Oxygen-Based Control of Polymerization Reactions

Abstract

A method and apparatus for controlling a polymerization reaction using controlled addition of oxygen to a reactor. The method may include providing a reactor containing one or more chemical components suitable for promoting the polymerization reaction and continuously measuring one or more polymer properties of a polymer produced by the polymerization reaction in the reactor. The method may also include using a control algorithm to determine, based on the continuous measurements of the one or more polymer properties, an amount of oxygen to add to the reactor at one or more times during the polymerization reaction to cause the one or more polymer properties to follow a predetermined target trajectory.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS (CROSS REFERENCE TO RELATED APPLICATIONS) This patent application claims the benefit under 35 U.S.C. §119(e) of U.S. patent application Ser. No. 63 / 268,602, entitled “Oxygen-Based Control of Polymerization Reactions,” filed on February 26, 2022, which is incorporated by reference in its entirety. Field

[0002] The present disclosure relates generally to methods for controlling polymerization reactions. In particular, the present disclosure relates to controlling polymerization reactions using controlled addition of oxygen. In some non-limiting examples, the methods of the present disclosure can include methods for controlling the molecular weight and related properties of polymer and / or copolymer compositions produced during a polymerization reaction by controlled addition of oxygen. [Background technology]

[0003] background Many properties of polymeric materials, such as tensile strength and processability, are due to the molecular weight of the constituent polymer molecules. Controlling polymer molecular weight is therefore the ability to determine polymer product properties. Similarly, copolymerization allows two or more comonomers of different properties to be combined together to produce new material properties. One example is the copolymerization of polybutadiene with styrene to produce non-brittle, high impact polystyrene. Pairs or groups of comonomers can be copolymerized to impart many desirable characteristics to polymer products. When two incompatible monomer types are copolymerized, self-assembled structures can form both in the bulk material and on the surface.

[0004] There are several ways in which the molecular weight of a polymer can be controlled during polymerization. These include the use of different temperatures, initiators, catalysts, and transfer agents. In semi-batch operations, the monomer feed to the reactor can be used to control the molecular weight and copolymer composition. However, additional methods for controlling the polymerization reaction are desirable. Summary of the Invention

[0005] Quick Overview In one embodiment, an apparatus for controlling a polymerization reaction by varying oxygen may include a reactor within which the polymerization reaction occurs. The apparatus may also include a means for controlled delivery of oxygen to the reactor. The apparatus may also include a means for continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor.

[0006] In another aspect, a method for controlling a polymerization reaction by varying oxygen is provided. The method may include providing a reactor containing one or more chemical components suitable for promoting the polymerization reaction. The method may also include continuously measuring one or more polymer properties of a polymer produced by the polymerization reaction in the reactor. The method may also include using a control algorithm to determine an amount of oxygen to add to the reactor at one or more times during the polymerization reaction based on the one or more continuously measured polymer properties to cause the one or more polymer properties to follow a predetermined target trajectory.

[0007] Additional embodiments and features are set forth in part in the description which follows, and will become apparent to those skilled in the art upon examination of the specification or may be learned by practice of the disclosed subject matter. A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings which form a part of this disclosure. [Brief description of the drawings]

[0008] To explain how the advantages and features of the present disclosure can be obtained, reference will be made to embodiments thereof illustrated in the accompanying drawings. With the understanding that these drawings represent exemplary embodiments of the present disclosure and therefore should not be considered as limiting its scope, the principles of the present specification will be explained with added specificity and detail by using the accompanying drawings.

[0009] [Figure 1A] FIG. 1A shows a system diagram for controlling a polymerization reaction using controlled addition of oxygen, according to an exemplary embodiment of the present disclosure.

[0010] [Figure 1B] FIG. 1B shows a process flow diagram for controlling a polymerization reaction using controlled addition of oxygen, according to an exemplary embodiment of the present disclosure.

[0011] [Diagram 2] FIG. 2 shows raw light scattering and UV absorption data versus time in a reactor for two acrylamide (Am) free radical reactions according to an exemplary embodiment of the present disclosure.

[0012] [Diagram 3] FIG. 3 illustrates data showing the concentration of dissolved O2 (DO) versus time in a reactor as measured by a DO probe in the reactor in accordance with an exemplary embodiment of the present invention.

