Patent Description:
Despite these advances, using current methods there are limitations to the expanded use of conductive polymers. For example, polyaniline (PANI or "emeraldine") is one such conductive polymer that, due to high manufacturing costs, material inconsistencies and batch processing difficulties, is not fully exploited. PANI is widely used in printed board manufacturing as a final finish; protecting the copper and soldered circuits from corrosion. PANI is commonly prepared by chemical oxidative polymerization of aniline in an aqueous solution. Material obtained by this approach is amorphous and insoluble in most organic solvents. PANI reaction times are relatively long (e.g., many hours). Many of the current flow reactors under evaluation use microfluidic chips or miniaturized columns and specialized equipment for control of the flow devices that adds cost and complexity to the process.

<NPL>, relates to a method for the fabrication of monodispersed PANI microspheres through chemical oxidation in a T-junction microfluidic device. A dispersed phase, comprising ammonium persulphate, hydrochloric acid and water, is mixed with a continuous phase, comprising aniline, to fabricate the emeraldine salt form of the polyaniline.

<CIT> relates to an emulsion-polymerization process and electrically-conductive polyaniline salts. The process comprises the steps of combining water, a water soluble organic solvent, a hydrophobic organic acid, an aniline monomer, and a radical initiator and allowing the mixture to form the electrically-conductive polyaniline salt of the acid.

The present invention provides a method comprising: forming an emulsion of aniline and an organic sulfonic acid; introducing the emulsion into a flow reactor, the flow reactor comprising a length of fluoropolymer tubing of inner diameter between <NUM> to <NUM> micrometers; introducing an oxidant to the emulsion or the flow reactor; polymerizing the aniline in the inner diameter of the length of tubing and forming an acid salt thereof, wherein the acid salt of the polymerized aniline is polyaniline dinonylnaphthalene sulfonic acid salt (PANI-DNNSA) and is contained in the length of tubing; and recovering the acid salt of the polymerized aniline from the length of tubing with organic solvent; and wherein the majority of the acid salt of the polymerized aniline deposits on the walls of the length of tubing.

Further advantages of the present disclosure are apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale, wherein like reference numbers indicate like elements throughout the several views.

A preparation of polyaniline-dinonylnaphthalene sulfonic acid (DNNSA) (hereinafter also referred to as "PANI-DNNSA") as a solvent-soluble polymer by flow reactor chemical processing is disclosed herein. The disclosed system and methods provide unique processing sequences for direct collection of the purified emeraldine salt without post reactor manipulation. The present systems and methods provide improvement over known methods of synthesizing conductive polymers, and in particular the conductive polymer salts PANI-DNNSA using very short reaction times not otherwise obtainable using conventional methods, which require long reaction times.

The present systems and methods provides improvement in the efficient and controlled synthesis of polyaniline (PANI) salt as a soluble, intrinsically conductive polymer. A continuous flow synthesis of PANI dinonylnaphthalene sulfonic acid salt (PANI-DNNSA) or "emeraldine salt" is herein described using a flow reactor. In some examples, the flow reactor comprises a microfluidic (<NUM> to about <NUM> I. ) tube reactor. The microfluidic tube is a fluoropolymer, e.g., TEFLON®. The tube reactor provides a suitable surface for deposition of the forming polymer and a straightforward purification of the conductive polymer salt.

As used herein, the phrase "flow reactor" is inclusive of a micro-flow reactor. A micro-flow reactor is used herein as a flow reactor having flow dimensions, e.g., tubing inner diameter (I. ), less than <NUM> (<NUM> microns).

As further described below, as the polymerization reaction preceded, the majority of the polymer product deposits on the walls of the tubing. The polymeric product can be purified by washing with water to remove aqueous soluble reactants, reagents, and side products.

The conductive polymer salts formed in the flow reactor and deposited on the walls of the tubing are eluted with organic solvent to provide soluble conductive polymer salt suitable for solid casting, film forming, or precipitation. The method provides for the preparation of conductive polymer salts having a ratio of conductive polymer monomer to salt of about <NUM>:<NUM> to about <NUM>:<NUM>. The apparatus is configurable for in-situ characterization e.g., by UV-Vis spectroscopy, infrared, and/or mass spectroscopy.

An apparatus and related methods for polymerizing at least one reactant are described. In certain examples, the apparatus is a microfluidic apparatus comprising a mixing chamber and microchannel. In addition, the reactor can further comprise an output chamber and a detection unit that is operatively connected to the microchannel.

