Flow reactor synthesis of polymers

Abstract

A flow reactor system and method for polymerizing multiple monomers is provided, having a tube that serves as a polymerization chamber. The flow reactor has at least one inlet port, at least one mixing chamber, and an outlet port. The method includes providing two phases, an aqueous phase and a non-aqueous phase, and forming an emulsion for introduction into the flow reactor.

Description

[Technical field]

[0001] By appropriately designing their chemical structures, conjugated polymer 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 polymer materials often suffer from high manufacturing costs, material inconsistencies, and processing difficulties when prepared by batch processing. [Background technology]

[0002] Despite these advances, current methods limit the widespread use of conductive polymers. For example, polyaniline (PANI or "emeraldine") is one conductive polymer that has not been fully utilized due to high manufacturing 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 method is amorphous and insoluble in most organic solvents. The reaction time of PANI is relatively long (e.g., over a long period of time). Many of the current flow reactors under evaluation use microfluidic chips or miniaturized columns, as well as specialized equipment for flow device control, which adds cost and complexity to the process. Summary of the Invention

[0003] In a first embodiment, a method is provided that includes forming an emulsion of a monomer and an acid, introducing the emulsion into a flow reactor, the flow reactor comprising a length of tubing having an inner diameter of between about 1 and about 4000 microns, and polymerizing the monomer to form its acid salt.

[0004] In one embodiment, the method further comprises recovering a salt of the polymerized monomer. In another embodiment, alone or in combination with any of the previous embodiments, the method further comprises introducing a catalyst into the emulsion or flow reactor.

[0005] In another embodiment, alone or in combination with any of the preceding embodiments, the emulsion comprises an aqueous solution of the monomer and an organic solvent solution of the acid.

[0006] In another aspect, alone or in combination with any of the preceding aspects, the length of tube is wound.

[0007] In another aspect, alone or in combination with any of the preceding aspects, the polymerized monomer salt is substantially contained within a length of tubing, the tubing being a fluoropolymer. In another aspect, alone or in combination with any of the preceding aspects, the method further comprises removing unreacted material from the tubing using water. In another aspect, alone or in combination with any of the preceding aspects, the method further comprises recovering the polymerized monomer salt from the tubing using an organic solvent.

[0008] In a second embodiment, a method is provided that includes forming an emulsion of aniline and an organic or sulfonic acid; introducing the emulsion into a flow reactor, the flow reactor comprising a length of tubing having an inner diameter between about 1 and about 4000 microns; introducing an oxidant into the emulsion or flow reactor; and polymerizing the aniline within the inner diameter of the length of tubing to form its acid salt.

[0009] In one aspect, the length of tube is wound. In another aspect, alone or in combination with any of the preceding aspects, the polymerized salt of aniline is substantially contained within the length of tube, and the tube is a fluoropolymer.

[0010] In another embodiment, alone or in combination with any of the preceding embodiments, the method further comprises recovering the salt of the polymerized aniline from the tube using an organic solvent.

[0011] In another embodiment, alone or in combination with any of the preceding embodiments, the molar ratio of aniline to organic acid or sulfonic acid is between 1 and 0.2. In another embodiment, alone or in combination with any of the preceding embodiments, the total flow rate of aniline is from about 0.01 mmol / min to about 0.2 mmol / min, resulting in a flow rate of the emulsion reaction mixture into the flow reactor of from 0.1 mL / min to about 0.5 mL / min. In another embodiment, alone or in combination with any of the preceding embodiments, the oxidizing agent is introduced at a flow rate of from about 0.001 to about 0.2 mL / min.

[0012] In a third aspect, a polymerization apparatus for reacting one or more monomers to produce one or more polymers is provided, the polymerization apparatus comprising: a quantity of tubing having an inner diameter between about 1 and about 1000 microns, the tube including at least one inlet port and at least one outlet port, the quantity of tubing having at least one inlet port for receiving a reactant composition and at least one outlet port; a temperature controller sized to receive at least a portion of the tubing; a mixing chamber having an inlet port and an outlet port fluidly connected to the inlet port of the tubing; and at least one fluid flow control device fluidly connected to the inlet port of the mixing chamber.

[0013] In one embodiment, the tubing is wrapped around the temperature controller.

[0014] In another embodiment, alone or in combination with any of the preceding embodiments, the at least one fluid control device comprises a monomer fluid flow control device and an acid fluid flow control device. In another embodiment, alone or in combination with any of the preceding embodiments, the device further comprises a second mixing chamber fluidly connected to the outlet of the mixing chamber and the inlet of the tube. In another embodiment, alone or in combination with any of the preceding embodiments, the device further comprises a catalyst fluid flow control device fluidly connected to the second mixing chamber or the tube. [Brief description of the drawings]

[0015] Further advantages of the present disclosure will become apparent by reference to the detailed description when considered in conjunction with the drawings, which are not to scale and in which like reference numerals refer to like elements throughout the several views.

