Polyaniline and method thereof

Abstract

To provide polyanilines, articles thereof, and methods of forming polyanilines.SOLUTION: In at least one aspect, a polyaniline has a thermal stability of about 100°C or more, a weight average molecular weight (Mw) from about 50,000 g / mol to about 150,000 g / mol, and a molecular weight distribution (Mw / Mn) from about 1 to about 5. In at least one aspect, a film includes a polyaniline, the film having a hydrocarbon content of about 1 wt.% based on the total weight of the film. In at least one aspect, a method includes introducing an emulsion of an aqueous solution of aniline and an alkyl-substituted aryl sulfonic acid having a hydrocarbon content of 1 wt.% or less into a flow reactor, the flow reactor having a length of tubing having an inner diameter. The method includes polymerizing the monomer within the tube to form a polyaniline.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure provides polyaniline, articles thereof, and methods of forming the polyaniline. [Background technology]

[0002] By appropriately designing their chemical structures, conjugated polymeric materials can be used as additives to provide anti-corrosion and anti-static properties, and can be utilized in electronic applications such as organic light-emitting diodes (OLEDs), solar cells, semiconductors, display screens, and chemical sensors. However, conjugated polymeric materials often suffer from high manufacturing costs, material inconsistencies, and processing difficulties when prepared by batch processing.

[0003] Despite these advances, current methods limit the widespread use of conductive polymers. For example, polyaniline (PANI or "emeraldine") is one of the conductive polymers that has not been fully utilized due to high production costs, material inconsistencies, and batch processing difficulties. PANI is widely used in printed circuit board manufacturing as a final finish to protect copper and soldered circuits from corrosion. PANI is often prepared by chemical oxidative polymerization of aniline in aqueous solution. The material obtained by this technique is amorphous and insoluble in most organic solvents. In addition, conventional PANI products usually do not have the thermal stability that would be otherwise desired. Furthermore, to form PANI, many current flow reactors under evaluation use microfluidic chips or miniaturized columns as well as specialized equipment to control the flow devices, which adds cost and complexity to the process.

[0004] There is a need for new and improved polyanilines, articles comprising polyanilines, and methods of forming polyanilines. Summary of the Invention

[0005] The present disclosure provides polyaniline, articles thereof, and methods of forming the polyaniline.

[0006] In at least one embodiment, the polyaniline has a thermal stability of about 100° C. or greater, a weight average molecular weight (Mw) of about 50,000 g / mole to about 150,000 g / mole, and a molecular weight distribution (Mw / Mn) of about 1 to about 5.

[0007] In at least one embodiment, the membrane comprises polyaniline, and the membrane has a hydrocarbon content of about 1 wt %, based on the total weight of the membrane.

[0008] In at least one embodiment, the method includes introducing an aqueous emulsion of aniline and an alkyl-substituted aryl sulfonic acid having a hydrocarbon content of 1% or less by weight into a flow reactor having a length of tubing with an internal diameter, and polymerizing the monomers within the tube to form polyaniline.

[0009] In order that the above-mentioned features of the present disclosure may be understood in detail, a more detailed description of the present disclosure, briefly summarized above, may be had by reference to examples, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure, and therefore should not be considered as limiting the scope of the present disclosure, which may admit of other equally effective aspects. [Brief description of the drawings]

[0010] [Figure 1A] FIG. 1 is a diagram of an exemplary flow reactor system according to one or more embodiments. [Figure 1B] FIG. 1 is a diagram of an exemplary continuous flow reactor system according to one or more embodiments. [Figure 1C] FIG. 1 is a diagram of an exemplary parallel flow reactor system according to one or more embodiments. [Diagram 2]FIG. 1 is a process flow diagram of a polymerization process using the systems and methods according to one or more embodiments. [Diagram 3] FIG. 2 is a cross-sectional view of an inner diameter region of a flow reactor according to one or more embodiments. [Figure 4] FIG. 2 is a cross-sectional view of the inner diameter region of a flow reactor having a conductive polymer reaction product occupying a portion of the inner diameter region, according to one or more embodiments. [Diagram 5] FIG. 1 is a process flow diagram of a polymerization process using the systems and methods according to one or more embodiments. [Figure 6] FIG. 1 is a process flow diagram of a method for polymerization of PANI-DNNSA using systems and methods according to one or more embodiments. [Figure 7A] 1 is a graph showing gel permeation results (refractive index vs. retention volume (mL)) using a refractive index detector for polyaniline, according to one or more embodiments. [Figure 7B] 1 is a graph showing gel permeation results (viscometer differential pressure vs. retention volume (mL)) using a viscometer for polyaniline, according to one or more embodiments. [Figure 8] 1 is a graph showing thermal stability data (resistance vs. temperature) of polyaniline according to one or more embodiments. [Figure 9] 1 is a graph showing thermal stability data (resistance vs. temperature) of polyaniline according to one or more embodiments. [Figure 10a] 1 is an overlaid FTIR spectrum of DNNSA according to one or more embodiments. [Figure 10b] 1 is an overlaid FTIR spectrum of DNNSA according to one or more embodiments.

[0011] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements that are common to each of the figures, and it is contemplated that elements and features of one embodiment may be advantageously incorporated in other embodiments without further detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present disclosure provides polyaniline, articles thereof, and methods of forming the polyaniline. The polyaniline of the present disclosure can be substantially free of by-products such as non-sulfonated hydrocarbons, which results in reduced "outgassing" of the polyaniline compared to conventional polyanilines. The polyaniline of the present disclosure has a thermal stability of about 100° C. or higher, a weight average molecular weight (Mw) of about 50,000 g / mol to about 150,000 g / mol, and a molecular weight distribution (MWD) of about 1 to about 5. The reduced outgassing and improved molecular weight properties of the polyaniline of the present disclosure result in improved thermal stability compared to conventional polyanilines.