With reference to <FIG>, flow reactor system <NUM> shown. First reactant <NUM> and second reactant <NUM> are introduced to first mixing unit <NUM>. The reactor system <NUM> shown in <FIG> can produce conductive polymer salts (mass/per unit time) more efficiently than conventional macroscale devices or batch reactors. Flow reactor <NUM> is capable of operating at a range of processing temperatures from room temperature to about <NUM>° C. , and most advantageously at process temperatures less than <NUM>° C. Room temperature is inclusive of at least above the freezing point of water to less than the boiling point of water. In some examples, ambient temperature is between about <NUM> °F (<NUM> °C) to about <NUM> °F (<NUM> °C). In some examples reactants <NUM>, <NUM> are introduced, independently, to the first mixing unit <NUM> at a predetermined flow rate and/or predetermined concentration such that a desired molar ratio of reactants <NUM>, <NUM> are mixed prior to being introduced to the flow reactor. In other examples, reactants <NUM>, <NUM> are introduced together to the first mixing unit <NUM> such that a desired molar ratio of reactants <NUM>, <NUM> are mixed prior to being introduced to the flow reactor. First mixing unit <NUM> can be any conventional mixing device. In some examples, the mixing device is a high-speed or ultrahigh
speed mixing device capable of emulsifying one or more solutions, for example an aqueous solution and a non-aqueous solution. In some examples, first reactant <NUM> is contained in an aqueous solution and second reactant <NUM> is contained in a non-aqueous solution, whereas first mixing unit <NUM> is designed for emulsifying first reactant <NUM> and second reactant <NUM>. Third reactant <NUM> joins first and second reactants in second mixing unit <NUM>. In some examples, reactant <NUM> is a catalyst. After mixing and second mixing unit <NUM>, reactants are introduced to tubing <NUM> via inlet port <NUM>. Tubing <NUM> comprises discharge port <NUM>, which can be monitored by analysis equipment <NUM>. Analysis equipment <NUM> can include spectroscopic equipment to interrogate and analyze materials flowing from discharge port <NUM>, such as unreacted materials and/or reaction products. Spectroscopic equipment includes UV-Vis, IR (near-, mid-, and far-IR), and mass spectroscopy. Other analytical and interrogating techniques can be used, such as capacitance, pH. Pressure regulating unit <NUM> can be positioned at the outlet of flow reactor <NUM> for monitoring a change in pressure during polymerization or during the collection step of polymerized material and information from pressure regulating unit <NUM> can be used by a controller to cease introduction of the monomer to the flow reactor. An additional pressure regulating unit <NUM> can also be positioned at the inlet of flow reactor <NUM> for example, for monitoring changes in pressure during the process. Fluid lines <NUM> can be independently fluidically coupled to flow reactor <NUM> so as to introduce purging media <NUM> (e.g., water) or collecting medium <NUM> (e.g., solvent) for collecting polymerization product from flow reactor units <NUM>.

In some examples, flow reactor system <NUM> has a single inlet port to the tubing <NUM>. In other examples, flow reactor system <NUM> has additional inlet ports positioned between inlet port <NUM> and discharge port <NUM>. As shown in <FIG>, tubing <NUM> can be coiled around to provide an extended tubular flow reactor.

In some examples, tubing <NUM> is contained in housing <NUM> that provides temperature control and/or support and/or protection from damage of the tubing <NUM>. In some examples, housing <NUM> has an inside surface surrounding at least a portion of the tubing <NUM> such that the coiled tubing <NUM> is at least partially contained within the housing <NUM>. In some examples, housing <NUM> is configured to provide temperature control to the tubing <NUM>, which includes heating and/or cooling.

As shown in <FIG>, alternate flow reactor configuration 100a is shown with plurality of tubing 70a, 70b arranged in a coil configuration coupled in series. Tubing 70a, 70b can be dimensionally the same or can have different lengths and/or different inner diameters. In this configuration, the housing can be bifurcated into separate, sections 40a, 40b receiving tubing 70a, and 70b that can be independently manipulated for heating and/or cooling the tubing. Alternatively, flow reactor configuration 100a can have a single housing receiving tubing 70a, 70b. In contrast to a parallel array configuration of the tubing, where the process stream is split prior to entering the flow reactor, the series array maximizes the amount of time that the reaction mixture is maintained in a diffusion-limiting condition. While not to be held by any particular theory, it is believed that maintaining the reaction mixture in a diffusion limiting condition provides improvement of the presently disclosed reactions for producing conductive polymer salts from reactants in emulsion compared to batch processing. The present methods and systems disclosed herein provide for such a diffusion limiting condition for the emulsion of reactants.

