniline is also low because of difficult doping control. For example, the conductivity of polyaniline salts synthesized using a hydrophobic organic acid, dinonylnaphthalenesulfonic acid, has been reported to be about 10 ^-5 S / cm when measured from pellets.

Palaniappan et al. (US Patent Application Publication No. 2002-0062005, US Patent No. 6,586,565 and US Patent No. 6,630,567) comprise a radical initiator such as benzoylperoxide dissolved in an organic layer after being composed of an aqueous layer and an organic layer using a surfactant. Discloses a process for preparing polyaniline salts through inverted emulsion polymerization at room temperature. The electrical conductivity of the polyaniline film prepared according to this method is low at the level of 0.1 S / cm, and the use of the polyaniline is not limited because the molecular weight of the polyaniline cannot be increased.

Unlike the emulsion polymerization as described above, the unit such as aniline is completely dissolved in the reaction solvent, but many methods have been reported in connection with the production of polyaniline using dispersion polymerization in which the resulting polymer is not dissolved under the same conditions. For example, Armes et al. (Armes et al., Handbook of Conducting Polymers Elsenbaumer ed. M. Dekker, New York, 1996 Vol. 1, p 423) design special stabilizers to stabilize particles in three dimensions and then granulate them. The polymerization method is reported. In this dispersion polymerization method, almost all of the polyaniline produced using the stabilizer surrounds the polyaniline, so that it can be supplied in an aqueous solution.However, the particle size of the synthesized polyaniline is 60-300 nm and is not affected by the stabilizer. Its use is limited because its electrical conductivity is low.

On the other hand, a method for synthesizing polyaniline in an aqueous solution containing an organic solvent has also been reported. Geng et al. (Geng et al., Synth. Metals, 96, 1 (1998)) polymerize aniline using organic solvents such as ethanol, THF, acetone and the like to produce polyaniline having a conductivity of about 10 S / cm. It was. However, in the method of Geng et al., Since the reaction time is prolonged, the possibility of side reactions during polymerization increases.

The study of Beadel et al. (Beadle et al., Synth.Mt. 95, 29 (1998)) showed that electrical conductivity increases with increasing molecular weight for polyaniline prepared by a kind of standardized synthesis presented by McDiamide et al. If the polymerization takes place in a homogeneous aqueous solution to lower the reaction temperature, metal salts such as LiCl and CaF ₂ are usually added to prevent freezing. When the reaction time is completed, the reaction completion time is longer than 48 hours, and the reaction control is difficult, and when the reaction temperature is lowered, the molecular weight distribution increases with the molecular weight (dispersity of 2.5 or more).

In addition, since aniline units are added to the quinonediimine group in the middle of the chain, a branch is formed.In order to suppress the formation of such branches, FeCl ₃ is added as an oxidant in the middle of the reaction, or an oligomer in which the synthesis reaction is stopped during the polymerization reaction. In some cases, organic solvents may be used to remove by-products. In addition, in the above-mentioned emulsion polymerization or interfacial polymerization, since the addition reaction is likely to occur not only in the para position of the benzene ring included in the polyaniline backbone but also in the ortho position, a large number of side branches are inevitably generated. This causes a drop in conductivity and solubility.

Huang et al. (Huang et al., J. Am. Chem. Soc. 125, 314 (2003)) also established that the organic layer and the aqueous solution layer do not mix with each other, and then the aniline unit is added to the organic layer and the initiator and organic acid The polyaniline in the form of nanofibers was prepared by dissolution and polymerization at the interface. In a subsequent study, Huang et al. (Huang et al., Angew. Chem. Int. Ed. 43, p5817, 2003) contributed to increasing the yield of nanofibers by performing interfacial polymerization using organic solvents. Rather it is reported that nanofibers can be prepared by rapid mixing in aqueous solution.

On the other hand, Min (G. Min, Synt. Met., 119.273 (2001)), a researcher at Dupont Technology in the United States, increased the concentration of LiCl or NaCl as an additive in the above-described McDiamide method (5-10 M). It has been reported that a high yield polymer can be obtained by polymerization at 3 ° C. for 3 hours.

However, as described above, the polyaniline manufacturing method disclosed to date is difficult to obtain pure polyaniline because a substituent is introduced into the unit or a large amount of additives such as stabilizers and emulsifiers are used, and the microstructure is also difficult to obtain chains at ortho positions. The electrical conductivity of the polyaniline produced is not high because the rate of connection is high and the side branches are frequently attached by side reactions or the like.

Conductive polymers, by themselves, do not form perfectly linear forms, so they cannot form an order like crystal form, so the actual conductivity is approximately 10 ^5-6 S / cm (Kohlman et al., Phys. Rev. Lett. 78 (20), 3915, 1997). Since the polymer having low electrical conductivity is not suitable for plastic transparent electrodes or electromagnetic wave shielding, it is necessary to design a conductive polymer having excellent electrical conductivity and solubility and an easy polymerization reaction.

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a conductive polymer polyaniline and a method for synthesizing a variety of particle shape and greatly improved electrical conductivity.