[0016] [Figure 1A] FIG. 1 is a diagram of an exemplary flow reactor system as disclosed and described herein. [Figure 1B] FIG. 1 is a diagram of an exemplary continuous flow reactor system as disclosed and described herein. [Figure 1C] FIG. 1 is a diagram of an exemplary parallel flow reactor system as disclosed and described herein. [Diagram 2] FIG. 2 is a diagram of another exemplary flow reactor system disclosed herein. [Diagram 3] FIG. 2 is a diagram of another exemplary flow reactor system as disclosed and described herein. [Figure 4] FIG. 1 is a diagram of a spool flow reactor as disclosed and described herein. [Diagram 5] FIG. 1 is a process flow diagram of a polymerization process using the systems and methods disclosed and described herein. [Figure 6] FIG. 2 is a cross-sectional view of the inner diameter region of the flow reactor. [Figure 7] FIG. 1 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. [Figure 8] 1 is a graph illustrating backpressure and reaction time in accordance with the present disclosure. [Figure 9] FIG. 1 is a process flow diagram of a polymerization process using the systems and methods disclosed and described herein. [Figure 10] FIG. 1 is a process flow diagram of a method for polymerization of PANI-DNNSA using the systems and methods disclosed and described herein. [Figure 11] 1 is a UV-Vis spectrum of PANI-DNNSA prepared using the systems and methods disclosed and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Disclosed herein is the preparation of polyaniline-dinonylnaphthalene sulfonic acid (DNNSA) (hereinafter referred to as "PANI-DNNSA") as a solvent-soluble polymer by flow reactor chemical processing. The disclosed system and method provide a unique processing sequence to directly collect purified emeraldine salt without post reactor processing manipulation. The system and method provide an improvement over known methods of synthesizing conductive polymers, specifically conductive polymer salts (e.g., PANI-DNNSA). The system and method provide very short reaction times that cannot be achieved using conventional methods that require long reaction times.

[0018] For example, the present systems and methods provide improvements for efficient and controlled synthesis of polyaniline (PANI) salts as soluble, intrinsically conductive polymers. Continuous flow synthesis of PANI dinonylnaphthalene sulfonic acid salts (PANI-DNNSA) 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 suitable surface for deposition of the polymer being formed and a surface that facilitates direct purification of the conductive polymer salt.

[0019] As used herein, the term "flow reactor" includes microflow reactors, which are used herein as flow reactors having flow surfaces, e.g., tube inner diameters (IDs), less than 1 mm (1000 microns).

[0020] As described further below, in some embodiments, as the polymerization reaction proceeds, a large portion of the polymerization product will deposit on the walls of the tube, and the polymerization can be purified by washing with water to remove water-soluble reactants, reagents, and by-products.

[0021] The conductive polymer salt formed in the flow reactor and deposited on the walls of the tubes can be eluted with an organic solvent to provide a soluble conductive polymer salt suitable for solid casting, film formation, or precipitation. The method provides for the preparation of conductive polymer salts having a ratio of conductive polymer monomer to salt of about 1:1 to about 1:0.2. The apparatus can be configured for in situ characterization, for example, by UV-Vis spectroscopy, infrared, and / or mass spectroscopy.

[0022] 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.

[0023] Referring to FIG. 1A, a flow reactor system 100 is shown. A first reactant 10 and a second reactant 20 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 macro-scale devices or batch reactors. The flow reactor 100 can operate at a processing temperature range of room temperature to about 250° C., and most advantageously below 100° C. Room temperature includes at least a temperature above the freezing point of water to below the boiling point of water. 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 conventional 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, for example, aqueous and non-aqueous solutions. In some embodiments, the first reactant 10 is contained in an aqueous solution and the second reactant 20 is contained 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 includes an outlet port 80 that can be monitored by an analytical device 90. The analytical device 90 may include a spectroscopic device that examines and analyzes the material flowing from the exhaust port 80, such as unreacted material and / or reaction products. Spectroscopic devices include UV-Vis, IR (near, mid, and far infrared), and mass spectrometry. Other analytical and investigative techniques can be used, such as capacitance, pH, etc.A pressure regulation unit 67 may be positioned at the outlet of the flow reactor 70 to monitor pressure changes during the polymerization process or during a step of collecting the polymerized material. Information from the pressure regulation unit 67 may be used by the controller to discontinue introduction of monomer to the flow reactor. Additionally, for example, an additional pressure regulation unit 67 may be positioned at the inlet of the flow reactor 70 to monitor pressure changes during the course of the process. A fluid line 69 may be individually fluidly connected to the flow reactor 70 to introduce a purge medium 66 (e.g., water) or a collection medium 68 (e.g., a solvent) to collect the polymerization product from the flow reactor unit 70.

[0024] In some embodiments, the flow reactor system 100 has a single inlet port for the tube 70. In other embodiments, the flow reactor system 100 has an additional inlet port located between the inlet port 65 and the exhaust port 80. As shown in FIG 1A, the tube 70 may be coiled to provide an expanded tubular flow reactor.