With reference to <FIG>, 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, independently, can be isolated via flow control valves <NUM> situated at the inlet and outlet of each flow reactor introduction of monomer solution to the corresponding flow reactor. Flow control valves <NUM> can be manually operated and/or solenoid-based configured for computer-control using conventional controlling devices. Flow control valves <NUM> can contain one or more check valves for preventing backflow of dispersion solution. One or more pressure regulating units <NUM> can be positioned at the outlet of one or more of the flow reactors for monitoring a change in pressure during polymerization or during the collection step of polymerized material. Additional pressure regulating units <NUM> can also be positioned at the inlet of each flow reactor. Flow control valves <NUM> can be coupled to pressure data from the controller so as to isolate one or more of the flow reactors 70c, 70d, and 70e, for activating purge and/or polymer recovery. In this configuration, flow reactor system 100b can be continuously operated by selectively isolating one or more flow reactor units 70c, 70d, and 70e for collecting polymerization product and/or maintenance while maintaining monomer introduction to one or more of the remaining flow reactor units. Alternatively, flow reactor system 100b can be semi-continuously operated, for example by temporarily ceasing the introduction of monomer to one or more of the flow reactor units 70c, 70d, and 70e. Additional fluid lines <NUM> can be
independently fluidically coupled to one or more of the flow control valves <NUM> so as to introduce purging media <NUM> (e.g., water) or collecting medium <NUM> (e.g., solvent) for collecting polymerization product selectively from one or more flow reactor units 70c, 70d, and 70e. One or more of flow reactor units 70c, 70d, and 70e can be physically removed from flow reactor system 100b for transport with or without polymerization product recovered from in the inner diameter of the tubing.

With reference now to <FIG>, alternate flow reactor configurations are shown. Thus, system 100b has a linear tubing <NUM> arrangement. <FIG> shows system 100c that includes pumping equipment <NUM>, <NUM>, <NUM> for introducing reactants <NUM>, <NUM>, and <NUM> mixing units <NUM>, <NUM>. Pumping equipment can include, for example, syringe pumps, rotary valve pumps and displacement pumps.

With reference to <FIG>, in some examples, tubing <NUM> is coiled or wound as shown on or about the surface of temperature control member <NUM>. Temperature control member <NUM> is of a length L separated by member <NUM>, which can be a cylinder, between members 75a, 75b of height H for providing the predetermined length of tubing and/or support and/or heating/cooling. In some examples, tubing <NUM> is coiled or wound substantially about the surface of temperature control member <NUM>. The longitudinal axis of the surface of temperature control member <NUM> (as shown by line B-B) is substantially perpendicular to the turns of the tubing <NUM>. In some examples, for a large temperature control member composed of a metal block with resistance heating, the system can be configured to allow heat to enter from the block (inner side of the coiled or wound tubing) and at least partially exit through convection through the outside against the environment. For configurations of the flow reactor system <NUM> that may require the reactor to be run with cooling, a complete immersion of the reactor tubing in housing <NUM> can be provided. In other examples, tubing <NUM> is not wound coils but some other arrangement configured for heat management from all sides of the tubing, not just one side or face. Temperature control member <NUM> can be configured for cooling medium or for receiving an electrical resistance heating or other forms of heat that can be controlled by one or more processors configured to a control unit. In some examples, coiled tubing <NUM> is essentially the same interior diameter throughout the coiled section. In other examples the interior diameter of coiled tubing <NUM> varies from inlet port <NUM> to discharge port <NUM>.

In some examples, housing <NUM> is used in combination with temperature control member <NUM>. The housing can be constructed of metal, ceramic, or plastic and may include one or more of heating elements, cooling elements, temperature sensors, and pressure sensors. Tubing <NUM> can be encompassed by housing <NUM> to provide support and/or protection. In some examples, the flow reactor system <NUM> is a microfluidic reactor. In some examples, reactor system <NUM>, comprises microfluidic tubing <NUM>, such as tubing with an inner diameter of less than about <NUM> microns, less than about <NUM> microns, or less than about <NUM> microns to a minimum diameter of about <NUM> microns, coiled or wound into a coil about an outer surface of temperature control member <NUM>. In some examples, the turns of the tubing <NUM> are very closely spaced with one another. In some examples, the distance, independently, between one or more turns of the tubing <NUM> is between about zero (<NUM>) and <NUM> microns. In some examples, turns do not result in the touching of the tubing. In other examples, turns of the tubing result in restricting or preventing airflow between the turns of the tubing for improving heat management.