[0013] The method of the present disclosure includes forming the polyaniline of the present disclosure by using aniline and an alkyl-substituted aryl sulfonic acid (e.g., dinonylnaphthalene sulfonic acid (DNNSA)). The alkyl-substituted aryl sulfonic acid of the method of the present disclosure has a non-sulfonated hydrocarbon content of 1 wt% or less. Conventional alkyl-substituted aryl sulfonic acids (e.g., DNNSA) have a non-sulfonated hydrocarbon content of more than 1 wt%. The non-sulfonated hydrocarbons may include branched or straight-chain paraffins and / or aromatic compounds (e.g., benzene and naphthalene). For example, it was hypothesized that the non-sulfonated hydrocarbon content of conventional DNNSA samples was due to decomposition of the sulfonic acid when placed under ultra-high vacuum for storage. However, it was discovered that the non-sulfonated hydrocarbons were already present in the DNNSA samples and were likely by-products of the conventional DNNSA manufacturing process. For example, the use of DNNSA with a non-sulfonated hydrocarbon content of 1 wt% or less can provide polyaniline with reduced outgassing and improved thermal stability. Polyaniline with reduced outgassing and improved thermal stability, and articles thereof, provide compositions, coatings, layers, etc. for a wide range of uses in articles (aircraft, ground vehicles, wind turbines, satellites, etc.).

[0014] Polyaniline The polyaniline of the present disclosure may be an acidified polyaniline (hereafter referred to as PANI-acid or "emeraldine salt") or a neutral polyaniline. The acidified form of polyaniline may have conjugate-base counterions (as anionic ligands), as described in more detail below. Neutral polyaniline may be formed by neutralizing the PANI-acid under any suitable conditions, such as treating the PANI-acid with sodium hydroxide solution and washing the neutralized polymer product with water.

[0015] The molecular weight data herein (Mw, Mn, Mz, Mp, and Mw / Mn) refer to the neutral polyaniline (i.e., the uncharged, undoped form of polyaniline), in other words, the molecular weight of polyaniline herein does not include molecular weight added by the presence of dopants such as acids or DNNSA.

[0016] The polyanilines of the present disclosure may have a number average molecular weight (Mn) of about 50,000 g / mol to about 150,000 g / mol (e.g., about 75,000 g / mol to about 100,000 g / mol, alternatively, about 100,000 g / mol to about 130,000 g / mol). The polyanilines of the present disclosure may have a number average molecular weight (Mn) of about 50,000 g / mol to about 100,000 g / mol (e.g., about 60,000 g / mol to about 80,000 g / mol, alternatively, about 80,000 g / mol to about 100,000 g / mol).

[0017] The polyanilines of the present disclosure may have a molecular weight distribution (MWD) as determined by gel permeation chromatography of about 1 to about 5 (e.g., about 1 to about 4, about 1 to about 3, about 1.2 to about 2.5, about 1.3 to about 1.7). MwD may be determined by dividing Mw by Mn, and may be referred to herein as "Mw / Mn".

[0018] The polyaniline of the present disclosure may have a Z-average molecular weight (Mz) of about 75,000 g / mol to about 250,000 g / mol (e.g., about 100,000 g / mol to about 250,000 g / mol, about 150,000 g / mol to about 250,000 g / mol). Mz indicates the high molecular content of the polymer. For example, the Mz value of the polyaniline of the present disclosure may be higher than that of conventional polyanilines, which may provide improved processability compared to conventional polyanilines.

[0019] The polyanilines of the present disclosure may have a peak average molecular weight (Mp) of about 50,000 g / mol to about 150,000 g / mol (e.g., about 100,000 g / mol to about 150,000 g / mol, about 110,000 g / mol to about 140,000 g / mol, about 113,000 g / mol to about 136,000 g / mol). The peak average molecular weight indicates the molecular weight mode of the polymer distribution and highlights the increased molecular weight of the polyanilines of the present disclosure.

[0020] The molecular weight characteristics of polyaniline (e.g., Mw, Mn, Mz, Mp) can be determined using gel permeation chromatography. The mobile phase can be 0.02 M ammonium formate (AF) in N-methylpyrrolidone (NMp). Universal calibration techniques can be used to measure the molecular weight distribution utilizing a viscosity detector and a refractive index detector. Prior to use, the solution can be filtered through a 0.45 micron filter. Polyaniline samples can be precipitated with spectroquality methanol, washed four times with methanol, and collected using vacuum filtration. These samples can be air-dried, dissolved in AF-MNPs, passed through a 0.2 micron filter, and passed directly into GPC vials for analysis.

[0021] The polyaniline articles (e.g., films) of the present disclosure may have a hydrocarbon content of about 1 wt% or less (e.g., about 0.5 wt% or less, about 0.1 wt% or less, about 0.001 wt% to about 1 wt%, about 0.01 wt% to about 0.5 wt%) based on the total weight of the sample (e.g., film). For example, the film may have a hydrocarbon content of about 1 wt% or less based on the total weight of the film (e.g., the total weight of the hydrocarbon content, polyaniline, and dopant). Hydrocarbons include C1-C20 paraffins and aromatic hydrocarbons (e.g., benzene and naphthalene). In at least one embodiment, the hydrocarbon is naphthalene.

[0022] Polyaniline articles (e.g., films) of the present disclosure may have an outgassing percentage according to ASTM E595-93 of about 0.5% or less (e.g., about 0.3% or less, about 0.1% or less, about 0.05% or less, about 0.01% or less).

[0023] The polyaniline of the present disclosure may have a thermal stability of about 100°C or higher (e.g., about 110°C or higher, about 120°C or higher, about 120°C to about 160°C, about 130°C to about 160°C, about 140°C to about 160°C, about 150°C to about 160°C). Thermal stability can be determined by spinning the polyaniline onto a glass slide and drying the spin-coated sample at 70°C. A silver bar can be applied to the edge of the slide for electrical contact. The sample can be exposed to a constant temperature (e.g., 150°C) for 24 hours in a convection oven. The resistance of the sample can then be measured to determine thermal stability.

[0024] In at least one embodiment, the polyaniline is a PANI-acid represented by formula (I): TIFF0007644570000001.tif48170, R 1 , R 2 , R 3 , and R 4Each instance of is independently selected from hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 aryl, substituted or unsubstituted C1-C20 alkaryl, substituted or unsubstituted C1-C20 arylalkyl, substituted or unsubstituted C1-C20 alkoxyl, and halogen (e.g., fluoro, chloro, bromo, or iodo); 1 , R 2 , R 3 , and R 4 one or more instances of are optionally substituted with a group independently selected from C1-C20 alkoxyl, and halogen (e.g., fluoro, chloro, bromo, or iodo); A - Each example of is an anionic ligand, n is an integer such that the polyaniline has a weight average molecular weight (Mw) of about 55,000 g / mol to about 80,000 g / mol (e.g., about 60,000 g / mol to about 75,000 g / mol, about 65,000 g / mol to about 70,000 g / mol).