Self-Stabilized Dispersion Polymerization used in the present invention is a new polymerization method for stably dispersing the synthesized polymer particles without using any other additives such as emulsifiers and antifreeze agents.

Accordingly, another object of the present invention is to dramatically reduce the polymerization time to greatly improve the economics and efficiency, and to provide a polyaniline having an improved particle form of nanoparticles, nanotubes, nanorods, nanofibers, and the like, and a method for synthesizing the same. There is.

Other objects and advantages of the present invention will become more apparent from the following drawings and the configuration of the invention.

The present invention is to solve the above problems, in one aspect of the present invention is to prepare a mixed solution by mixing an organic solvent in the aqueous hydrochloric acid solution containing the aniline unit and the initiator, the temperature of -45 ~ -10 ℃ Provided is a method for synthesizing polyaniline through polymerization of aniline units in a heterogeneous system.

In this case, the aniline unit is a monomer represented by the following formula (I).

In particular, the above said polyaniline synthesized in accordance with the present invention is ¹³ C CPMAS NMR has a single peak at a chemical shift 123 ppm or chemical shift 158 ppm in the spectrum, ¹³ C CPMAS in NMR spectra chemical shift 138 ppm and at the chemical shift 143 ppm Each has a verifiable peak.

In this case, the polyaniline is characterized in that the peak intensity at 138 ppm chemical shift in the ¹³ C CPMAS NMR spectrum is greater than the peak intensity at 143 ppm chemical shift.

The hydrogen acid used according to the present invention is characterized in that the inorganic acid selected from hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid, the organic solvent is characterized in that the solubility factor is 17 ~ 29.

Organic solvents that may be used in connection with the present invention include hydrocarbons, unsubstituted or substituted with halogen, carboxyl groups, oxygen or hydroxy groups, ethers, unsubstituted or substituted with halogen, nitrobenzene, or mixtures thereof, in particular bis ( 2-chloroethyl) ether, 3-pentanol, 1,2-propanediol, butyl methyl ketone, diethyl carbonate, benzyl acetate, dimethyl glutarate, ethyl acetoacetate, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, Ethylene glycol monobutyl ether, isobutyl isobutanoate, isobutyl acetate, 3-heptanol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, meta-cresol, 4- Hydroxy-4-methyl-2-pentanone.

Meanwhile, the initiator which can be used in the present invention includes ammonium peroxide, hydrogen peroxide, manganese oxide, potassium dichromate, potassium iodide, ferric chloride, potassium permanganate, potassium bromide, or potassium chlorate.

In addition, the polyaniline synthesized according to the present invention has a pore form such as foam, honeycomb or hollow capsule composed of nanoparticles, in particular nanotubes, nanofibers.

On the other hand, according to another aspect of the invention, the polyaniline synthesized according to the above-described method, it characterized in that it has an electrical conductivity of 300 S / cm or more.

In this case, the polyaniline preferably has an electrical conductivity of 500 S / cm or more, for example, 700 S / cm or more or 900 S / cm or more, more preferably 1100 S / cm or more, and most preferably 1300 S. It may have a conductivity of more than / cm.

In the present invention, as described above, a novel method for synthesizing polyaniline without the use of any additives other than aniline monomers, hydrogen acids, organic solvents, and initiators, such as emulsifiers and antifreezes, which are necessary in the polyaniline polymerization step Developed.

The reaction system used in the present invention forms a dispersion system that is itself stabilized by the reactants used, unless otherwise stated herein, often referred to as "self-dispersion polymerization method" for polyaniline synthesis methods used according to the present invention. Self-Stabilized Dispersion Polymerization ("SSDP") is used.

In addition, the high conductivity polyaniline of the nanoparticles synthesized using the SSDP process according to the present invention is referred to herein as "HCPANI" unless stated otherwise, and often referred to as "PANI" for polyaniline synthesized according to the conventional method. do. At this time, HCPANI described in the present specification is a polyaniline synthesized by the SSDP process from the aniline monomer represented by the following formula (I), leucomeraldine, emeraldine base (EB) is called according to the degree of oxidation , An emeraldine salt (ES), or furnig aniline is used as a term referring to any or all thereof.

Meanwhile, according to one embodiment of the present invention, a polyaniline substituted with a tert-butoxycarbonyl (t-BOC) group in HCPANI synthesized by the SSDP process presented in, is referred to as "HCPANI-tBOC".

In addition, the HCPANI obtained through the SSDP process of the present invention shows the shape of the nanoparticles in the form of nanorods, nanofibers, and nanotubes. Nanoparticles according to the present invention is a concept including not only nanoparticles in the exact sense having a size of 1 nm to 100 nm, but also particles having a diameter in the range of 1 nm to several tens of micrometers. That is, the term 'nano particles' as used herein refers to the aggregated form of chains of HCPANI synthesized according to the present invention, which means that it includes all nanorods, nanotubes, nanofibers according to the form.