In other examples, housing <NUM> is a climate controlled environment configured for heating and/or cooling of the tubing. In such a configuration, spacing between turns of the tubing <NUM> can be used to facilitate heat management. Heat management configurations of the housing <NUM> in combination with the tubing <NUM> can comprise the use of either liquid, solid, or gas.

With reference to <FIG>, process flow <NUM> is depicted as exemplary of the methods disclosed herein. Thus preparing an emulsion of aqueous monomer and a salt in a non-aqueous solvent is depicted in Step <NUM>. Introducing the emulsion and a catalyst to the micro reactor tubing is depicted in Step <NUM>. After predetermined time, flow of one or more of the reactants can be terminated and optionally, flushing of the micro reactor tubing with water can be performed as shown in Step <NUM>. Step <NUM> can be performed so as to remove unreacted reactants and/or low molecular weight products. Recovering polymer from the micro reactor tubing with organic solvent is performed in Step <NUM>.

With regard to <FIG>, a sectional view of the tubing <NUM> with internal surface <NUM> of tube bore having an internal diameter D. in some examples outside the scope of the claims, a maximum diameter is less than the diameter at which advantages of diffusion-limited reaction diminishes. This maximum diameter can be as much as <NUM> microns, similar to tubing diameter used for high pressure tubing. In other examples outside the scope of the claims, optimal results may be obtained using diameters less than <NUM> microns or less than <NUM> microns.

According to the claims, the tubing has an inner diameter between <NUM> to <NUM> micrometers. While not to be held to any particular theory, it is believed that faster reaction rates for the reactions disclosed and described herein occur with decreasing reactor tubing inner diameter dimensions, as much as <NUM><NUM> to <NUM><NUM> in microfluidic systems as previously reported with some trade-off of reaction volume per unit time. |The tubing <NUM> is fluoropolymer tubing.

Tubing length can be chosen based on the ability of the selected components of the system (pump, tubing burst strength, fittings) to handle pressure. The maximum length of tubing 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 tubing. In some examples, the system can be configured to operate at a tubing length coupled with a tubing inner diameter such that the system operates at or below about <NUM> bar (<NUM> MPa). In other examples, the tubing <NUM> is tubing of diameter less than <NUM> microns (microfluidic tubing) with a length of about <NUM> meters or less. Other combinations of tubing diameter and to be length can be used commensurate with the operating parameters of the system and the desired reaction volume per unit time.

The cross-section of the tubing may be any shape, but preferably is circular. In some examples, polymerization occurs on internal surface <NUM> of tube bore as shown in <FIG> where polymerization product <NUM> restricts the internal diameter D to a reduced diameter D'. In some examples, the tubing inner diameter or the reduction in internal diameter D is symmetrical about longitudinal axes A-A, B-B. In some examples, the tubing inner diameter or the reduction in internal diameter D is non-symmetrical about longitudinal axes A-A, B-B. This reduction in diameter D to diameter D' of the tubing <NUM> causes a back pressure that can be measured and/or used in part to control the process herein.

As shown in <FIG>, this back pressure can be monitored whereas at the beginning of polymerization back pressure <NUM> at time T1 is consistent with the viscosity and flow rate of the emulsified reactant mixture being fed into tubing <NUM>. During a time period T2, where polymerization has caused a reduction in the internal diameter of tubing <NUM>, the back pressure begins to increase and approaches a threshold <NUM>. In some examples the system is designed to terminate polymerization when the back pressure value <NUM> reaches the predetermined threshold <NUM>. The rate of change of the back pressure as depicted in time period T2 can be adjusted taking into account the burst strength of the capillary tubing and other reactor parameters by manipulation of the viscosity of the reactants, the molar concentration of the reactants and/or catalyst, temperature, flow rates and combinations thereof. <FIG> depicts a process flow diagram <NUM> that represents an example of the presently disclosed method. Thus, pumping reactant emulsion and catalyst into the micro reactor tubing is depicted by Step <NUM>. Monitoring back pressure of the reactant emulsion during the polymerization process is depicted in Step <NUM>. Using conventional pressure monitoring equipment either external or electrical with the pumping devices is envisioned. Introduction of the reactant emulsion is terminated once the threshold back pressure is reached as depicted in Step <NUM>. Recovering the product polymer from the micro reactor tubing by flushing with organic solvent is depicted in Step <NUM>.