[0025] R 1 , R 2 , R 3 , and R 4 Each instance of is independently selected from hydrogen and unsubstituted C1-C20 alkyl. In one or more embodiments, C1-C20 alkyl is selected from methyl, ethyl, propyl, n-butyl, iso-butyl, sec-butyl, n-pentyl, iso-pentyl, sec-pentyl, n-hexyl, iso-hexyl, and sec-hexyl. In at least one embodiment, R 1 , R 2 , R 3 , and R 4 Each instance of is hydrogen.

[0026] In at least one embodiment, the C1-C20 aryl is selected from phenyl and naphthyl. In at least one embodiment, the C1-C20 alkaryl is benzyl. In at least one embodiment, the C1-C20 arylalkyl is toluyl, mesityl, or ethylbenzyl.

[0027] In at least one embodiment, A - Each example of A is an anionic ligand independently selected from sulfonic acid, hydroxide, and halogen (e.g., fluoro, chloro, bromo, or iodo). - is a sulfonic acid such as dinonylnaphthalenesulfonic acid.

[0028] Methods for preparing alkyl-substituted aryl sulfonic acids, anilines, and polyanilines A representative, non-limiting reaction scheme for forming the polyaniline of the present disclosure is shown below in Scheme 1. As shown in Scheme 1, aniline is treated with an alkyl-substituted arylsulfonic acid and a catalyst to form the polyaniline represented by formula (I). TIFF0007644570000002.tif119170

[0029] R of formula (I) in scheme 1 1 , R 2 , R 3 , R 4 , and A - is as explained above for formula (I).

[0030] For the aniline monomer in Scheme 1, R 1 , R 2 , R 3 , and R 4 Each instance of is independently selected from hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 aryl, substituted or unsubstituted C1-C20 alkaryl, substituted or unsubstituted C1-C20 arylalkyl, substituted or unsubstituted C1-C20 alkoxyl, and halogen (e.g., fluoro, chloro, bromo, or iodo); 1 , R 2 , R 3 , and R 4 one or more instances of are optionally substituted with a group independently selected from C1-C20 alkoxyl, and halogen (e.g., fluoro, chloro, bromo, or iodo); R 5 is hydrogen.

[0031] In at least one embodiment, R of the aniline monomer of Scheme 1 1 , R 2 , R 3 , and R 4 Each instance of is independently selected from hydrogen and unsubstituted C1-C20 alkyl. In one or more embodiments, C1-C20 alkyl is selected from methyl, ethyl, propyl, n-butyl, iso-butyl, sec-butyl, n-pentyl, iso-pentyl, sec-pentyl, n-hexyl, iso-hexyl, and sec-hexyl. In at least one embodiment, R 1 , R 2 , R 3 , and R 4 Each instance of is hydrogen.

[0032] The alkyl-substituted aryl sulfonic acids (or solutions thereof, e.g., organic solutions) of the present disclosure can have a non-sulfonated hydrocarbon content of 1% or less by weight and can be dialkyl-substituted naphthyl sulfonic acids, such as DNNSA. Alkyl-substituted aryl sulfonic acids, such as DNNSA, having a non-sulfonated hydrocarbon content of 1% or less by weight can be commercially available from King Industries.

[0033] In at least one embodiment, the alkyl substituted aryl sulfonic acid (e.g., DNNSA) (or a solution thereof) has a hydrocarbon content of about 1 wt. % or less (e.g., about 0.5 wt. % or less, about 0.1 wt. % or less, about 0.001 wt. % to about 1 wt. %, about 0.01 wt. % to about 0.5 wt. %) based on the total weight of the acid (acid without additional solvent present, e.g., isopropanol).

[0034] The molar ratio of alkyl substituted aryl sulfonic acid:aniline in the methods of the present disclosure can be from about 0.2:1 to about 2:1 (e.g., from about 0.3:1 to about 1:1, from about 0.8:1 to about 1:0.8, about 1:1).

[0035] The catalyst of the present disclosure may include any suitable ammonium or sulfate catalyst (e.g., ammonium persulfate).

[0036] Furthermore, the addition of hydrocarbon solvents may be undesirable. For example, adding high levels of heptane or hexane will prevent the formation of emulsions. For example, if the process is run with only DNNSA in heptane and no 2-butoxyethanol, the reaction may not proceed far enough to yield a soluble product.

[0037] Flow Reactor Treatment Described herein is a process for forming the disclosed polyaniline (hereafter referred to as PANI-acid) as a solvent-soluble polymer by flow reactor chemistry using alkyl-substituted aryl sulfonic acids (e.g., DNNSA). The disclosed system and method provide a unique process sequence for direct collection of purified emeraldine salt without post-reactor manipulation. The system and method provide an improvement over known methods for synthesizing conductive polymers, specifically conductive polymer salts (e.g., PANI-acid). The system and method have very short reaction times, which cannot be achieved using conventional methods that require long reaction times.

[0038] For example, the present systems and methods provide improved efficient and controlled synthesis of polyaniline (PANI) salts as soluble and intrinsically conductive polymers. Continuous flow synthesis of PANI-salts or "emeraldine salts" is described herein using a flow reactor. In some embodiments, the flow reactor comprises a microfluidic (1 to about 750 um inner diameter) tube reactor. In some embodiments, the microfluidic tube comprises a fluoropolymer (e.g., TEFLON®). The tube reactor provides a surface suitable for deposition of the polymer being formed and easy for direct purification of the conductive polymer salt.

[0039] As used herein, the term "flow reactor" includes microflow reactors, which is used herein as a flow reactor having flow dimensions (e.g., tube inner diameter (ID)) less than 1 mm (1000 microns).

[0040] As described further below, in some embodiments, as the polymerization reaction proceeds, a large portion of the polymer product deposits on the walls of the tube, and the polymer product can be purified by washing with water to remove water-soluble reactants, reagents, and by-products.