In the method for synthesizing polyaniline adopted in the present invention, the reactant containing the aniline unit represented by the formula (I) is mixed in a reaction system composed of two phases, an aqueous phase and an organic solution phase. Since the reactants and products play a role in stabilizing the reaction system, conventional emulsion polymerization using standardized polymerization methods such as McDiamide and emulsifiers, polymer stabilizers, low molecular stabilizers or other templates in principle. They are essentially distinguished from suspension polymerization or dispersion polymerization. According to the present invention, the two phases constituting the reaction system may be a discontinuous phase if the aqueous phase is a continuous phase, and the aqueous phase may be a discontinuous phase if the organic phase is a continuous phase, and both phases may be a continuous phase.

The aqueous phase constituting the reaction system according to the present invention includes a hydrophilic solvent containing water, an aniline unit represented by the formula (I), a hydrogen acid and an organic solvent at the time of the reaction.

As the hydrophilic solvent, water, methyl alcohol, ethyl alcohol, acetonitrile, 2-methoxyethanol and mixed solvents thereof may be used, but water is preferably used alone.

The hydrogen acid is an inorganic or organic acid having pKa 4 or less, more preferably pKa 3.5 or less, and more specifically, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or alkyl sulfonic acids such as methylsulfonic acid, and dodecylbenzenesulfonic acid. Organic acids such as arylsulfonic acid or chlorosulfonic acid, halogenated alkyl sulfonic acids such as trifluorosulfonic acid, or mixtures thereof. Preferably, an inorganic acid such as hydrochloric acid can be used.

The organic solution phase constituting the reaction system according to the present invention preferably comprises an organic solvent which is not mixed with the aqueous phase or may be mixed in small amounts. When selecting an organic solvent that can be used in the synthesis of a polymer, such as the present invention, reference is made to a solubility parameter which is closely related to the g molecular weight, density, etc. of the polymer. As the constituent organic solvent, an organic solvent having a solubility factor in the range of 19 to 29 may be used. Depending on the nature of the organic solvent, reactivity, yield, particle shape, conductivity, etc. are affected, but there are few essential differences.

The organic solvent contained on the organic solution according to the present invention includes an unsubstituted or substituted hydrocarbon with a halogen, a hydroxy group, a carboxyl group, a ketone group, oxygen, or the like, or an organic solvent that can be used in a conventional polymerization reaction. do. The hydrocarbon may be, for example, an alkyl halide as a halogen substituted hydrocarbon, an ether substituted with halogen, or an aromatic hydrocarbon substituted with halogen. Hydrocarbons substituted with hydroxy groups include alcohols having 3 to 15 carbon atoms.

Specifically, the halogen-substituted hydrocarbons that can be used in the present invention include: i) dichloromethane, pentachloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane Alkyl halides such as trichloroethane, ethyl chloride, 1,2,3-trichloropropane, dichloropropane, ii) bis (2-chloroethyl) ether, ethers such as dichloroethyl ether, i) 1,2-dichloro Aromatic hydrocarbons such as benzene.

Meanwhile, alcohols having 3 to 15 carbon atoms as examples of hydrocarbons substituted with hydroxy groups according to the present invention include 1-propanol, 2-methyl-2-propanol, 1,2-propanediol, 1,3-propanediol, Butanol, neopentanol, 2-ethyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 1,5-pentanediol, amyl alcohol, 2- Pentanol, 3-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, 4-methyl-2- Pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, isobutanol, 3-heptanol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol , 1-octanol, 2-octanol, triethylene glycol, 2-methoxyethanol, 2-butoxyethanol, ethylhexanol, cyclohexanol, decanol, dodecanol, diethylene glycol, tetraethylene glycol, tetra Hydrofurfuryl alcohol.

Meanwhile, examples of the hydrocarbon substituted with oxygen according to the present invention include ethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene. Glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, and ethylene glycol monobutyl ether.

In addition, ketones that can be used according to the present invention include cyclopentanone, cyclohexanone, diacetone alcohol, butyl methyl ketone, 4-methyl-2-pentanone, and 4-methyl-2-pentanone. Methyl ethyl ketone, 4-hydroxy-4-methyl-2-pentanone.

On the other hand, the organic solvent that can be used in the present invention is diethylcarbonate (diethylcarbonate), benzyl acetate (benzyl acetate), dimethyl glutarate (dimethyl glutarate), ethyl acetoacetate (ehtylacetoacetate), isobutyl isobutanoate (isobutyl isobutanoate, isobutyl acetate, and meta-cresol.

In addition, as a conventional organic solvent used for synthesizing polyaniline, an organic solvent such as toluene, xylene, nitrobenzene can also be used in the present invention.

Meanwhile, as the radical initiator added to the aqueous solution in connection with the present invention, ammonium peroxisulfate, hydrogen peroxide, manganese dioxide, potassium dichromate, potassium iodate, and potassium chloride Ferric chloride, potassium permanganate, potassium bromate, potassium chlorate or mixtures thereof. Preferably ammonium persulfate. As such, when ammonium persulfate is used in the oxidizing agent used as the radical initiator, two electrons per molecule are involved, so the amount of the radical initiator is 0.1 to 2 molar equivalents, preferably 0.1 to 0.75 molar equivalents, most per mole of the monomer. Preferably it is used in 0.1-0.5 molar equivalent.