[0013] [Figure 4] FIG. 4 presents data showing a comparison in short and long conversion plateaus between the two air flow rates of 192 standard cubic centimeters per minute (sccm) and 15 sccm shown in FIGS. 2 and 3 in accordance with an exemplary embodiment of the present disclosure.

[0014] [Diagram 5]FIG. 5 shows data showing the concentration of polyacrylamide (pAm) versus reaction time, derived from the concentration of Am or [Am] via mass balance, for a reaction without O2 and a second reaction with 6 sccm, in accordance with an exemplary embodiment of the present disclosure.

[0015] [Figure 6] FIG. 6 shows data comparing the cumulative weight average molecular weight Mw for the two reactions of FIG. 5, according to an exemplary embodiment of the present disclosure.

[0016] [Figure 7] FIG. 7 shows data illustrating instantaneous weight average molecular weight Mw,inst versus concentration in pAm for the data shown in FIG. 6 calculated according to Equation 4, in accordance with an exemplary embodiment of the present disclosure.

[0017] [Figure 8] FIG. 8 illustrates data showing cumulative reduced viscosity (RV) obtained from highly dilute sample streams versus concentration in pAm or [pAm], according to an exemplary embodiment of the present disclosure.

[0018] [Figure 9] FIG. 9 illustrates data showing concentration of RVinst versus pAm, calculated by Equation 4, substituting RV for Mw, in accordance with an exemplary embodiment of the present disclosure.

[0019] [Figure 10] FIG. 10 shows a calibration curve illustrating how Mw,inst varies with flow rate Q as a function of Am concentration in the reactor according to an exemplary embodiment of the present disclosure.

[0020] [Figure 11]FIG. 11 illustrates the Mw versus concentration of polystyrene sulfonate (pSS) or [pSS] and the use of O2 to shorten pSS chains via chain termination, and how low the O2 flow must be below the O2 threshold, [O2]t, to successfully shorten chain termination of styrene sulfonate (SS) free radical polymerization in water at 100 mM NaCl ionic strength, according to an exemplary embodiment of the present disclosure.

[0021] [Figure 12] FIG. 12 is a flow chart illustrating steps for controlling a polymerization reaction using the addition of oxygen according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Detailed Description The present disclosure provides a method for controlling polymerization reactions that involves using low, controlled levels of oxygen (O2) as a reversible means of actively controlling molecular weight. The composition of the copolymer can also be controlled with O2.

[0023] The molecular weight depends on several factors including temperature, initiator type and concentration, monomer concentration, and the type of polymerization mechanism, e.g., free radical, controlled free radical, or step-propagation reactions such as polycondensation. Chain transfer agents (CTAs), such as sodium formate for polyacrylamide molecular weight control, can be used to control the instantaneous weight-average kinetic chain length, X w,inst (weight average number of monomers in a polymer chain) shortens the kinetic chain length according to the basic free radical equation for TIFF2025507697000002.tif35150 (Formula 1)

[0024] where light scattering is the cumulative weight average molecular weight M w The instantaneous weight average molecular weight M w,inst Since the weighted average is calculated, k p , k t, and k3 are the propagation, termination and chain transfer rate constants, respectively, and [M], [R] and [CTA] are the molar concentrations of monomer, free radical and chain transfer agent, respectively. Y is a dimensionless constant that varies from 1 for recombination to 2 for pure disproportionation, and has a value between 1 and 2 when both processes occur. The dimensionless constant d is the instantaneous polydispersity index M, which is usually around 2 in free radical polymerizations. w As [CTA] increases, the chain length X w,inst decreases. When CTA is added to the chemical, [CTA] remains approximately constant in the denominator and the chain shortening effect is irreversible. M w,inst is calculated by simply multiplying it by the monomer molecular weight m (g / mol) w,inst Related to;M w,inst =mX w,inst For acrylamide, m = 71.08 g / mol.

[0025] If [CTA] can be controlled in Equation 1, then increasing [CTA] will give X w,inst can be increased by lowering [CTA] and decreasing [CTA]. This disclosure envisions molecular oxygen O2 as a very flexible CTA that can freely modulate the value in the denominator [CTA]. Although it is commonly known that O2 inhibits reactions, its practical use has generally been limited to adding bursts of air or O2 to slow or stop runaway exothermic reactions. A low O2 concentration threshold for stopping reactions, [O2]t, means that small amounts of O2 are used to stop free radical reactions.