[0025] In some embodiments, tube 70 is contained within a housing 40 that 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.

[0026] 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 continuous 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 the above-mentioned diffusion-limited condition for an emulsion of reactants.

[0027] 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 collection step of the polymerized material. Additional pressure regulation units 67 may be further positioned at the inlet of each flow reactor. The flow control valve 63 may be coupled to pressure data from the controller to isolate one or more of the flow reactors 70c, 70d, and 70e to activate purging and / or polymer recovery. In this configuration, the flow reactor system 100b may be operated continuously by selectively isolating one or more of the flow reactor units 70c, 70d, and 70e for collection of polymerization product and / or maintenance while maintaining introduction of monomer to one or more of the remaining flow reactor units. Alternatively, the flow reactor system 100b may be operated semi-continuously, for example, by temporarily ceasing introduction of monomer to one or more of the 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 to introduce a purge medium 66 (e.g., water) or a collection medium 68 (e.g., a solvent) for selectively collecting 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.

[0028] 2 and 3, alternative flow reactor configurations are shown. Thus, system 100b has a linear tube 70 configuration. In some embodiments, the cross-sections of the tubes 70 in system 100b are rectangular or other shapes, each having a cross-sectional shape of about 100 microns to 4000 microns individually. FIG. 3 shows system 100c, which includes pumping devices 15, 25, 55, and 52 for introducing reactants 10, 20 and mixing units 30, 60. The pumping devices may include syringe pumps, rotary valve pumps, displacement pumps, and the like.

[0029] Referring to FIG. 4, in some embodiments, the tube 70 is wound or wrapped on or around the surface of the temperature control member 75 as shown. The temperature control member 75 has a length L separated by a member 78, which may be a cylinder between members 75a, 75b having a height H, providing a length of tube and / or support and / or heating / cooling. In some embodiments, the tube 70 is substantially wound or wrapped around the surface of the temperature control member 75. The longitudinal axis (shown by line BB) of the surface of the temperature control member 75 is substantially perpendicular to the turns of the tube 70. In some embodiments, for a large temperature control member consisting of a metal block with resistive heating, the system may be configured to allow heat to enter the block (inside the wound or wrapped tube) and be at least partially exhausted to the outside environment through convection. For configurations of the flow reactor system 100 that may require the reactor to operate with cooling, a full recessing of the reactor tube within the housing 40 may be achieved. In other embodiments, the tube 70 is not a wound coil, but some other configuration configured to control heat from all sides of the tube, rather than just one side or surface of the tube. The temperature control member 75 may be configured to cool a medium, or may be configured to receive electrical resistance heating or other forms of heating that can be controlled by one or more processors connected to a control unit. In one aspect, the wound tube 70 has approximately the same inner diameter throughout the wound section. In other aspects, the inner diameter of the wound tube 70 varies from the inlet port 65 to the exhaust port 80.

[0030] In some embodiments, the housing 40 is used in combination with the temperature control member 75. The housing may be made of metal, ceramic, or plastic and may include one or more of a heating element, a cooling element, a temperature sensor, a pressure sensor, and the like. The tube 70 may be surrounded by the housing 40 to provide support and / or protection. In some embodiments, the flow reactor system 100 is a microfluidic reactor. In one aspect, the reactor system 100 includes a microfluidic tube 70. The microfluidic tube 70 is a tube having an inner diameter of less than about 1000 microns, less than about 900 microns, or less than about 800 microns, for example, that is coiled or wrapped around the outer surface of the temperature control member 75. In some embodiments, the turns of the tube 70 are spaced very close to each other. In some embodiments, the individual distances between one or more turns of the tube 70 are between about 0 and 100 microns. In some embodiments, the turns do not cause the tube to touch. In other embodiments, the tube turns restrict or prevent air flow between the tube turns for improved thermal control.

[0031] In other embodiments, the housing 40 is a climate-controlled environment configured to heat and / or cool the tubes. In such configurations, the spacing between the turns of the tubes 70 may be used to facilitate thermal control. The thermal control configuration of the housing 40 in combination with the tubes 70 may include the use of either a liquid, a solid, or a gas.

[0032] Referring to FIG. 5, a process flow 101 is shown as an example of the method disclosed herein. Thus, step 105 shows preparing an emulsion of aqueous monomer and salt in a non-aqueous solvent. Step 110 shows introducing the emulsion and catalyst into a microreactor tube. After a predetermined time, the flow of one or more of the reactants may be stopped, and optionally, washing the microreactor tube with water may be performed, as shown in step 115. Step 115 may be performed to remove unreacted reactants and / or low molecular weight products. Step 120 shows recovering the polymer from the microreactor tube with an organic solvent.