The method disclosed herein is applied to the manufacture of conjugated conductive polymer polyaniline-dinonylnaphthalene sulfonic acid salt ("PANI-DNNSA"), which is a conductive polymer for electronic applications such as organic light-emitting diodes (OLED), solar cells, semiconductors, display screens and chemical sensors.

Thus, a continuous flow synthesis process of PANI-DNNSA salt is provided. The flow apparatus was designed to allow addition of the oxidative reagent to a preformed emulsion of aqueous aniline and the organic soluble DNNSA. Our first test case evaluates the emulsion polymerization of equimolar amounts of aniline and DNNSA in the presence of ammonium persulfate as the oxidative catalyst. The reaction is depicted below in Equation (<NUM>):
<CHM>.

Thus, with reference to <FIG>, process flow diagram <NUM> is shown. Steps <NUM> and <NUM> introduce an aqueous composition comprising aniline and a non-aqueous composition comprising dinonylnaphthalene sulfonic acid (DNNSA), respectively into a first mixer. Forming a reactant emulsion in the first mixer is performed in Step <NUM>. Introducing a catalyst and the reactant emulsion into a second mixer is performed in Step <NUM>. Introducing to the micro reactor tubing and obtaining a threshold back pressure is performed in Step <NUM>. Terminating introduction of reactant emulsion and catalyst to micro reactor tubing is performed in step <NUM>. Optionally, the micro reactor tubing can be flushed with water in Step <NUM> to remove unreacted material and/or low molecular weight polymer. Recovering polyaniline polymer salt from micro reactor tubing with organic solvent is carried out in Step <NUM>.

Dinonylnaphthalene sulfonic acid (DNNSA) was obtained from King Industries (Norwalk, CT, USA) as a <NUM>% w/w solution in n-butylglycol. The UV-Vis spectra were collected using a Hitachi U-<NUM> spectrometer. A film of the sample was prepared by drying a xylene solution in a quartz cuvette overnight and subsequent drying in vacuo. The cuvettes were placed on the side to allow for a consistent film to form over the quartz glass. Impurity profiles of the PANI:DNNSA samples were analyzed by reverse phase High Performance Liquid Chromatography (HPLC) to check for residual starting materials and solvents.

Flow Equipment. A tubular flow reactor coil was prepared from <NUM>/<NUM>" (<NUM>) O. X <NUM>" (<NUM>) I. TEFLON° tubing of approximately <NUM> (<NUM> ft) in Length. The tubing was wrapped around an aluminum spool <NUM>" (<NUM>) in diameter with a height of <NUM>" (<NUM>). These dimensions for the spool allow for a single layer of <NUM> turns of the TEFLON° tubing. A calculated volume of the 'TEFLON° flow reactor was <NUM> based on the dimensions.

Measured volume including dead volume before and after the reactor coil was <NUM>. The assembled TEFLON° flow reactor was fitted to a custom built aluminum spindle fitted with a 120V Firewire heater. Temperature control was achieved with a Model <NUM> J-KEM temperature controller (J-KEM Scientific, Inc. Louis, MO) attached to a K-type thermocouple and the heating unit in the aluminum block. Reagents were introduced into the reactor coil by the use of three separated syringe pumps equipped with plastic or glass syringes. Two KD Scientific (K-<NUM> and K-<NUM>) and a Sage (Model #<NUM>) syringe pumps were employed. The first mixer for combining solutions of aniline and DNNSA consisted of a modified Rainin HPLC mixer unit with a magnetically driven TEFLON° stirrer in a stainless steel cylinder. Introduction of the oxidation catalyst ammonium persulfate was carried out with a standard HPLC T-fitting (SS, <NUM>" (<NUM>) I. Collection of fractions from the reactor coil was achieved either by manually changing fractions or with a Gilson <NUM> fraction collector. Components of the flow system were connected with standard <NUM>/<NUM>" (<NUM>) TEFLON° tubing and HPLC grade fittings of either stainless steel or polyetheretherketone (PEEK).