[0026] One of the reasons why O2 has not been used as a CTA so far is believed to be that the concentration of O2 that completely stops the free radical reaction is low, on the order of 0.1 mg / L, while the saturation of dissolved O2 at T=25°C is about 6.56 mg / L. This means that this narrow O2 concentration "window" below [O2]t can be used for molecular weight control and can be used as a means of fine control of low gas flow rates. Furthermore, continuous monitoring of molecular weight, monomer concentration, conversion, reduced viscosity, composition (for copolymers), and other properties can be used to observe both the chain termination effect, as well as control of the molecular weight and related properties of the polymer, and / or the composition of the copolymer produced during the polymerization reaction by the controlled addition of oxygen.

[0027] 1A shows a system diagram for controlling a polymerization reaction using controlled addition of oxygen, according to an exemplary embodiment of the present disclosure. The system 100 includes a reactor 102 in which a polymerization reaction takes place to produce a polymer. The reactor 102 can optionally include a submerged oxygen sensor or probe 114 for continuously monitoring the concentration of oxygen. Optionally, a probe 114 for dissolved O2 can be placed in the reactor 102, similar to the one used for some of the data presented herein.

[0028] In some variations, oxygen may be delivered to the reactor in gaseous form.

[0029] The system 100 also includes a controller 104 for controlling control variables 103, such as inert gases, oxygen concentration, temperature, monomers, initiators, catalysts, branching or crosslinking agents, chain transfer agents, and / or chain terminators, among others. The controller 104 includes means for varying one or more additional control variables for the reactor.

[0030] In some variations, the one or more additional control variables are selected from the group consisting of temperature, addition of monomer to the reaction, comonomers, initiators, catalysts, branching / crosslinking agents, and chain transfer agents.

[0031] The controller 104 provides a means for controlled delivery of oxygen to the reactor 102. The controller 104 includes a means for fine low-flow control of O2 inflow to the reactor 102 and a means for purging O2 from the reactor 102 with a flow of inert gas (e.g., nitrogen or argon). The controller 104 is operable to automatically deliver an amount of oxygen to the reactor determined by a control algorithm 106.

[0032] The system 100 also includes a control algorithm 106 for controlling the control variables 103 via the controller 104. The control algorithm 106 is stored on a storage device or a tangible, non-transitory computer readable medium. The instructions, when executed by the processor 108, are operable to use the control algorithm 106 to determine an amount of oxygen to add to the reactor at one or more points during the polymerization reaction based on continuous measurements of one or more polymer properties to cause the one or more polymer properties to follow a predetermined target trajectory.

[0033] System 100 also includes an Automatic Continuous Online Monitoring of Polymerization Reactions (ACOMP) system 112, which produces measured polymer properties. The ACOMP system 112 is an efficient means for such monitoring and enables one embodiment of the present disclosure.

[0034] The ACOMP system 112 includes a monitor 110 that can monitor, among other things, monomer and polymer concentrations. For example, the monitor 110 provides a means for continuously monitoring the monomer and polymer concentrations in the reactor. The monitor 110 provides a means for continuously monitoring viscosity, such as a capillary viscometer. The monitor 110 also monitors, among other things, the cumulative weight average molecular weight M w For example, the monitor 110 may provide a means for continuously monitoring the cumulative weight average molecular weight M w The instantaneous weight average molecular weight M w,inst is calculated by the ACOMP system 112 based on Equation 1.

[0035] The ACOMP system 112 also includes a processor 108 that can receive and process data collected from the monitor 110. For example, the processor 108 can be configured to receive information from a means for continuously monitoring the concentrations of monomer and polymer in the reactor.

[0036] The ACOMP system 112 also includes a calculation module 111 that calculates one or more polymer properties based on the data received by the processor 108 and generates the control algorithm 106 using the processor 108 based on comparing the measured polymer properties to predetermined targets for the one or more polymer properties.

[0037] The control algorithm 106 can dictate which controlled variables 103 can be manually controlled by an operator, allowing for “computation-aided active control.” The controlled variables 103 can be automatically controlled via the controller 104, which is a computation-based controller and allows for automatic active control.

[0038] The ACOMP system 112 may include a tangible, non-transitory computer readable medium having encoded thereon instructions that, when executed by the processor 108, are operable to use the control algorithm 106 to determine, based on continuous measurements of one or more polymer properties, an amount of oxygen to add to the reactor to stop or slow down the polymerization reaction.