 Since the polymerization reaction according to the present invention is exothermic, it is preferable to stir well during the reaction, and the reaction temperature can be from -45 to -10 ° C. Since the reaction time and the molecular weight of the produced polymer are sensitive to the reaction temperature, it is preferable to select a suitable temperature from the above temperature range and keep it constant according to the desired molecular weight, the molecular weight distribution of the produced compound, and the electrical conductivity level.

Once the reactants described above according to the invention are placed in a reactor to initiate the reaction and the polymerization reaction is complete, the polymer can be separated in various ways depending on the desired form of the final product. For example, when the synthesized HCPANI is washed with water or methyl alcohol, and then recovered, conductive emeraldine salts (ES) having various shapes can be obtained, and when treated again with a base, an emeraldine base (EB) which is well dissolved in an organic solvent can be obtained. It is obtained in the form of) and can be used for various purposes by re-doping it by doping or re-doping after forming. It is also possible to easily prepare the obtained EB in the form of leucomeraldine, furniger aniline and the like through an oxidation-reduction reaction.

An advantage of the synthesis / manufacturing process of the conductive polymer according to the present invention is that molecular weight control is easy. By varying the reaction conditions according to the present invention, a polymer material having a molecular weight of 10,000 to 385,000 can be obtained. The polymer material produced according to a preferred embodiment is dissolved in sulfuric acid at a concentration of 0.1 g / dl and measured at about 30 ° C. The intrinsic viscosity value of was 0.1-2.9. In particular, the polymer material synthesized according to the present invention not only has a large structural difference compared to the polyaniline synthesized according to the conventional method, but also shows a large difference in electric conductivity values when doped.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a formula showing the theoretical repeating unit of the polyaniline in the emeraldine form, the numbering of carbon to explain the molecular structure of the polyaniline synthesized according to the present invention, Figure 2 is a preferred embodiment of the present invention It is a graph showing the spectrum according to ¹³ C CPMAS NMR analysis of the polyaniline synthesized according to.

As shown in FIG. 2, HCPANI synthesized according to one embodiment of the present invention has two peaks clearly distinguished around about 140 ppm of chemical shift in the ¹³ C CPMAS NMR spectrum, that is, a peak at about 138 ppm of chemical shift ( I ₁₃₈ ) and chemical shift peak (I ₁₄₃ ) at about 143 ppm.

According to Raghunathan et al, the peaks formed around about 140 ppm of chemical shifts in the ¹³ C CPMAS NMR spectrum of polyaniline are due to protonated carbon linked to the oxygen of the quinoid ring in the repeating units of polyaniline shown in FIG. (Raghunathat et al., Synth.Met. 81, 39-47, 1996; Yasuda et al., Synth.Met. 61, 239-245, 1993).

In particular, it was also confirmed that the HCPANI of the present invention synthesized through the SSDP process has a peak intensity at about 138 ppm of chemical shift in the ¹³ C CPMAS NMR spectrum greater than a peak intensity at about 143 ppm of chemical shift. This relationship between peak intensities around 140 ppm is one of the features of HCPANI synthesized according to the present invention.

In the repeating unit of the polyaniline of the emeraldine type shown in Figure 1, the quinoid ring (quinonediimine repeating unit) is connected to the imine bond and can not be rotated, and the "-N =" bond of the curved form is not straight. Have. Therefore, in an ideal polyaniline structure, four carbon atoms (C4) on the quinoid ring in the repeating unit of FIG. 1 lose the uniformity. It was confirmed that the EB-formed HCPANI synthesized in the present invention shows the peak form and peak intensity that can be derived from the theoretical structure. Therefore, the HCPANI synthesized in the present invention can be inferred to be close to the theoretical structure. have.

Wei et al. Have reported that the aniline monomer is linked to the quinoid ring of the polyaniline of the EB form by the Michael addition reaction to form a structure as follows. However, the peak shape of HCPANI synthesized in the present invention around 140 ppm of chemical shift in ¹³ C CPMAS NMR spectrum is interpreted to maintain linearity with little addition reaction.

Meanwhile, it was confirmed that HCPANI synthesized by the SSDP process of the present invention had a single peak at about 123 ppm of chemical shift and about 158 ppm of chemical shift in ¹³ C CPMAS NMR spectrum.

^A single peak formed around 123 ppm of the chemical shift according to ¹³ C CPMAS NMR analysis is formed on the carbon atoms C1 and C2 of the benzenoid ring (phenylenediamine repeat structure), which may have some internal rotation, among the polyaniline repeat units of the EB form of FIG. Corresponds. That is, it was confirmed that HCPANI synthesized according to the present invention has an equivalent carbon atom in the benzenoid ring in the repeating unit.

On the other hand, in the ¹³ C CPMAS NMR spectrum of the polyaniline, the peak formed at about 158 ppm of chemical shift is derived from the carbon C8 of the quinoid ring in the repeating unit of the polyaniline of the EB form shown in FIG. However, since HCPANI synthesized according to the present invention has a single peak at 158 ppm of chemical shift in ¹³ C CPMAS NMR spectrum, it can be seen that the HCPANI of the present invention is also uniform in the quinoid ring.