[0033] 6 and 7, a cross section of a tube 70 is shown with the inner surface 71 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 as much as 4000 microns, similar to tube diameters used in high pressure tubing. In other embodiments, optimal results may be obtained with inner 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 faster kinetics of the reactions disclosed and described herein may be achieved by increasing the inner diameter dimension of the reactor tube to less than 10 in microfluidic systems. 4 From 10 6 This is believed to occur when the capillary tube 70 is allowed to shrink to about 1 / 2 the volume of the 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 70 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.

[0034] The tubing length may be selected based on the ability of selected components of the system to handle pressure (pumps, tubing burst strength, fittings, etc.). 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 embodiments, the system may be configured to operate with connected tubing lengths having inner tubing diameters such that the system operates at about 20 bar (280 psi) or less. In some embodiments, the length of the tubing does not exceed 500 meters, with tubing having an inner diameter of less than 4000 microns. In other embodiments, the tube 70 is less than 1000 micron diameter tubing (microfluidic tubing) with a length of about 100 meters or less. Other combinations of tubing diameters and lengths may be used commensurate with the operating parameters of the system and the desired reaction volume per unit time.

[0035] The cross section of the tube may be any shape, preferably circular. In some embodiments, as shown in FIG. 7, polymerization occurs on the inner surface 71 of the tube bore. Polymerization product 73 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 70 to diameter D' creates a back pressure that can be measured and / or used in part to control the processes described herein.

[0036] This back pressure can be monitored as shown in FIG. 8. In the early stages of polymerization, at time T1, the back pressure 400 corresponds to the viscosity and flow rate of the emulsified reaction mixture being fed into the tube 70. During time period T2, as the polymerization reduces the inner diameter of the tube 70, the back pressure begins to increase and approaches a threshold value 450. In some embodiments, the system is designed to stop the polymerization when the back pressure value 420 reaches a predetermined threshold value 450. The rate of change of the back pressure, 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. 9 shows a process flow diagram 200 depicting an embodiment of the presently disclosed method. Thus, step 205 shows pumping the emulsion of reactants and catalyst into the microreactor tube. Step 210 shows monitoring the back pressure of the emulsion of reactants during the polymerization process. It is contemplated that a conventional pressure monitoring device, either external or electrical, with the pumping device may be used. Introduction of the reactant emulsion is stopped once the threshold backpressure is reached, as shown in step 215. Step 220 shows the product polymer being recovered from the microreactor tube by washing with an organic solvent.

[0037] For example, the methods disclosed herein can be applied to the preparation of the conjugated conductive polymer polyaniline-dinonylnaphthalene sulfonic acid salt (PANI-DNNSA), which is a conducting polymer for electrical applications such as organic light-emitting diodes (OLEDs), solar cells, semiconductors, display screens, and chemical sensors.

[0038] Thus, an example of 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. The first test case evaluates the emulsion polymerization of equimolar amounts of aniline and DNNSA in the presence of ammonium persulfate as an oxidation catalyst. The reaction is shown in equation (1) below.

[0039] TIFF0007627713000001.tif47170

[0040] Thus, referring to FIG. 10, a process flow diagram 300 is shown. In steps 302 and 304, an aqueous composition including aniline and a non-aqueous composition including dinonylnaphthalene sulfonic acid (DNNSA) are introduced into a first mixer, respectively. In step 310, an emulsion of reactants is formed in the first mixer. In step 315, an emulsion of catalyst and reactants is introduced into a second mixer. In step 320, an introduction into the microreactor tube and obtaining a threshold back pressure are performed. In step 325, an introduction of the emulsion of reactants and catalyst into the microreactor tube is stopped. Optionally, in step 330, the microreactor tube can be washed with water to remove unreacted materials and / or low molecular weight polymers. In step 335, a polyaniline polymer salt is recovered from the microreactor tube using an organic solvent.

[0041] Experimental Section Dinonylnaphthalenesulfonic acid (DNNSA) was obtained from King Industries (Norwalk, CT, USA) as a 50% w / w aqueous solution in n-butylglycol. UV-Vis spectra were collected using a Hitachi U-3900 spectrometer. Films of the sample were prepared by drying the xylene solution in a quartz cuvette overnight followed by drying in vacuum. The cuvette was placed on its side to allow for consistent film formation on the quartz glass. The impurity profile of the PANI:DNNSA sample was analyzed by reversed-phase high performance liquid chromatography (HPLC) to check for residual starting materials and solvents.