[0039] As used herein, the term "polymer reaction" refers to any type of chemical or physical reaction involving polymers in all its forms, including, but not limited to, any type of reaction that covalently produces polymers from monomers or comonomers, causes branching or crosslinking reactions, causes cleavage of polymer bonds to produce smaller polymers, causes the formation of block copolymers, causes the formation of star-shaped, comb-shaped, dendritic, or other highly specific polymer architectures, causes chemical modification of polymers, such as impregnation of polymers with negative and / or positive charges, impregnation of polymers with acid or base properties, linking of polymers, or growth of polymers from nano- or microparticles, such as silica, metals such as silver or gold, gels, metal oxides such as titanium dioxide, clay, and causes the formation of reversible or irreversible supramolecular assemblies of polymers and other particles.

[0040] Regarding the reaction to produce a polymer from a monomer, any type of polymerization mechanism can be used. Thus, it includes chain growth and step growth reactions. The former are free radical and controlled radical polymerization. Under controlled radical polymerization, methods such as, but not limited to, ring-opening metathesis polymerization (ROMP), atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP) are found. Polymer reactions can occur in solution phase, bulk phase, and heterogeneous phase, such as micelles, emulsions, inverse emulsions, and dispersions. It includes metallocene-based chain growth, such as those used in polyolefins. Step growth includes polycondensation reactions, such as those used in the manufacture of polypeptides, polynucleotides, polyimides, polyamides, and polyurethanes. As used herein, the term "inert gas" refers to gases such as nitrogen (N2) and other non-reactive gases in all its forms, including, but not limited to, the Group 8A inert gases of the periodic table: argon, helium, krypton, neon, xenon, and radon.

[0041] This disclosure does not impose limitations on the type of polymer reactor, also called polymer reaction vessel, to which it is applied. Polymer reactors can be as small as sub-milliliters, and as large as tens or hundreds of thousands of liters. Polymer reactors can be made from many different materials, including, but not limited to, metals such as stainless steel or aluminum, glass, porcelain, and ceramics. Polymer reactors can be batch-type, the kind that can feed reagents, sometimes called "semi-batch," or continuous. When a continuous reactor is used, the approach differs depending on the type of continuous reactor. For example, in a long tubular continuous reactor, different actively controlled process stages can occur at different points along the trajectory of the reacting fluids through the reactor. In a continuous stirred tank reactor, a steady state is reached in the reactor, and multiple continuously stirred tank reactors (CSTRs) can be arranged in series flow to reach different stages of actively controlled multi-stage processing.

[0042] To achieve the conditions for active control of polymer molecular weight (MW), it is useful to monitor the molecular weight, to be controlled, and related quantities such as monomer and polymer composition, and to monitor these properties frequently enough to allow active control of polymer molecular weight. If the composition is controlled, it is useful to be able to distinguish and monitor the progress of the conversion of the comonomers involved. Measurements can be made, possibly frequently enough, by monitors 110 including in-reactor spectroscopic probes such as Raman scattering and infrared (IR). In the ACOMP system 112, the discrimination of the comonomers has been achieved with refractive index, ultraviolet absorption, near infrared, infrared, and electrical conductivity. When chiral molecules are mixed with achiral molecules, the former can be discriminated using a circular polarimeter or other sensors of optical activity such as circular dichroism or circular birefringence. Monitors 110 including nuclear magnetic resonance (NMR) can also be used in the ACOMP system 112 to discriminate the comonomers. The ACOMP system is also called the ACOMP platform.

[0043] Measurement of molecular weight using the ACOMP system 112 includes polygonal total intensity light scattering, if used, along with polymer concentration determination. Intrinsic viscosity (IV) is also related to molecular weight, and a capillary type viscometer is frequently used with the ACOMP detector array. Intrinsic viscosity in combination with molecular weight can be used to assess branching. Simultaneous measurement of low and high shear viscosity in the ACOMP system 112 can also be used to assess branching via shear non-Newtonian shear behavior.

[0044] To perform active control of molecular weight, information about reaction characteristics can be used at a frequency sufficient to allow control actions to be taken at time intervals short compared to the time of the reaction. As used herein, the term "sufficient frequency" in all its forms refers to a frequency of data acquisition such that control of the desired reaction characteristic is performed in a time much shorter than the time at which substantial deviation of the controlled characteristic can occur. "Substantial deviation" depends on the degree to which control is desired. For example, and not by way of limitation, in some cases it may be acceptable to control the desired characteristic to within 35% of the model trajectory, while in other cases control to within 10%, within 5%, or even less than 1% deviation may be used. A sufficient frequency of reaction characteristic information is a frequency sufficient to control the characteristic within the desired bounds of deviation from the model trajectory.