[0041] The conductive polymer salts formed in the flow reactor and deposited on the walls of the tubes can be eluted with organic solvents to provide soluble conductive polymer salts suitable for solid casting, film formation, or precipitation. The apparatus can be configured for in situ characterization (e.g., UV-Vis spectroscopy, infrared, and / or mass spectroscopy).

[0042] An apparatus and associated methods for polymerizing at least one reactant are described. In certain embodiments, the apparatus is a microfluidic device comprising a mixing chamber and a microchannel. Additionally, the reactor may further comprise an output chamber and a detection unit operably connected to the microchannel.

[0043] Any suitable apparatus (e.g., a flow reactor) may be used to form the polyaniline of the present disclosure, such as those described in U.S. Patent Application No. 10,118,922, which is incorporated by reference herein for purposes of U.S. law.

[0044] Referring to FIG. 1A, a flow reactor system 100 is shown. A first reactant 10 (e.g., aniline) and a second reactant 20 (e.g., alkyl-substituted aryl sulfonic acid) are introduced into a first mixing unit 30. The reactor system 100 shown in FIG. 1A can produce conductive polymer salts (mass per unit time) more efficiently than conventional macroscale devices or batch reactors. The flow reactor system 100 can operate at a processing temperature range from room temperature to about 250° C. (e.g., processing temperatures below 100° C.). In some embodiments, ambient temperature is between about 50° F. (10° C.) and about 90° F. (32° C.). In some embodiments, the reactants 10, 20 are introduced separately into the first mixing unit 30 at a predetermined flow rate and / or at a predetermined concentration so that they are mixed in a desired molar ratio before being introduced into the flow reactor. In other embodiments, the reactants 10, 20 are introduced together in a first mixing unit 30 so that they are mixed in a desired molar ratio before being introduced into the flow reactor. The first mixing unit 30 may be any suitable mixing device. In some embodiments, the mixing device is a high-speed or ultra-high-speed mixing device capable of emulsifying one or more solutions (e.g., aqueous and non-aqueous solutions). In some embodiments, the first reactant 10 is included in an aqueous solution and the second reactant 20 is included in a non-aqueous solution. The first mixing unit 30 is designed to emulsify the first reactant 10 and the second reactant 20. A third reactant 50 joins the first and second reactants in a second mixing unit 60. In some embodiments, the reactant 50 is a catalyst. After mixing in the second mixing unit 60, the reactants are introduced into a tube 70 via an inlet port 65. The tube 70 is equipped with an outlet port 80 that can be monitored by an analytical instrument 90. The analytical instruments 90 may include spectroscopic instruments that examine and analyze materials flowing from the exit port 80, such as unreacted materials and / or reaction products. Spectroscopic instruments include UV-Vis, IR (near, mid, and far infrared), and mass spectrometry. Other analytical and interrogation techniques such as capacitance, pH, etc. may be used. A pressure regulation unit 67 may be positioned at the outlet of the flow reactor 70 to monitor changes in pressure during the polymerization process or during the course of a collection step of the polymerized material.Information from the pressure regulation unit 67 can be used by the controller to halt the introduction of reactants to the flow reactor. For example, an additional pressure regulation unit 67 can be positioned at the inlet of the flow reactor 70 to monitor pressure changes during the course of the process. A fluid line 69 can be individually fluidly connected to the flow reactor 70, whereby a purge medium 66 (e.g., water) or a collection medium 68 (e.g., a solvent) can be introduced to collect the polymerization product from the flow reactor unit 70.

[0045] In some embodiments, the flow reactor system 100 has a single inlet port to the tube 70. In other embodiments, the flow reactor system 100 has additional inlet ports positioned between the inlet port 65 and the exhaust port 80. The tube 70 can be coiled to provide an expanded tubular flow reactor, as shown in FIG. 1A.

[0046] In some embodiments, tube 70 is contained within housing 40. Housing 40 provides temperature control and / or support and / or protection from damage to tube 70. In some embodiments, housing 70 has an interior surface that surrounds at least a portion of tube 70 such that the wound tube 70 is at least partially contained within housing 40. In some embodiments, housing 40 is configured to provide temperature control (including heating and / or cooling) to tube 70.

[0047] As shown in FIG. 1B, an alternative flow reactor configuration 100a is shown having multiple tubes 70a, 70b arranged in a serially connected wound configuration. The tubes 70a, 70b may be dimensionally the same or may have different lengths and / or different internal diameters. In this configuration, the housing may be bifurcated into separate sections 40a, 40b that receive the tubes 70a and 70b. These sections may be individually operated to heat and / or cool the tubes. Alternatively, the flow reactor configuration 100a may have a single housing that receives the tubes 70a, 70b. As opposed to a parallel array configuration of tubes where the process stream is split before entering the flow reactor, the serial array maximizes the amount of time the reaction mixture is maintained in a diffusion-limited condition. Without being bound to any particular theory, maintaining the reaction mixture in a diffusion-limited condition provides an improvement of the presently disclosed reaction for producing a conductive polymer salt from reactants in an emulsion compared to batch processing. The methods and systems disclosed herein provide such diffusion-limited conditions for emulsions of reactants.

[0048] Referring to FIG. 1C, an exemplary flow reactor system 100b is shown. A plurality of flow reactor units 70c, 70d, and 70e are shown in a parallel flow configuration. Each flow reactor 70c, 70d, and 70e may be individually isolated via flow control valves 63. The flow control valves 63 are positioned at the inlet and outlet of each flow reactor to introduce the monomer solution into the corresponding flow reactor. The flow control valves 63 may be manually operated and / or solenoid-based configured for computer control using conventional controllers. The flow control valves 63 may include one or more check valves to prevent backflow of the dispersion. One or more pressure regulation units 67 may be positioned at one or more outlets of the flow reactors to monitor pressure changes during the polymerization process or during the process of collecting the polymerized material. Additional pressure regulation units 67 may be further positioned at the inlet of each flow reactor. Flow control valve 63 may be coupled to pressure data from the controller to isolate one or more of flow reactors 70c, 70d, and 70e to activate purge and / or polymer recovery. In this configuration, flow reactor system 100b may be operated continuously by selectively isolating one or more of flow reactor units 70c, 70d, and 70e for polymerization product recovery and / or maintenance while maintaining introduction of monomer to one or more of the remaining flow reactor units. Alternatively, flow reactor system 100b may be operated semi-continuously, for example, by temporarily ceasing introduction of monomer to one or more of flow reactor units 70c, 70d, and 70e. Additional fluid lines 69 may be individually fluidly connected to one or more of the flow control valves 63 for introducing a purge medium 66 (e.g., water) or a collection medium 68 (e.g., a solvent) to selectively collect polymerization products from one or more of the flow reactor units 70c, 70d, and 70e.One or more of the flow reactor units 70c, 70d, and 70e may be physically removed from the flow reactor system 100b for transport, with or without the polymerization product collected from the inner diameter of the tubing.