[0042] Flow Apparatus A tubular flow reactor coil was prepared from TEFLON® tubing approximately 21 m (70 ft) long with a 1 / 16" outer diameter and 0.031" inner diameter. The tubing was wrapped around an aluminum spool 4.25" high and 4" in diameter. The dimensions of this spool allow for a single layer of 65 turns of TEFLON® tubing. The calculated volume of the TEFLON® flow reactor was 10.4 mL based on the dimensions. The measured volume, including the dead volume before and after the reactor coil, was 11.4 mL. The assembled TEFLON® flow reactor was fitted to a custom aluminum spindle fitted with a 120V Firewire heater. Temperature control was achieved using a Model 150 J-KEM temperature controller (J-KEM Scientific, Inc., St. Louis, MO, USA) attached to a K-type thermocouple and heating unit within an aluminum block. Reagents were introduced into the reactor coil using three separate syringe pumps equipped with plastic or glass syringes. Two KD Scientific (K-100 and K-250) syringe pumps and a Sage (Model #355) syringe pump were utilized. The first mixer for combining the aniline and DNNSA solutions consisted of a modified Rainin HPLC mixing unit with a magnetically driven TEFLON® stirrer in a stainless steel cylinder. Introduction of the oxidation catalyst, ammonium persulfate, was performed using a standard HPLC T-fitting (SS, 0.040" internal diameter). Collection of fractions from the reactor coil was accomplished by manual fraction changing or using a Gilson 203B fraction collector. The flow system components were connected with standard 1 / 16" TEFLON® tubing and stainless steel or polyetheretherketone (PEEK) HPLC grade fittings.

[0043] Synthesis of Polyaniline-Dinonylnaphthalene Sulfonic Acid (1 millimole scale). The flow system of the present disclosure illustrated in FIG. 3 was equilibrated with water from all three syringes at an initial total flow rate of 0.427 mL / min to remove any air or bubbles in the flow reactor coil. The temperature of the coil was maintained at 25° C. throughout the process. Once the air was removed from the system, the syringes of each pump were replaced with the appropriate reagent. Syringe pump A (Sage pump) was fitted with a 60 mL plastic syringe containing a freshly prepared 0.375 M solution of aniline in distilled deionized water. KD Scientific pumps B and C were equipped with 20 mL of 1.0 M DNNSA in n-butyl glycol in a 20 mL plastic syringe, and 10 mL of 2.0 M ammonium persulfate in a 10 mL plastic syringe, respectively. Based on the above volumes of materials introduced into the reactor coil, the reaction scale was specified to 1 millimole scale. Pumps A (aniline: 0.277 mL / min) and B (DNNSA: 0.1 mL / min) were started to initiate the formation of an aniline-DNNSA emulsion. Once a milky emulsion was produced in the second T-mixer, pump C (oxidant: 0.05 mL / min) was started to initiate the reaction. After a period of time, the flow rate was observed to rapidly decrease due to an increase in back pressure in the system. In this example, the first 10 mL exiting the reactor coil was observed to contain a heterogeneous mixture of PANI polymer in the organic phase and some aqueous phase by-products. This initial fraction was extracted with xylene and the extract was washed twice with water. The dried organic layer of this solvent extract was concentrated in vacuum to yield 0.10 g of a blue-green film (UV-Vis spectrum 500 in Figure 11). UV-Vis (dried film) 285, 325, 373, 851 nm. Elemental analysis: C 72.64, H 10.01, N 1.84, S 5.41. After about 30 minutes total, flow from Pump A was stopped. In one example, the reagent syringe was replaced with a syringe containing water to stop polymerization in the flow reactor.

[0044] In this example, after the polymerization was stopped, the flow reactor was washed with a volume of water to remove any water-soluble reactants or by-products. No PANI product was collected from this water wash, and a significant blue color remained in the flow reactor tube. Following this water wash, the reactor was then washed with a volume of xylene, and the collected washes gave a concentrated blue extract. The solvent extract was dried and concentrated in vacuum to yield 0.31 g of a blue-green film. UV-Vis (dried film) 285, 325, 371, 839 nm is shown in Figure 11 as spectrum 550. Elemental analysis: C 73.49, H 10.42, N 1.87, S 5.14.

[0045] Synthesis of Polyaniline-Dinonylnaphthalene Sulfonic Acid (7.5 mmol scale). The flow reactor system was set up as described for the 1 mmol scale reaction above, but the pump position and syringe dimensions were altered to overcome the initial backpressure from the formation and deposition of polymeric material in the flow reactor. Using smaller syringes, the pumps were equipped as follows: Pump A: 20 mL syringe of 0.375 M aniline, KD Scientific pump. Pump B: 10 mL syringe of 1 M DNNSA solution, KD Scientific pump. Pump C: 2 M (NH 4 ) 2 S 2 O 8 10 mL syringe, Sage pump. Samples were collected in 3.5 mL fractions. The initial heterogeneous fraction was processed as previously described to yield 0.206 g of a blue-green residue. UV-Vis (dried film) 285, 325, 802. Elemental analysis: C 72.70, H 9.83, N 2.02, S 5.01.

[0046] After collecting the initial fractions, the flow reactor tube was washed with water using the HPLC pump. The initial measured backpressure for the water wash was 200 psi. The reactor was then washed with 15 mL of xylene. Once the xylene had replaced the water in the reactor coil, the backpressure dropped to less than 5 psi. The xylene wash yielded the major fraction of product, 3.58 g of blue residue. UV-Vis (dry film) 284, 325, 768 nm. Elemental analysis: C 74.39, H 9.99, N 1.98, S 4.77. The yield from a 7.5 mmol scale reaction based on a 1:1 stoichiometry of PANI:DNNSA was 3.79 g (91.6%).