Synthesis of Polyaniline-dinonylnaphthalene sulfonic acid (<NUM> mmol scale). The flow system herein described as in <FIG>, was equilibrated with water from all three syringes at a total initial flow rate of <NUM>/min to dislodge any air or bubbles in the flow reactor coil. The temperature of the coil was maintained at <NUM> °C throughout the process. Once the air was displaced from the system, the syringes in each of the pumps were exchanged with the appropriate reagent. Syringe pump A (Sage pump) was fitted with a <NUM> plastic syringe containing a freshly prepared solution of <NUM> aniline in distilled, deionized water. The KD Scientific pumps B and C were equipped with <NUM> of <NUM> DNNSA in n-butylglycol in a <NUM> plastic syringe and <NUM> of <NUM> ammonium persulfate in a <NUM> plastic syringe, respectively.

Based on the above volumes of material introduced into the reactor coil, the reaction scale was designated as a <NUM> mmole scale. Pumps A (aniline: <NUM>/min) and B (DNNSA: <NUM>/min) were initiated to start formation of the aniline-DNNSA emulsion. Once the white emulsion reached with second T-mixer, pump C (oxidant: <NUM>/min) was started for initiation of the reaction. After a period of time the flow rate was observed to rapidly decline due to increasing back pressure in the system. It was observed in this example that the first <NUM> that exited from the reactor coil contained a heterogeneous mixture of the PANI polymer in the organic phase and some aqueous phase byproducts. This initial fraction was extracted with xylene and the extract washed twice with water. The dried organic layer of this solvent extract was concentrated in vacuo to afford <NUM> of a blue-green film (UV-Vis spectra <NUM> in <FIG>). UV-Vis (dried film) <NUM>, <NUM>, <NUM>, <NUM>; Elemental Analysis: C, <NUM>; H, <NUM>; N, <NUM>; S, <NUM>. After a total of about <NUM>, flow from pump A was stopped. In one example, the reagent syringes were replaced with syringes containing water to terminate the polymerization in the flow reactor.

In this example, after polymerization was terminated, the flow reactor was flushed with an amount of water to remove any water soluble reactants or by-products. No PANI products were collected from this water flush and the significant blue color remained in the flow reactor tubing. Following this water flush, the reactor was then flushed with an amount of xylene and the wash collected gave a concentrated blue extract. The solvent extract was dried and concentrated in vacuo to afford <NUM> of a blue-green film. UV-Vis (dried film) <NUM>, <NUM>, <NUM>, <NUM>, is shown in <FIG> as spectra <NUM>. Elemental Analysis: C, <NUM>; H, <NUM>; N, <NUM>; S, <NUM>.

Synthesis of Polyaniline-dinonylnaphthalene sulfonic acid (<NUM> mmol scale). The flow reactor system was setup as described for the previous <NUM> mmole scale reaction, however the positions of the pumps and size of the syringes were changed to overcome the initial backpressure from formation and deposition of polymeric material in the flow reactor. Using smaller syringes, the pumps were outfitted as follows: Pump A: <NUM> syringe of <NUM> aniline, KD Scientific pump; Pump B: <NUM> syringe of <NUM> DNNSA solution, KD Scientific pump. Pump C: <NUM> syringe of <NUM> (NH4)2S208, Sage pump. Samples were collected in <NUM> fractions. The initial heterogeneous fractions were worked up as described previously to yield <NUM> of a blue-green residue. UV-Vis (dried film) <NUM>, <NUM>, <NUM>; Elemental Analysis: C, <NUM>; H, <NUM>; N, <NUM>; S, <NUM>.

After collection of the initial fraction, the flow reactor tubing was washed with water using an HPLC pump. Initial measured backpressure for the water wash was <NUM> psi (<NUM> MPa). The reactor was then flushed with <NUM> of xylene. Once the xylene had displaced water in the reactor coil, the backpressure dropped to less than <NUM> psi (<NUM> kPa). The xylene flush afforded a major fraction of product; <NUM> of a blue-green residue. UV-Vis (dried film) <NUM>, <NUM>, <NUM>; Elemental Analysis: C, <NUM>; H, <NUM>; N, <NUM>; S, <NUM>. Total yield from the <NUM> mmole scale reaction based on <NUM>:<NUM> stoichiometry of PANI:DNNSA was <NUM> (<NUM>%).