[0045] According to a non-limiting embodiment of the present invention, the ACOMP system 112 wMultiple reaction properties such as reduced viscosity, conversion, monomer and polymer concentrations, and comonomer composition are measured once per second. Faster and slower rates can give a general sense of frequency in reactions that typically last tens of minutes or hours. When the period of data measurement (the inverse of frequency) is well within the time scale to control deviations, such measurements are often called "continuous", as in the term Automatic Continuous Online Monitoring of Polymerization Reactions (ACOMP). Manual sampling methods, such as those widely used in both polymer manufacturing and laboratories, rarely have a high enough frequency for active control. Similarly, online chromatographic methods generally do not have a sufficient frequency but can be used in this application.

[0046] Active control of one or more reaction variables during a reaction phase can be accomplished by one of three means according to the present disclosure. In "manual active control", a human has access to data of relevant characteristics of sufficient frequency upon which the human follows a reaction trajectory for one or more relevant characteristics by manually controlling one or more process control variables as described in the "Control Means" section. A control algorithm 106 dictates which control variables may be manually controlled by an operator, allowing for "computation-assisted active control". Finally, the process control variables are automatically controlled via the computation-based controller 104, allowing for automatic active control.

[0047] As used herein, the term "reaction trajectory" refers to a specific mathematical form of a reaction characteristic versus a dependent variable, such as molecular weight (MW) or composition, in all of its forms. Common dependent variables in polymerization reactions are time and polymer or monomer concentration. The reaction trajectory can determine the final properties of a polymer, including its molecular weight and composition distribution. In the case of a copolymer, the instantaneous composition trajectory can determine its final composition distribution. Thus, the properties of the final polymer are controlled by controlling the reaction trajectory.

[0048] Here, cumulative weight average molecular weight (M), which can be measured frequently or continuously during polymer synthesis, such as by using the ACOMP system 112, is used. w ) and other specific reaction properties are contemplated. Consider a general property X. Online monitoring of the reactor contents provides the cumulative value X of X in the reactor. c The accumulation of X and the resulting distribution gives the instantaneous value of X, i.e., X inst , and how many X in the cumulative population inst It depends on what is added. Specifically, X c and X inst The relationship between is naturally given by Equation 2 as follows: TIFF2025507697000003.tif50162 (Formula 2)

[0049] Here, C p is the polymer concentration. X inst (C p ) is the measured cumulative value X from Equation 1. c (C p ) and C p Thus, via equation 3, it can be calculated as follows: TIFF2025507697000004.tif35142 (Formula 3)

[0050] M w (C p ) can be measured directly from the light scattering and concentration detectors in the ACOMP system. w,inst (C p ) is expressed as M according to Eq. 4 and Eq. 2. w (C p ) can be calculated from the ACOMP value of TIFF2025507697000005.tif45165 (Formula 4)

[0051] M w and C. p From the primary ACOMP value of M w,instCalculating the instantaneous mass average of the molecular weight distribution (MWD) allows for a histogram display of the MWD as the synthesis proceeds. Up to this point, all quantities are model independent and based on primary detector measurements.

[0052] Similarly, N different copolymers, F inst,j The instantaneous composition of comonomer j in a copolymer having TIFF2025507697000006.tif23138 (Formula 5)

[0053] F inst,j can be calculated from the concentrations of the individual comonomers, dC p ,j=-dC m,j i.e., minus the monomer dC m,j The loss of C in polymer form m,j This appears as an increase in

[0054] The apparatus, methods, and systems of the present disclosure include a reactor 102 in which a polymerization reaction occurs, a means for continuous analysis, a means for control of desired control variables, and a means for delivering these control variables to the reactor. The means for controlled delivery of oxygen to the reactor can include a controller 104 operable to automatically deliver an amount of oxygen to the reactor 102 determined by a control algorithm 106.