[0047] Current flow reactors, including microreactors, use microfluidic chips or miniaturized columns and specialized equipment for flow device control. The present system and method provide an apparatus that can be assembled from syringe pumps, commercially available HPLC tubing, and an aluminum holder equipped with a standard thermocouple temperature control device. By using syringe pumps to control the flow of reagents, the pressure inside the reactor can be maintained well below the limits of the flow reactor tubing and low pressure fittings. Reagent concentrations and flow rates can be selected to result in an overall reaction concentration similar to that used in batch processing. For example, for PANI-DNNSA, the reaction concentration after mixing can be 0.23 M. This value is very close to the value calculated for the batch reaction described above.

[0048] The stoichiometric amounts of the reagents used in this disclosure were approximately equal for each of aniline, DNNSA, and ammonium persulfate, although other stoichiometric amounts may be used. For PANI, the monomer concentration was limited by its solubility in water, which was slightly higher than 0.375M at room temperature. Thus, in an exemplary experiment using PANI, pump A was filled with a 0.375M aniline solution and fed at 0.277mL / min. A DNNSA solution, about 50% w / w n-butyl glycol or 1.04M solution, was placed in pump B and fed at 0.1mL / min. Pump C was filled with a freshly prepared 2M ammonium persulfate solution fed at 0.05mL / min. Each reagent had a feed rate of 0.1 mmol / min, resulting in a total flow rate of the reaction mixture of 0.427mL / min. Other total flow rates may be used depending on the system parameters and polymerization products.

[0049] It should be noted that both the 1 mmol scale and the 7.5 mmol scale resulted in two distinct fractions, the initial fraction obtained in the biphasic reaction mixture purified by the normal extraction path and the larger scale reaction. The first fraction was a minor component representing 5% of the total material. Unexpectedly, the major fraction stuck to the flow reactor tubes. It did not completely quench the flow in the reactor, but it did increase the back pressure of the system. Therefore, back pressure monitoring was used to facilitate monitoring of the reaction process. Based on these results, it is possible to produce PANI-DNNSA at a gram / day rate, for example, 10 grams / day, or 20 grams / day, up to 50 grams / day, in a given flow reactor unit. The production amount can be multiplied by the number of parallel flow reactors used. Thus, the present disclosure provides a method to produce large amounts of compositionally consistent conductive polymer salts such as PANI-DNNSA in a cost-effective manner with relatively high yields and high production rates.

[0050] In both experiments, the reactor coil was washed with water to remove aqueous impurities such as sulfuric acid and excess oxidation catalyst, but the major product was obtained by washing the flow reactor with xylene. Due to the solubility of the PANI-DNNSA product, it is possible to obtain the product with a minimal amount of xylene. Deposition of the PANI-DNNSA product is an advantageous result, allowing, for example, removal of aqueous impurities and direct extraction of the polymer in xylene without downstream processing of the reactor, providing a product that can be spin-coated or precipitated.

[0051] FIG. 11 shows the UV-Vis spectrum of PANI:DNNSA as a dry film. The UV-Vis spectrum 500 of the early first fraction shows similarity to the UV-Vis spectrum 550 of the major late fraction as product. The expected UV absorption is seen for the incorporation of aniline rings and naphthalene rings in the DNNSA salt. Elemental analysis was obtained and mole percent analysis of N and S shows that these elements are present in equal molar amounts, suggesting a 1:1 ratio of the nitrogen component of PANI to the sulfonic acid of DNNSA or a 1:1 PANI:DNNSA polymeric material. Previously reported conductive PANI:DNNSA polymers were obtained in a 2:1 ratio. The current 1:1 material is believed to be a result of a slight molar excess of DNNSA used in the process. Manipulation of the PANI:DNNSA ratio is possible in the present system and method, allowing for variation of the ratio in the finished polymerized product.

[0052] Initial experiments with this flow reactor apparatus have demonstrated the feasibility of preparing conductive polymer salts from monomers and acids. The disclosed system and method provide for forming an emulsion and introducing a catalyst into the flow reactor along with the emulsion. For illustrative purposes only, PANI-DNNSA soluble polymers were prepared by the current flow reactor process. For the PANI system, other organic acids for salt formation may be used. Other monomer / salt systems, such as thiophene / polystyrene sulfonate, may be used for in situ doping during monomer polymerization of conductive polymers.

[0053] Additionally, the present disclosure includes embodiments according to the following clauses:

[0054] Clause 1 1. A method comprising: introducing an emulsion of a monomer and an acid into a flow reactor, the flow reactor comprising a length of tubing having an inner diameter of between about 1 and about 1000 micrometers; polymerizing the monomer; and forming a salt of the polymerized monomer with an acid within the length of tubing.

[0055] Clause 2 13. The method of claim 1, further comprising introducing a catalyst into the emulsion.

[0056] Clause 3 3. The method of claim 1 or 2, further comprising introducing a catalyst into the flow reactor.