Current flow reactors, including micro-reactors, use microfluidic chips or miniaturized columns and specialized equipment for control of the flow devices. The present system and method provides a device that can be assembled from syringe pumps, commercially available HPLC tubing and an aluminum holder outfitted with a standard thermocouple temperature control device. By using syringe pumps to control the flow of reagents, the pressure in the reactor can be held well below the limits of the flow reactor tubing and low pressure fittings. Concentrations and flow rates of reagents can be chosen to provide an overall reaction concentration similar to that used in batch processing. For example, for PANI-DNNSA, the overall reaction concentration after mixing can be <NUM>, which is very close to the value calculated for previously published batch reactions.

While stoichiometry of the reagents used in the present disclosure was approximately one equivalent each of aniline, DNNSA and ammonium persulfate, other stoichiometry can be used. For PANI, monomer concentration was limited by the solubility of aniline in water, which at room temperature is slightly greater than <NUM>. Thus, for the exemplary experiment using PANI, Pump A was charged with the <NUM> aniline solution and delivered at <NUM>/min and
the DNNSA solution, approximately <NUM>% w/w in n-butylglycol or <NUM> solution, was placed in pump Band delivered at <NUM>/min, and Pump C was charged with a freshly prepared <NUM> ammonium persulfate solution delivered at <NUM>/min. Each reagent has a delivery rate of <NUM> mmole per minute resulting in a total flow rate for the reaction mixture of <NUM>/min. Other total flow rates can be used commensurate with the system parameters and polymer product.

It was noted that both the <NUM> mmole scale and the <NUM> mmole scale reaction provided two distinct fractions; an initial fraction was obtained in the biphasic reaction mixture which was purified by the usual extraction route; and a larger scale reaction. The first fraction was a minor component representing <NUM>% of the total material. Unexpectedly, the major fraction adhered to the flow reactor tubing. While it did not completely inhibit flow through the reactor, it did increase the back-pressure of the system. Thus, monitoring of the backpressure was used to facilitate monitoring of the reaction process. Based on these results, it is possible to produce PANI-DNNSA product at rates of grams/day for a given flow reactor unit, for example, <NUM> grams/day, or <NUM> grams/day, up to about <NUM> grams/day, of which production amounts can be multiplied by the number of parallel flow reactors used. Thus, the present disclosure provides for a method of producing large quantities of compositionally consistent conductive polymer salts such as PANI-DNNSA cost effectively and with relatively high yield and high production rates.

In both trials, the reactor coil was washed with water to remove aqueous impurities such as sulfuric acid and excess oxidant catalyst, while the major product was obtained by flushing the flow reactor with xylene. Due to the solubility of the PANI-DNNSA product, it is possible to obtain the product in a minimum amount of xylene. The deposition of the PANI-DNNSA product is an advantageous result, allowing removal of aqueous impurities and direct extraction of the polymer in xylene, for example, without post-reactor workup and to provide a product that is capable of being spun coated or precipitated.

<FIG> depicts a UV-Vis Spectra of PANI:DNNSA as a dried film, where the UV-Vis spectra <NUM> of an early first fraction shows similarity with the UV-Vis spectra <NUM> of major late fraction as products. Expected UV absorptions are seen for an aniline ring and the incorporation of the naphthalene ring in the DNNSA salt. Elemental analysis was obtained and analysis of the mole percent of N and S shows that these elements are present in equal molar amounts, suggesting a one to one ratio of the nitrogen component of PANI and the sulfonic acid of DNNSA or a polymeric material that is <NUM>:<NUM> PANI:DNNSA. Previously reported conductive PANI:DNNSA
polymer was obtained in a <NUM>:<NUM> ratio. The present <NUM>:<NUM> material is believed the result of a slight molar excess of DNNSA used in the process. Manipulation of the PANI:DNNSA ratio is possible with the present system and method and allows for varying the ratio in the finished polymer product.

Claim 1:
A method comprising:
forming an emulsion of aniline and an organic sulfonic acid;
introducing the emulsion into a flow reactor (<NUM>), the flow reactor comprising a length of fluoropolymer tubing (<NUM>) of inner diameter between <NUM> to <NUM> micrometers;
introducing an oxidant to the emulsion or the flow reactor;
polymerizing the aniline in the inner diameter of the length of tubing and forming an acid salt thereof, wherein the acid salt of the polymerized aniline is polyaniline dinonylnaphthalene sulfonic acid salt (PANI-DNNSA) and is contained in the length of tubing; and
recovering the acid salt of the polymerized aniline from the length of tubing with organic solvent; and
wherein the majority of the acid salt of the polymerized aniline deposits on the walls of the length of tubing.