[0049] Referring to FIG. 2, a process flow 201 is shown as an example of the method disclosed herein. Thus, in block 205, an emulsion of aqueous monomer and acid in a non-aqueous solvent is shown to be prepared. In block 210, the emulsion and catalyst are shown to be introduced into the microreactor tube. After a predetermined time, the flow of one or more of the reactants can be stopped, and optionally, washing of the microreactor tube with water can be performed, as shown in block 215. Block 215 can be performed to remove unreacted reactants and / or low molecular weight products. In block 220, recovery of the polymer from the microreactor tube with an organic solvent is performed.

[0050] 3 and 4, a cross section of a tube 300 is shown with the inner surface 310 of the tube bore having an inner diameter D. In some embodiments, the maximum diameter is less than the diameter at which the benefits of diffusion limited reactions are diminished. This maximum diameter may be on the order of 4000 microns, similar to tube diameters used in high pressure tubing. In other embodiments, optimal results may be obtained using diameters of less than 4000 microns, less than 3000 microns, or less than 1000 microns, down to about 100 microns. Without being bound to any particular theory, it is believed that the faster kinetics of the reactions disclosed and described herein can be achieved by reducing the inner diameter dimensions of the reactor tube to less than 10 in microfluidic systems. 4 From 10 6This is believed to occur when the capillary tube 300 is allowed to shrink to about 1 / 2 the volume of reaction mixture per unit time. This has previously been reported as some balance of reaction volume per unit time. In one embodiment, the capillary tube 300 is made of glass, metal, plastic, or glass or metal coated on the inside surface with a polymer (e.g., a fluoropolymer). The tube may be encased in another polymer or coated with a metal.

[0051] The tube length may be selected based on the ability of the selected components of the system to handle pressure (pump power, burst strength of the tube, fittings, etc.). The maximum length of the tube suitable for use with the presently disclosed system is a function of back pressure and the ability to transport product through the entire length of the tube. In some embodiments, the system may be configured to operate with connected tube lengths having inner tube diameters such that the system operates at about 20 bar (280 psi) or less. In some embodiments, the length of the tube does not exceed 500 meters, with tubes having inner diameters of less than 4000 microns. In other embodiments, the tube 300 is a less than 1000 micron diameter tube (microfluidic tube) that is about 100 meters or less in length. Other combinations of tube diameter and length may be used commensurate with the operating parameters of the system and the desired reaction volume per unit time.

[0052] The cross section of the tube may be any shape, but is preferably circular. In some embodiments, as shown in FIG. 4, polymerization occurs at the inner surface 310 of the tube bore. The polymerization product 400 restricts the inner diameter D to a reduced diameter D'. In some embodiments, the reduction in the inner tube diameter, or inner diameter D, is symmetric about the longitudinal axis AA, BB. In some embodiments, the reduction in the inner tube diameter, or inner diameter D, is asymmetric about the longitudinal axis AA, BB. The reduction in diameter D of the tube 300 to diameter D' creates a back pressure that can be measured and / or used in part to control the processes described herein.

[0053] This back pressure can be monitored, and in the early stages of polymerization, the back pressure at time T1 corresponds to the viscosity and flow rate of the emulsified reaction mixture being fed into the tube 300. During time period T2, as the polymerization reduces the inner diameter of the tube 300, the back pressure begins to increase and approaches a threshold value. In some embodiments, the system is designed to stop the polymerization when the back pressure value reaches a predetermined threshold value. The rate of change of the back pressure, as shown in time period T2, can be adjusted by manipulating the viscosity of the reactants, the molar concentration of the reactants and / or catalyst, the temperature, the flow rate, and combinations thereof, taking into account the burst strength of the capillary tube and other reactor parameters. FIG. 5 shows a process flow diagram 500 depicting an embodiment of the presently disclosed method. Thus, at block 505, the emulsion of reactants and catalyst is shown to be pumped into the microreactor tube. At block 510, the back pressure of the emulsion of reactants is shown to be monitored during the polymerization process. It is contemplated that conventional pressure monitoring equipment, either external or electrical, with a pumping device may be used. Introduction of the reactant emulsion is stopped once the threshold backpressure is reached, as shown in block 515. Block 520 shows the polymer product being recovered from the microreactor tube by washing with an organic solvent.

[0054] As an example, the method disclosed herein can be applied to the preparation of the polyaniline of the present disclosure. In at least one embodiment, the polyaniline formed by the method of the present disclosure is polyaniline-dinonylnaphthalene sulfonate ("PANI-DNNSA"). PANI-DNNSA is a conductive polymer for electrical applications such as organic light-emitting diodes (OLEDs), solar cells, semiconductors, display screens, and chemical sensors.

[0055] Thus, as an example, a continuous flow synthesis process for PANI-DNNSA salts is provided. A flow apparatus was designed to allow the addition of an oxidation reagent to a preformed emulsion of aqueous aniline and organic soluble DNNSA. For example, an emulsion polymerization of equimolar amounts of aniline and DNNSA in the presence of ammonium persulfate as an oxidation catalyst can be carried out. This reaction is shown below in Scheme 2. TIFF0007644570000003.tif88170

[0056] Thus, referring to FIG. 6, a process flow diagram 600 is shown. In blocks 602 and 604, an aqueous composition including aniline and a non-aqueous composition including alkyl-substituted aryl sulfonic acid are introduced into a first mixer, respectively. In block 610, forming an emulsion of reactants in the first mixer is performed. In block 615, introducing the emulsion of catalyst and reactants into a second mixer is performed. In block 620, introducing into the microreactor tube and obtaining a threshold back pressure is performed. In block 625, stopping the introduction of the emulsion of reactants and catalyst into the microreactor tube is performed. Optionally, in block 630, the microreactor tube can be washed with water to remove unreacted materials and / or low molecular weight polymers. In block 635, recovering the polyaniline polymer salt from the microreactor tube with an organic solvent is performed.