As a result, HCPANI synthesized according to the present invention has almost no bonds to the carbons connected to the quinoid ring and the benzenoid ring in the repeating unit of the polyaniline of the EB form, and thus the aniline monomer is connected only by para-coupling to improve linearity. According to the present invention, it was found to have much higher conductivity and solubility than the conventional one.

Improvement of the chemical microstructure of HCPANI synthesized according to the SSDP process of the present invention was further confirmed through solution state ¹³ C NMR analysis of the EB-type HCPANI synthesized according to the present invention. Figure 3 shows the spectral results obtained by solution ¹³ C NMR analysis in the state substituted HCPANI synthesized according to an embodiment of the present invention with t-BOC. As shown, HCPANI synthesized according to the present invention showed little ambient peak in solution state ¹³ C NMR analysis. Second, the HCPANI synthesized according to the present invention had only four main peaks of quaternary C ¹³ which caused resonance between about 139.5 ppm and about 160 ppm of chemical shift in solution ¹³ C CPMAS NMR spectrum.

In general, peaks visible between 139.5 ppm and about 160 ppm of chemical shifts in solution state ¹³ C NMR spectra are known to originate from polyaniline linked to para positions. As mentioned above, the fact that the HCPANI synthesized according to the present invention has four main peaks clearly distinguished in this range is that the HCPANI synthesized according to the present invention is almost in the para position compared to the PANI synthesized by the conventional method. As a result, the linearity is greatly improved.

In addition, HCPANI synthesized according to the present invention does not show a peak of C ¹³ which causes resonance between the chemical shift of 110 ppm or less and the chemical shift of 130 ppm to 135 ppm in the solution state ¹³ C NMR spectrum. It is known that peaks between 110 ppm and 135 ppm of chemical shifts in the solution state ¹³ C NMR spectrum of polyaniline, or between 130 ppm and 135 ppm of chemical shifts, are associated with polyaniline linked or other branched at the meta position. HCPANI of the present invention was confirmed that the polymer has almost no side branches.

On the other hand, HCPANI synthesized according to the present invention showed little peaks at about 149 ppm and 152 ppm of chemical shifts, which are known to be closely related to polyaniline branching side reactions in solution ¹³ C NMR spectrum.

In particular, HCPANI synthesized according to the present invention was determined to have up to 10 chemical shifts between about 117 ppm and about 139 ppm in solution ¹³ C NMR spectrum. Peaks between about 117 ppm and about 139 ppm of chemical shifts in solution state ¹³ C NMR spectra for polyaniline are directly bonded to hydrogen in the benzenoid ring and quinoid ring of the repeating unit Corresponds to C3. However, the smallest number of peaks observed within this range means that the polyaniline synthesized according to the present invention is greatly improved in uniformity.

In addition, the HCPANI synthesized according to the present invention has a relatively small peak intensity in the range of 123 ppm to 124 ppm of chemical shift in solution ¹³ C NMR spectrum. That is, in the case of HCPANI synthesized according to the present invention, the peak formed between 123 ppm and 124 ppm of the chemical shift was found to have an intensity of about 1/5 or less due to its strong drop compared to the peak formed near 125 ppm of the chemical shift. .

In addition, HCPANI synthesized according to the present invention has two peaks present between about 136 ppm and 138 ppm of chemical shifts in the solution state ¹³ C NMR spectrum, with a surrounding peak present within 1 ppm distance from the center of each of these peaks. In contrast to few, conventional PANI can see that there are many peaks in the range.

As a result, the HCPANI synthesized according to the present invention was compared with the conventional PANI was mainly found in the connection of the aniline monomers in the para position, it was found that the side reactions or side-branch reaction hardly occurs.

On the other hand, in addition to the difference in the chemical microstructure of the present invention, it was confirmed that the HCPANI synthesized according to the present invention has unique characteristics in its physical structure. In the present invention, it was confirmed that the polymer is composed of an aqueous solution phase and an organic solution phase, but because the polymerization reaction is performed in a reaction system that stabilizes itself, the shape of the synthesized polymer is unique.

4 to 6 are scanning electron microscope (SEM) images of the polyaniline particles synthesized according to the preferred embodiment of the present invention, respectively, showing nanoparticles, nanotubes, and nanorod-shaped particle shapes. As shown, the cross-section of the HCPANI particles synthesized according to the present invention is approximately 10 nm to 50 μm in length, especially in the case of tubular particles, the length of which is longer and more varied, all in the form of foam or honey comb. It has a pillar or rod shape with pores formed inside.

Specifically, in the case of HCPANI synthesized according to an embodiment of the present invention, globular nanoparticles having a size of about 20 to 80 to 20 to 80 nm are gathered to form a network structure (FIG. 4), or hollow nanoparticles. The rods of size have the shape of a tube (FIG. 5), or are shaped like nanofibers (FIG. 6).