[0057] Clause 4 2. The method of claim 1, wherein the emulsion comprises an aqueous solution of the monomer and an organic solvent solution of the acid.

[0058] Clause 5 5. The method of any one of clauses 1 to 4, further comprising maintaining the salt of the polymerized monomer in a length of tube.

[0059] Clause 6 6. The method of claim 5, further comprising recovering a salt of the polymerized monomer from the tube.

[0060] Clause 7 7. The method of clause 6, wherein recovering the polymerized monomer salt from the tube uses an organic solvent.

[0061] Clause 8 8. The method of any one of clauses 1 to 7, further comprising maintaining the polymerized acid salt in a length of tubing and removing unreacted monomer or acid from the tube with water.

[0062] Clause 9 2. The method of claim 1, wherein a length of tube is wound.

[0063] Clause 10 2. The method of claim 1, wherein the tube is a fluoropolymer.

[0064] Clause 11 2. The method of claim 1, wherein the flow reactor comprises a plurality of tubes arranged in a parallel flow configuration.

[0065] Clause 12 12. The method of any one of clauses 1 to 11, wherein the polymerizing is carried out under diffusion-limiting conditions.

[0066] Clause 13 The method of claim 1, wherein the monomer is an aniline or a thiophene.

[0067] Clause 14 2. The method of claim 1, wherein the acid is an organic acid selected from polystyrene sulfonic acid or dinonylnaphthalene sulfonic acid.

[0068] Clause 15 1. 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 tubing having an inner diameter of between about 1 and about 1000 micrometers; introducing an oxidizing agent into the emulsion or the flow reactor; and polymerizing the aniline within the inner diameter of the length of tubing to form its acid salt.

[0069] Clause 16 16. The method of claim 15, wherein the length of tube is wound.

[0070] Clause 17 16. The method of claim 15, wherein the polymerized salt of aniline is substantially contained within a length of tube, the tube being a fluoropolymer.

[0071] Clause 18 18. The method of claim 17, further comprising recovering the salt of the polymerized aniline from the tube using an organic solvent.

[0072] Clause 19 16. The method of claim 15, wherein the molar ratio of aniline to organic sulfonic acid is between 1 and 0.2.

[0073] Clause 20 16. The method of claim 15, wherein the total flow rate of aniline is from about 0.01 mmol / min to about 0.2 mmol / min, resulting in a flow rate of the emulsion reaction mixture into the flow reactor of from 0.1 ml / min to about 0.5 ml / min.

[0074] Clause 21 16. The method of claim 15, wherein the oxidizing agent is introduced at a flow rate of about 0.001 to about 0.2 milliliters per minute.

[0075] Clause 22 1. A polymerization apparatus for reacting one or more monomers to produce one or more polymers, the polymerization apparatus comprising: a quantity of tubing having an inner diameter of between about 1 and about 1000 micrometers, the tube including at least one inlet port and at least one outlet port, the quantity of tubing having at least one inlet port for receiving a reactant composition, and at least one outlet port; a temperature controller sized to receive at least a portion of the tubing; a mixing chamber having an inlet port, and an outlet port fluidly connected to the inlet port of the tubing; and at least one fluid flow control device fluidly connected to the inlet port of the mixing chamber.

[0076] Clause 23 23. The polymerization apparatus of clause 22, wherein the tube is wrapped around the temperature controller.

[0077] Clause 24 23. The polymerization apparatus of clause 22, wherein the at least one fluid control device comprises a monomer fluid flow control device and an acid fluid flow control device.

[0078] Clause 25 25. The polymerization apparatus of any one of clauses 22 to 24, further comprising a second mixing chamber fluidly connected to the outlet of the mixing chamber and the inlet of the tube.

[0079] Clause 26 26. The polymerization apparatus of any one of clauses 22 to 25, further comprising a catalyst fluid flow control device fluidly connected to the second mixing chamber or tube.

[0080] Clause 27 1. A method comprising forming an emulsion of a monomer and an acid, introducing the emulsion into a flow reactor, the flow reactor comprising a length of tubing having an inner diameter of between about 1 and about 1000 micrometers, and polymerizing the monomer to form its acid salt.

[0081] Clause 28 28. The method of clause 27, further comprising recovering a salt of the polymerized monomer.

[0082] Clause 29 28. The method of claim 27, further comprising introducing a catalyst into the emulsion or flow reactor.

[0083] Clause 30 28. The method of claim 27, wherein the emulsion comprises an aqueous solution of the monomer and an organic solvent solution of the acid.

[0084] Clause 31 28. The method of claim 27, wherein the length of tube is wound.

[0085] Clause 32 28. The method of claim 27, wherein the polymerized monomer salt is substantially contained within a length of tube, the tube being a fluoropolymer.

[0086] Clause 33 33. The method of any one of clauses 27 to 32, further comprising removing unreacted material from the tube with water.