[0057] Various Aspects The present disclosure provides, inter alia, the following aspects, each of which may be considered to optionally include any alternative aspects.

[0058] Clause 1 A polyaniline having a weight average molecular weight (Mw) of about 50,000 g / mol to about 150,000 g / mol as determined by gel permeation chromatography, and a molecular weight distribution (Mw / Mn) of about 1 to about 5 as determined by gel permeation chromatography.

[0059] Clause 2 2. The polyaniline of clause 1, wherein the polyaniline is substantially free of hydrocarbons.

[0060] Clause 3 3. The polyaniline according to clause 1 or 2, wherein the polyaniline is an acidified polyaniline having multiple conjugated base counter ions.

[0061] Clause 4 4. The polyaniline of any one of clauses 1 to 3, wherein the polyaniline has a Mw of about 55,000 g / mol to about 80,000 g / mol as determined by gel permeation chromatography.

[0062] Clause 5 5. The polyaniline of any one of clauses 1 to 4, wherein the polyaniline has a Mw of about 110,000 g / mol to about 140,000 g / mol as determined by gel permeation chromatography.

[0063] Clause 6 6. The polyaniline of claim 1, wherein the polyaniline has a number average molecular weight (Mn) of about 50,000 g / mol to about 100,000 g / mol as determined by gel permeation chromatography.

[0064] Clause 7 7. The polyaniline according to any one of clauses 1 to 6, wherein the polyaniline has a Mn of about 72,000 g / mol to about 74,000 g / mol.

[0065] Clause 8 8. The method of any one of clauses 1 to 7, wherein the polyaniline has a molecular weight distribution (Mw / Mn) of about 1 to about 5 as determined by gel permeation chromatography.

[0066] Clause 9 9. The method of any one of clauses 1 to 8, wherein the polyaniline has a Mw / Mn of about 1.5 to about 1.9 as determined by gel permeation chromatography.

[0067] Clause 10 10. The polyaniline of any one of clauses 1 to 9, wherein the polyaniline has a Z-average molecular weight (Mz) of about 100,000 g / mol to about 250,000 g / mol as determined by gel permeation chromatography.

[0068] Clause 11 11. The polyaniline according to any one of the preceding clauses, wherein the polyaniline has a Mz of about 152,000 g / mol to about 204,000 g / mol.

[0069] Clause 12 12. The polyaniline according to any one of the preceding clauses, wherein the polyaniline has a peak average molecular weight (Mp) of about 50,000 g / mol to about 150,000 g / mol.

[0070] Clause 13 13. The polyaniline according to any one of the preceding clauses, wherein the polyaniline has an Mp of about 113,000 g / mol to about 136,000 g / mol.

[0071] Clause 14 14. The polyaniline according to any one of clauses 1 to 13, wherein the polyaniline has a thermal stability of about 100° C. or greater.

[0072] Clause 15 15. The polyaniline according to any one of clauses 1 to 14, wherein the polyaniline has a thermal stability of about 150°C to about 160°C.

[0073] Clause 16 The polyaniline has the formula (I): Represented by TIFF0007644570000004.tif48170, In the formula, R 1 , R 2 , R 3 , and R 4 each instance of R is independently selected from hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxyl, and halogen; 1 , R 2 , R 3 , and R 4 one or more instances of are optionally replaced with a group independently selected from C1-C20 alkoxyl, and halogen; A - are anionic ligands; 16. The polyaniline of any one of the preceding clauses, wherein n is an integer such that the polyaniline has a weight average molecular weight (Mw) of about 55,000 g / mol to about 80,000 g / mol.

[0074] Clause 17 17. The polyaniline of any one of the preceding clauses, wherein the polyaniline has a Mw of about 65,000 g / mol to about 70,000 g / mol.

[0075] Clause 18 R 1 , R 2 , R 3 , and R 4 18. The polyaniline of any one of the preceding clauses, wherein each instance of is independently selected from hydrogen and unsubstituted C1-C20 alkyl.

[0076] Clause 19 R 1 , R 2 , R 3 , and R 4 19. The polyaniline of any one of clauses 1 to 18, wherein each instance of is hydrogen.

[0077] Clause 20 A -20. The polyaniline of any one of clauses 1 to 19, wherein each example of is dinonylnaphthalenesulfonic acid.

[0078] Clause 21 21. A membrane comprising the polyaniline of any one of clauses 1 to 20, wherein the membrane has a hydrocarbon content of about 1 wt. % or less, based on the total weight of the membrane.

[0079] Clause 22 22. The membrane of clause 21, wherein the membrane has a hydrocarbon content of about 0.5 wt.% or less, based on the total weight of the membrane. Clause 23 23. The membrane according to clause 21 or 22, wherein the hydrocarbon is naphthalene.

[0080] Clause 24 24. The membrane of any one of clauses 21 to 23, wherein the membrane has an outgassing percentage of about 0.5% or less.

[0081] Clause 25 25. The membrane of any one of clauses 21 to 24, wherein the membrane has an outgassing rate of about 0.1% or less.

[0082] Clause 26 introducing an emulsion of aniline in an aqueous solution and an organic solvent solution of an alkyl-substituted aryl sulfonic acid having a hydrocarbon content of 1% or less by weight into a flow reactor having a length of tubing having an inner diameter; polymerizing the monomer within the tube to form polyaniline; A method comprising:

[0083] Clause 27 27. The method of claim 26, further comprising introducing a catalyst into the emulsion.

[0084] Clause 28 28. The method of claim 26 or 27, further comprising introducing a catalyst into the flow reactor.

[0085] Clause 29 29. The method of any one of clauses 26 to 28, wherein the length of tube is wound.

[0086] Clause 30 30. The method of any one of clauses 26 to 29, wherein the flow reactor comprises a plurality of tubes arranged in a parallel flow configuration.

[0087] Clause 31 31. The process of any one of clauses 26 to 30, wherein the molar ratio of aniline to acid is between about 1:1 and about 0.2:1.