Due to such a structure, the surface area of HCPANI synthesized according to the present invention is greatly increased, so that the solubility in organic solvents can be greatly increased. In this regard, when the number average molecular weight of HCPANI in the form of conductive EB synthesized according to one embodiment of the present invention is 15,000, the solubility is about 10% by weight / NMP at room temperature, and the solubility of polyaniline in the form of EB is 5% by weight / It is about twice as high as NMP, and especially when the number average molecular weight is 15,000-80,000 (intrinsic viscosity: 1.7-2.7 dl / g), the solubility of 3 wt% / NMP or more is higher than that of conventional polyaniline of 2 wt% or less. Is showing.

On the other hand, HCPANI synthesized through the SSDP process of the present invention was confirmed that the molecular weight distribution is significantly improved compared to the conventional. Figure 7 is a graph showing the polyaniline particle size distribution synthesized according to the present invention, it can be seen that the molecular weight of HCPANI synthesized by the present invention is concentrated in the center.

In addition, it was confirmed that the molecular weight and the electrical conductivity of the polymer synthesized according to the present invention has a close correlation. When the number average molecular weight of PANi synthesized according to the preferred embodiment of the present invention is in the range of 10,000-12,000, the conductivity is about 100-300 S / cm, while the conductivity is 300 when the number average molecular weight is increased to 13,000-89,000. It tends to increase to -1300 S / cm.

As described above, the improved chemical microstructure, physical structure, dispersion degree, etc. of HCPANI synthesized according to the present invention is a dispersion system in which the material synthesized by the self-dispersion polymerization method of the present invention is dispersed in a stable particle form from the initial reaction to the end of the reaction. It is interpreted that it is because it forms.

Hereinafter, the present invention will be described in more detail through illustrative examples. However, the following examples are only for describing the present invention in detail, and the present invention is not limited thereto.

Example

<Electric conductivity measurement>

Electrical conductivity was measured at a relative humidity of 50% at room temperature by a conventional four line probe method. Carbon paste is used to prevent corrosion at the contact of gold wire electrode, and current ( i ), voltage (from the thickness t , width w ) are generally 0.1 ~ 100 ㎛ thick. v ), the distance ( l ) between two outer electrodes and two inner electrodes was measured, and the conductivity thereof was measured using a Keithley conductivity measuring device. The conductivity was calculated using the following equation, and the unit of conductivity was Siemen / cm or S / cm.

Electrical conductivity = ( l · i ) / ( w · t · v )

In order to confirm the uniformity of the conductivity of the specimen, it was measured by Van der Pauw method, which is a standard four point probe, and the result was consistent within 5%.

<Particle size measurement>

Particle size analyzer Mastersizer Micro was used. Some samples were taken in the middle of the reaction and particle size distribution was measured by light scattering.

<SEM particle shape measurement>

SEM (Scanning Electron Microscope) was used to observe the particle shape using Model XL-30, Philips Co. Since the image observation covers only a very limited area, a large number of photographs were observed to obtain representative shapes.

<NMR analysis>

¹³ C CPMAS nuclear magnetic resonance spectra were obtained from Bruker NMR instrument at 100.6 MHz, spinning rate 7 KHz, and tetramethyl silane (TMS) was used as standard. Solution state ¹³ C NMR spectra were obtained in a conventional manner after dissolving the sample in CDCl ₃ using a JEOL Lambda 400 instrument.

Example 1

In this example, HCPANI in the form of an emeraldine salt was synthesized according to a self-dispersion polymerization method. First, 100 mL of distilled and purified aniline was slowly added dropwise to 6 L of 1 M HCl solution, and then 4 L of ethylene glycol dimethyl ether was mixed into the above solution. The temperature of the mixed solution was fixed at −10 ° C., and 56 g of ammonium peroxide sulfate ((NH ₄ ) ₂ S ₂ O ₈ ) dissolved in 2 L of 1M HCl solution was slowly stirred well for 40 minutes in the mixed solution. I added dropwise. After maintaining the stirring speed at 100 rpm / min for 4 hours, the reaction was completed and the obtained precipitate was filtered through a filter paper, and polyaniline in the form of a salt was recovered, and a part thereof was washed with 1 L of 1M ammonium hydroxide (NH ₄ OH) solution. The precipitate was transferred to a 0.1 L ammonium hydroxide 5L solution, stirred for 20 hours, filtered and dried for 48 hours in a vacuum pump to obtain 1.7 g of PANi emeraldine base (EB).

Synthesized polymers showed infrared absorption spectra at 1590 cm ^-1 , a typical quinoid functional group, 1495 cm ^-1 , a benzenoid functional group, and 3010 cm ^-1 , a result of CH aromatic stretching vibration. Synthesis of polyaniline was confirmed by ¹³ C-NMR spectral analysis by resonance analyzer showing characteristic peaks at 118, 137 ppm and 141 ppm, respectively.

Example 2

In this example, the procedure of Example 1 was repeated except that the reaction temperature was fixed at −25 ° C. during the polymerization of HCPANI. The reaction time was 6-8 hours to obtain HCPANI in the form of an emeraldine base. Synthesis of polyaniline in the form of an emeraldine base was confirmed through ultraviolet spectroscopy and nuclear magnetic resonance analysis for the synthesized compounds, respectively.