[0087] Clause 34 33. The method of claim 32, further comprising recovering the salt of the polymerized monomer from the tube using an organic solvent.

[0088] Clause 35 1. 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 tubing having an inner diameter of between about 1 and about 1000 micrometers; introducing an oxidizing agent into the emulsion or the flow reactor; and polymerizing the aniline within the inner diameter of the length of tubing to form its acid salt.

[0089] The description of the preferred embodiments of the present disclosure have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. The examples have been chosen and described to provide the best illustration of the principles of the present disclosure and its practical application, thereby enabling those skilled in the art to utilize the various examples, and various modifications thereof, as suited to the particular uses anticipated.

Claims

1. 1. A system for polymerizing one or more monomers to produce a polymer salt, comprising: A length of tubing having an inner diameter that provides diffusion limited polymerization conditions, at least one inlet port configured to receive an emulsified reactant composition comprising an aqueous monomer solution and a non-aqueous solution; and at least one outlet port configured for discharging the polymer salt; a length of tube having a temperature controller sized to receive at least a portion of the length of tubing; a mixing chamber configured to emulsify a reactant composition, the mixing chamber having an inlet and an outlet, the outlet being fluidly connected to the inlet port of the tube; at least one fluid flow control device fluidly connected to the inlet of the mixing chamber; Including, A system wherein said polymeric salt has a molar ratio of monomer to salt of from 1:1 to 1:0.2, said monomer being aniline, and said nonaqueous solution being dinonylnaphthalenesulfonic acid.

2. 1. A system for diffusion limited synthesis of conductive polymer salts, comprising: A length of tubing having an inner diameter that provides diffusion limited polymerization conditions, at least one inlet port configured to receive an emulsified reactant composition comprising an aqueous monomer solution and a non-aqueous acid solution; and at least one exit port configured for discharging the diffusion-limited polymerized conductive polymer salt; a length of tube having a temperature controller sized to receive at least a portion of the length of tubing; a mixing chamber configured to emulsify a reactant composition, the mixing chamber having an inlet and an outlet, the outlet being fluidly connected to the inlet port of the length of tubing; at least one fluid flow control device fluidly connected to the inlet of the mixing chamber; Including, A system wherein the conductive polymer salt has a molar ratio of monomer to salt of 1:1 to 1:0.2, the monomer being aniline, and the non-aqueous acid solution being dinonylnaphthalenesulfonic acid.

3. introducing an emulsion of an aqueous solution of a monomer and an organic solvent solution of an acid into a flow reactor, the flow reactor comprising a length of tubing having an inner diameter; polymerizing the monomers under diffusion-limited conditions in the length of tube; forming a salt of the polymerized monomer within the length of tube with the acid; 1. A method for producing a salt of a polymerized monomer comprising: A process wherein said polymerized monomer salt has a molar ratio of monomer to salt of from 1:1 to 1:0.2, said monomer being aniline, and said organic solvent solution of acid being dinonylnaphthalenesulfonic acid.

4. introducing an emulsion of an aqueous solution of aniline and an organic solvent solution of an organic acid into a flow reactor, the flow reactor comprising a length of tubing having an inner diameter; introducing an oxidant into the emulsion or the flow reactor; polymerizing the aniline under diffusion-limited conditions within the inner diameter of the length of tubing and forming its acid salt; 1. A method for producing an acid salt of polymerized aniline comprising: The process wherein the polymerized aniline acid salt has a molar ratio of polymerized aniline to acid salt of from 1:1 to 1:0.2, the monomer being aniline, and the organic acid in organic solvent solution is dinonylnaphthalenesulfonic acid.

5. introducing an emulsion of an aqueous solution of a monomer and an organic solvent solution of an acid into a flow reactor, said flow reactor comprising a length of tubing, said length of tubing comprising: Inner diameter, and A surface for receiving polymerized monomer and introducing introducing a catalyst into the emulsion; polymerizing the monomer under diffusion-limited conditions within the bore; depositing at least a portion of the polymerized monomer on the surface within the length of tube; forming a salt of the polymerized monomer with the acid; 1. A method for producing a salt of a polymerized monomer comprising: A process wherein said polymerized monomer salt has a molar ratio of monomer to salt of from 1:1 to 1:0.2, said monomer being aniline, and said organic solvent solution of acid being dinonylnaphthalenesulfonic acid.

6. introducing an emulsion of monomer and acid into a flow reactor, the flow reactor comprising a length of tubing; polymerizing the monomer; forming a salt of the polymerized monomer with the acid in the length of tube, wherein a majority of the salt of the polymerized monomer deposits on a wall of the tube; removing water soluble reactants, reagents and / or by-products from the polymerized monomer salt by washing with water; eluting said polymerized monomer salt from said wall of said tube with an organic solvent; 1. A method for producing a polymer comprising: A process wherein said monomer is aniline, said acid is dinonylnaphthalenesulfonic acid, and said polymerized monomer salt has a molar ratio of monomer to salt of from 1:1 to 1:0.2.

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