[0088] Clause 32 32. The method of any one of clauses 26 to 31, wherein the catalyst is ammonium persulfate.

[0089] Clause 33 33. The method of any one of clauses 26 to 32, wherein the alkyl substituted aryl sulfonic acid is dinonyl naphthyl sulfonic acid.

[0090] Clause 34 34. The method of any one of clauses 26 to 33, wherein the solution of alkyl substituted aryl sulfonic acid in organic solvent has a hydrocarbon content of 0.5% by weight or less.

[0091] Clause 35 35. The method of any one of clauses 26 to 34, wherein the solution of alkyl substituted aryl sulfonic acid in organic solvent has a hydrocarbon content of 0.1 wt% or less.

[0092] Clause 36 36. The method of any one of clauses 26 to 35, wherein the solution of alkyl substituted aryl sulfonic acid in organic solvent has 0.5% by weight or less of naphthalene.

[0093] Clause 37 37. The method of any one of clauses 26 to 36, further comprising recovering the polyaniline from the tube.

[0094] Clause 38 38. The method of any one of clauses 26 to 37, wherein the polyaniline has a Mw of about 50,000 g / mol to about 150,000 g / mol as determined by gel permeation chromatography.

[0095] Clause 39 39. The method of any one of clauses 26 to 38, wherein the polyaniline has a Mw of about 65,000 g / mol to about 70,000 g / mol as determined by gel permeation chromatography.

[0096] Clause 40 40. The method of any one of clauses 26 to 39, wherein the polyaniline has a Mw / Mn of about 1.5 to about 1.9 as determined by gel permeation chromatography.

[0097] Clause 41 41. The method of any one of clauses 26 to 40, wherein the polyaniline has a thermal stability of about 100° C. or greater.

[0098] Clause 42 43. The method of any one of clauses 26 to 42, wherein the polyaniline has a thermal stability of about 150°C to about 160°C.

[0099] Working Example PANI / DNNSA was synthesized using an emulsion polymerization process developed by Kinlen et al. (Macromolecules, 1998, 31, 1735-1744). PANI / DNNSA (pur) synthesis was performed using five purified Nacure samples (C, D, E, F, H) obtained from King Industries. For conductivity measurements, all samples were spin-coated on glass at 2000 rpm and heated at 70°C for 1 hour. All film thickness measurements were performed using a Bruker Contour GT-K1 white light interferometer. All films were cast on glass substrates using silver ink as contacts unless otherwise noted. Resistance was measured using a Keithley semiconductor characterization system with a voltage sweep from -10V to 10V.

[0100] material All chemicals were used as is without further purification. DNNSA (Nacure 1051) purified in 2-butoxyethanol was obtained from King Industries. Aniline, ammonium persulfate, and xylene were obtained from Sigma-Aldrich. NMP was obtained from Fisher Scientific. All materials were reagent grade.

[0101] method PANI / DNNSA Refined DNNSA batch PANI / DNNSA (pur)For, all batches were synthesized following the same procedure in a batch reactor. Nacure was purified using ion exchange resin (Dowex, strong base anion exchanger). Purified Nacure (82.926 g, 0.09 mol) and water (200 ml) were added to a 500 ml reaction tube. The mixture was cooled to 0° C. (Tj). After 60 minutes, aniline (5.59 g, 0.06 mol) was added to the mixture. After 10 minutes, ammonium persulfate (16.885 g, 0.074 mol) in water (50 ml) was added dropwise over 30 minutes. Once the reaction was complete, toluene was added to the product and the material was washed with 0.01 M H2SO4 (once) and water (three times). To ensure all water was removed, the material was rotary evaporated (three times). A summary of all reactions can be seen in Table 1 below. The conductivity and molecular weight can be seen in Table 2. Table 1 :All refined batches of PANI / DNNSA TIFF0007644570000005.tif72170 Table 2 : Film conductivity and molecular weight TIFF0007644570000006.tif66170

[0102] Thermal stability of neat films Thermal stability testing was performed on neat PANI samples from Boron Molecula. Samples were spin cast onto glass and the resistance was measured. Samples were placed in an oven at temperatures of 70°C, 100°C, and 130°C for 24 hours each. The samples were removed and allowed to cool to room temperature before resistance measurements were made. After 1 hour at room temperature, a second resistance measurement was made to ensure there were no further changes before returning the samples to each temperature for 24 hours.

[0103] Molecular weight characterization method:Gel permeation chromatography (GPC) was used to characterize the molecular weight of polyaniline (PANI). Ammonium formate (AF) 0.02M in N-methylpyrrolidinone (NMP) was used as the mobile phase. The molecular weight distribution was measured using a universal calibration technique with a viscometer and a refractive index detector. All solutions were filtered through a 0.45 micron filter before use. PANI samples were precipitated with spectroquality methanol, washed four times with methanol, and recovered using vacuum filtration. These samples were air-dried, dissolved in AF-MNPs, passed through a 0.2 micron filter, and delivered directly to a GPC vial for analysis. Conventional molecular weights (IR MW) were determined by combining a universal calibration relationship with a column calibration performed with a series of monodisperse polystyrene (PS) standards.

[0104] Batch Processing Comparison :Nacure and Kpure 1.5:1.0 dopant to aniline ratio. FIG. 7A is a graph showing gel permeation results (refractive index vs. retention volume (mL)) using a refractive index detector for polyaniline. Polyaniline was produced using a conventional DNNSA (line 700) or a DNNSA with less than 1 wt. % hydrocarbon content (line 702). The Y-axis shows millivolts. FIG. 7B is a graph showing gel permeation results (viscometer differential pressure vs. retention volume (mL)) using a viscometer for polyaniline. Polyaniline was produced using a conventional DNNSA (line 704) or a DNNSA with less than 1 wt. % hydrocarbon content (line 706). The Y-axis shows millivolts.