Example 3

In this example, the procedure of Example 2 was repeated except that the stirring speed was fixed at 350 rpm / min in the polymerization of HCPANI. The reaction time was 6-8 hours to obtain HCPANI in the form of an emeraldine base. Synthesis of polyaniline in the form of an emeraldine base was confirmed through ultraviolet spectroscopy and nuclear magnetic resonance analysis for the synthesized compounds, respectively.

Example 4

In this example, the procedure of Example 2 was repeated except that bis (2-chloroethyl) ether was used as the organic solvent in the polymerization of HCPANI. The reaction time was 6-8 hours to obtain HCPANI in the form of an emeraldine base. Synthesis of polyaniline in the form of an emeraldine base was confirmed through ultraviolet spectroscopy and nuclear magnetic resonance analysis for the synthesized compounds, respectively.

Example 5

In the present Example, the procedure of Example 2 was repeated except that an organic solvent in which chloroform and 4-methyl-2-pentanone were mixed at a volume ratio of 1: 1 was used as the organic solvent in the polymerization of HCPANI. The reaction time was 6-10 hours to obtain HCPANI in the form of emeraldine base. Synthesis of polyaniline in the form of an emeraldine base was confirmed through ultraviolet spectroscopy and nuclear magnetic resonance analysis for the synthesized compounds, respectively.

Example 6

In this example, the procedure of Example 3 was repeated except that 2: 1 was used based on the volume of the mixed organic solvent and the hydrochloric acid aqueous solution. The reaction time was 4 to 6 hours to obtain HCPANI in the form of an emeraldine base. Synthesis of polyaniline in the form of an emeraldine base was confirmed through ultraviolet spectroscopy and nuclear magnetic resonance analysis for the synthesized compounds, respectively.

Example 7: Intrinsic viscosity measurement of synthesized HCPANI

In this embodiment, the HCPANIdine base EB in the form of the emeraldine base synthesized through Examples 1 to 6 was dissolved in concentrated sulfuric acid at a concentration of 0.1 g / dl, respectively, and then measured intrinsic viscosity at 30 ° C. It was. Intrinsic viscosity for each polymer material is shown in Table 1 below.

Example 8 Measurement of Spectroscopic Properties of Synthesized HCPANI Solid Powders

¹³ C CPMAS NMR analysis was performed on the EB type HCPANI solid powder synthesized in Example 1. In this example, ¹³ C CPMAS nuclear magnetic resonance spectra were obtained from a Bruker NMR instrument at 100.6 MHz, spinning rate 7 KHz, and tetramethyl saline (TMS) was used as a standard. ^The results of the ¹³ C CPMAS analysis are shown in FIG. 2. As described above, the EB type HCPANI analyzed in this example had two distinct peaks around 140 ppm, and it was confirmed that a single peak was observed at 123 ppm and 158 ppm.

Example 9 Measurement of Solution State Spectroscopy Characteristics of Synthesized HCPANI

In this example, the solubility of the synthesized HCPANI was improved, and nuclear magnetic resonance was performed in solution.

First, in the present embodiment, EB-type HCPANI was synthesized by replacing with t-BOC to improve solubility. HCPANI was synthesized according to the same procedure as in Example 1, 1.0 g (5.5 × 10 ^-3 mol) of synthesized EB polymer and 4.8 g (2.2 × 10 ^-2 mol) of di-t-BOC (di-tert-butyldicarbonate) ) Was dissolved in 30 mL of NMP. Then 20 mL of pyridine was added and stirred at 90 ° C. for 6 hours. The reaction product was precipitated in excess water, filtered and washed with a 1: 1 solution of water and ethanol to give 0.6 g of purified t-BOC- polyaniline (HCPANI-t-BOC).

The resulting t-BOC-polyaniline was dissolved in CDCl ₃ and the NMR spectrum was obtained by a conventional method. The results are shown in FIG. 3. As can be seen from these results, HCPANI-t-BOC synthesized according to this Example shows four main peaks between 139.5 ppm and 160 ppm of chemical shift in solution ¹³ C NMR spectrum and 110 ppm of chemical shift. No and / or no identifiable peak between 130 ppm and 135 ppm of chemical shift and no peak between 149 ppm and 152 ppm of chemical shift. These results confirmed that the PANI synthesized according to the present invention was almost connected to the para position, and thus linearity was greatly improved.

Example 10 Particle Morphology of Synthesized HCPANI

In this example, the structure of HCPANI powder of the EB type synthesized in Examples 1, 3, 6 was observed through a scanning electron microscope.

3 to 5 show SEM pictures of the synthesized EB-type HCPANI powders, which are influenced by the stirring speed and the solvent ratio, respectively, according to the present embodiment. As can be seen in the picture, the powder of HCPANI synthesized according to the embodiment of the present invention shows that the shape of the hollow nanotube shape or nanopillar from the structure, such as foamed plastic consisting of nanoparticles. That is, the polymer synthesized according to the present invention was confirmed to have a three-dimensional structure of increasing the surface area compared to the polymer synthesized according to the conventional method.

Example 11 Measurement of Size and Distribution of HCPANI Particles

In this example, the particle size distribution of the product taken out of the reactor of Example 1 was measured. The measurement result according to the present embodiment is shown graphically in FIG. 7. The particle size measured by the particle light scattering method was about 10-30 micron, and the self-dispersion polymerization method showed that the reactants and products were well dispersed without the stabilizer.

Example 12 Measurement of Electrical Conductivity in CSA Solution of HCPANI

In this example, the electrical conductivity was measured after de-doping the HCPANI salt synthesized through Examples 1 to 6.

First, after de-doping the HCPANI salt synthesized in Examples 1 to 6, 1.57 g of each of the EB forms of HCPANI, 1.57 g of an organic acid, camphorsulfonic acid (CSA), was mixed in an equivalent ratio of 1: 2. The mixture was then dissolved in methacresol at a concentration of 2% (w / w) and a solution was prepared via sonication for 2 hours. 0.5 mL of this solution was cast on a slide glass and dried at 50 ° C. to prepare a film having a thickness of 0.5 to 80 μm. The measured electrical conductivity values for the films made from each HCPANI are shown in Table 1 below.

Table 1. Physical Properties of Synthesized HCPANI

Example Intrinsic Viscosity (dl / g Conductivity (S / cm) One 1.5 490 2 2.5 810 3  2.4 760 4 1.8 560 5 2.7 1350 6 2.5 790

In the above, a preferred embodiment of the present invention has been described, but the present invention is not limited thereto. Rather, those skilled in the art to which the present invention pertains will readily conceive various modifications and changes based on the embodiments of the present invention. However, it will be more apparent from the appended claims that such variations and modifications fall within the scope of the present invention without departing from the spirit of the invention.

The polyaniline synthesized according to the present invention has high solubility and excellent electrical conductivity due to its high linearity and low branching caused by side reactions and unique particle shape formed during polymerization.

Therefore, the polyaniline synthesized according to the present invention can be used for various electrodes, conductive films, fibers, coatings, blends with polymers, battery electrodes and organic semiconductors.

In addition, the low conductivity of the polyaniline synthesized according to the present invention in the mixture is excellent in electrical conductivity, and thus suitable for special applications such as corrosion protection, near infrared absorption, and conductive etch mask layers.

Claims (21)

A method of preparing a mixed solution by mixing an organic solvent with an aqueous hydrochloric acid solution containing an aniline unit and an initiator, and synthesizing polyaniline through a polymerization reaction of the aniline unit in a heterogeneous system at a temperature in the range of -45 to -10 ° C. The method of claim 1, The aniline unit is a method for synthesizing polyaniline having a structure represented by the following formula (I).

The method of claim 1, Wherein said polyaniline has a single peak at 123 ppm of chemical shift in ¹³ C CPMAS NMR spectrum. The method of claim 1, Wherein said polyaniline has a single peak at 158 ppm of chemical shift in ¹³ C CPMAS NMR spectrum. The method of claim 1, Wherein said polyaniline has a peak that is identifiable at 138 ppm chemical shift and 143 ppm chemical shift in ¹³ C CPMAS NMR spectrum, respectively. The method of claim 1, Wherein said polyaniline has a peak intensity at 138 ppm of chemical shift in the ¹³ C CPMAS NMR spectrum greater than a peak intensity at 143 ppm of chemical shift. The method of claim 1, The hydrogen acid is a polyaniline synthesis method, characterized in that the inorganic acid selected from hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid. The method of claim 1, The organic solvent has a solubility factor of 17 to 29, characterized in that the polyaniline synthesis method. The method of claim 1, Wherein said organic solvent comprises a hydrocarbon substituted with unsubstituted or substituted with halogen, carboxyl group, oxygen or hydroxy group, ether, unsubstituted or substituted with halogen, nitrobenzene, or a mixture thereof. The method of claim 1, The organic solvent is bis (2-chloroethyl) ether, 3-pentanol, 1,2-propanediol, butyl methyl ketone, diethyl carbonate, benzyl acetate, dimethyl glutarate, ethyl acetoacetate, ethylene glycol dimethyl ether, Ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, isobutyl isobutanoate, isobutyl acetate, 3-heptanol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, A method for synthesizing polyaniline comprising meta-cresol, 4-hydroxy-4-methyl-2-pentanone. The method of claim 1, The initiator is a method of synthesizing polyaniline comprising ammonium peroxide, hydrogen peroxide, manganese oxide, potassium dichromate, potassium iodide, ferric chloride, potassium permanganate, potassium bromide, or potassium chlorate. The method of claim 1, The initiator is a method for synthesizing polyaniline, characterized in that used in a ratio of 0.1 to 2 molar equivalents with respect to 1 mole of the aniline unit. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having a pore form such as foam, honeycomb or hollow capsule consisting of nanoparticles. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having a nano tube shape. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having a nanofiber shape. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having an electrical conductivity of 300 S / cm or more. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having an electrical conductivity of 500 S / cm or more. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having an electrical conductivity of 700 S / cm or more. The method of claim 1, The polyaniline is a method of synthesizing polyaniline having an electrical conductivity of 900 S / cm or more. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having an electrical conductivity of 1100 S / cm or more. The method of claim 1, The polyaniline is a method for synthesizing polyaniline having an electrical conductivity of 1300 S / cm or more.

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