[0105] Results using universal calibration TIFF0007644570000007.tif93170

[0106] Thermal Stability Data Procedure: PANI samples were spin coated onto glass slides and dried at 70°C. Silver bars were applied to the edges for electrical contact. Samples were exposed to temperatures of 25°C, 70°C, 100°C, 130°C, 160°C, and 190°C for 24 hours in a convection oven. Resistance was measured for each exposure. FIG. 8 is a graph showing thermal stability data (resistance vs. temperature) of polyaniline, according to one or more embodiments. Lot F series (Lot F1.54, Lot F1.62, Lot F1.81, MAF Lot F) are samples with samples formed using purified DNNSA. 1801, 1802, 1803, and 1804 are samples formed using unpurified NACURE.

[0107] 9 is a graph showing thermal stability data (resistance vs. temperature) of polyaniline according to one or more embodiments. Lines 1702, 1703, 1704, and MAF-2-125-1 are samples formed using unpurified NACURE. Samples 1702, 1703, and 1704 were formed using flow processing. MAF-2-125-1 was formed using batch processing. TIFF0007644570000008.tif102170

[0108] Sample preparation: coating of glass slides. Drop cast: NACURE 1051; KPURE CXC1304. Washed with copious amounts of tap deionized water. Slides were dried at 70° C. for 1 hour. FTIR spectra were generated for the above samples as well as neat NACURE and KPURE. FIG. 10a is an overlaid FTIR spectrum of DNNSA, according to one or more embodiments. KPURE (line 1000) showed no water-insoluble residues detected. Neat KPURE is shown by line 1002. FIG. 10b is an overlaid FTIR spectrum of DNNSA, according to one or more embodiments. NACURE 1051 (line 1004) showed no water-insoluble residues detected. Neat NACURE 1051 is shown by line 1006.

[0109] Conclusions NACURE leaves behind a very sticky water insoluble residue. The sticky material is believed to be aromatic hydrocarbons that are not sulfonated. The residue is an unwanted impurity. KPURE leaves behind no residue, indicating all hydrocarbons are fully sulfonated. Supports low outgassing results under high vacuum.

[0110] Outgassing of PANI-DNNSA using purified DNNSA(F) TIFF0007644570000009.tif107170

[0111] Overall, the present disclosure provides polyaniline and a method for forming polyaniline. The polyaniline of the present disclosure can be substantially free of by-products such as non-sulfonated hydrocarbons, which results in reduced "outgassing" of the polyaniline compared to conventional polyanilines. The reduced outgassing and improved molecular weight properties of the polyaniline of the present disclosure result in improved thermal stability compared to conventional polyanilines. The method of the present disclosure includes forming polyaniline by using aniline and an alkyl-substituted aryl sulfonic acid (e.g., dinonylnaphthalene sulfonic acid (DNNSA)). The alkyl-substituted aryl sulfonic acid of the method of the present disclosure can have a non-sulfonated hydrocarbon content of 1% by weight or less. For example, using a DNNSA having a non-sulfonated hydrocarbon content of 1% by weight or less can provide polyaniline with reduced outgassing and improved thermal stability.

[0112] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. Moreover, while the foregoing is directed to vehicle components in the aerospace industry, for example, embodiments of the present disclosure may be directed to other non-aviation related applications, such as applications in the automotive industry, the maritime industry, the energy industry, wind turbines, satellites, etc.

[0113] The description of various embodiments of the present disclosure has been presented for illustrative purposes, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein have been selected to best explain the principles of the embodiments, practical applications, or technical improvements to the technology found in the market, or to enable others skilled in the art to understand the embodiments disclosed herein. The foregoing is directed to embodiments of the present disclosure, but other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof.

Claims

1. a molecular weight distribution (Mw / Mn) determined by gel permeation chromatography of 1 to 5; Formula (I): is represented by In the formula, R １ , R ２ , R ３ , and R ４ Each instance of is independently selected from hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxyl, and halogen; １ , R ２ , R ３ , and R ４ one or more instances of are optionally replaced with a group independently selected from C1-C20 alkoxyl, and halogen; A － each example of is a sulfonate; A polyaniline, wherein n is an integer such that the polyaniline has a weight average molecular weight (Mw) of 55,000 g / mol to 80,000 g / mol.

2. 2. The polyaniline of claim 1, wherein the polyaniline is hydrocarbon-free.

3. 3. The polyaniline of claim 1 or 2, wherein the polyaniline is an acidified polyaniline having multiple conjugated base counterions.

4. 4. The polyaniline of claim 1, wherein the polyaniline has a number average molecular weight (Mn) of 55,000 g / mol to 74,000 g / mol as determined by gel permeation chromatography.

5. 5. The polyaniline of claim 1, wherein the polyaniline has a Z-average molecular weight (Mz) of from 100,000 g / mol to 250,000 g / mol as determined by gel permeation chromatography.

6. 6. The polyaniline of claim 1, wherein the polyaniline has a Mw of from 65,000 g / mol to 70,000 g / mol.

7. R １ , R ２ , R ３ , and R ４ 2. The polyaniline of claim 1, wherein each instance of is independently selected from hydrogen and unsubstituted C1-C20 alkyl.

8. A － 2. The polyaniline of claim 1, wherein each instance of is dinonylnaphthalene sulfonate.

9. 9. A membrane comprising the polyaniline of any one of claims 1 to 8, the membrane having a hydrocarbon content of 1 wt. % or less, based on the total weight of the membrane.

10. The membrane of claim 9 , wherein the hydrocarbon is naphthalene.

11. introducing an emulsion of aniline in an aqueous solution and an organic solvent solution of an alkyl-substituted aryl sulfonic acid having a hydrocarbon content of 1% or less by weight into a flow reactor having a length of tubing having an inner diameter; polymerizing the monomer within the tube to form polyaniline; A method for producing polyaniline, comprising:

12. 12. The method of claim 11 further comprising introducing a catalyst into the emulsion.

13. 13. The method of claim 11 or 12, further comprising introducing a catalyst into the flow reactor.

14. 14. The method of claim 12 or 13, wherein the catalyst is ammonium persulfate.

15. 15. The method of any one of claims 11 to 14, wherein the alkyl substituted aryl sulfonic acid is dinonyl naphthyl sulfonic acid.

16. 16. The method of any one of claims 11 to 15, wherein the polyaniline has a Mw of 50,000 g / mol to 150,000 g / mol as determined by gel permeation chromatography.

17. 17. The method of any one of claims 11 to 16, wherein the polyaniline has a Mw / Mn of from 1.5 to 1.9 as determined by gel permeation chromatography.

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