[0055] FIG. 1B illustrates a non-limiting process flow diagram for controlling a polymerization reaction using controlled addition of oxygen, according to an exemplary embodiment of the present disclosure. As shown in FIG. 1B, process 101 also includes continuous analysis 103, which includes monitoring monomer and polymer concentrations by using a monitor 110 in step 105. Monitor 110 may also monitor other reaction properties, such as viscosity, among others. Continuous analysis 103 also includes monitoring polymer properties (e.g., M) by using an ACOMP system 112 in step 107. w,inst , F inst,j )

[0056] The process 101 also includes feedback control 109, which involves comparing the calculated polymer property with a desired target for the polymer property by using the processor 108 in step 111 and generating a control algorithm in step 113.

[0057] The process 101 also includes varying control variables 103 for the reactor 102 in step 115. The control variables 103 include, among others, one or more of temperature and the addition of monomers, comonomers, initiators, catalysts, branching / crosslinking agents, chain transfer agents, and / or chain terminators and shorteners to the reaction. The process 101 also includes a polymer reaction in the reactor 102 to produce a desired polymer.

[0058] For the results shown below, the reactor 102 contained about 500 cubic centimeters (ccs) of aqueous reaction medium and about 100 ccs of headspace. Continuous reaction monitoring data was acquired using a Fluence Analytics third generation ACOMP instrument, the ACOMP system 112. An Aalborg gas flow controller (GFC) with a flow rate of 0-10 sccm was used to introduce O2 into the reactor 102 from a compressed air tank ultra zero grade (about 20% O2). An MKS G series mass flow controller (MFC) with the same O2 source was used for the N2 purge and higher compressed air flows (above 75 sccm). In some variations, the dissolved O2 content (mg / L) can also be measured via an in situ rugged dissolved oxygen (RDO) probe and a Thermo-Fischer Orion Star A216 meter for reactions carried out at low temperatures. This can provide additional quantitative and qualitative data from inside the reaction medium when used to monitor the headspace. Reactor contents of 3% or 3.4% solids were diluted in the ACOMP system 112 through two separate dilution steps to concentrations ranging from 0.4 mg / ml to 1.5 mg / ml in the detector row.

[0059] 2-10 show data for acrylamide (Am) free radical polymerization reactions initiated with potassium persulfate (KPS) at either 50°C or 65°C.

[0060] Figure 2 shows raw light scattering and UV absorption data for two acrylamide (Am) free radical reactions; the first was purged from the reactor with nitrogen (N2), and the second was initially purged with N2, and the reactor was then bled with air 10 minutes after the start of the reaction, which was continued for about 60 minutes. When O2 was bled, the reaction stopped when the O2 concentration reached a threshold value [O2]t, and the Am concentration [Am] remained at a finite plateau. At the conversion plateau, there was no further increase in light scattering, since no additional polymer was produced during the plateau. Due to the free radical polymerization of acrylamide, the reaction spontaneously restarts. The restart occurs rather abruptly, continuing to decrease the UV and increase the light scattering. The restart of the reaction occurs because the O2 in the reactor is removed by the catalytic process of Am. In this process, Am receives free radicals from the decay initiator and transfers them to O2, which then reacts with water or other substances and is removed. When loss of O2 reduces the O2 concentration to a threshold value [O2]t, the reaction spontaneously resumes.

[0061] FIG. 3 shows the concentration of dissolved O2 in the reactor as measured by the in situ RDO probe. The turn-off of the reaction with increasing O2 is seen at the beginning of the Am concentration plateau (CAm). The start and end of the 15 sccm flow rate of compressed air used for this reaction are indicated by separate circles 302 and 304. As shown, once O2 rises above a threshold value [O2]t, there is a plateau 306 in the Am concentration [Am] indicating that the reaction stops. After O2 falls below the threshold value, Am begins to decline from the plateau 306 at point 308.

[0062] FIG. 4 shows a comparison of the short and long conversion plateaus between the two air flow rates of 192 sccm and 15 sccm shown in FIG. 2 and FIG. 3. The mass concentration of Am monomer in the reactor (g / cm 3The conversion is shown in FIG. 4 as 192 sccm or 192 cm 3 Curve 402, representing a high air flow rate of 15 sccm or 15 cm, has a plateau in Am concentration. The air flow is stopped at time 401. After the air flow is stopped for a while, the O2 concentration decreases below the threshold [O2]t due to the catalytic process of Am, and the reaction spontaneously resumes as the Am concentration or [Am] starts to drop at time 403. Without O2, curve 404 shows that the Am concentration gradually drops without the presence of a plateau. Also, at 15 sccm or 15 cm 3 Curve 406, representing a low airflow rate of 100 / min, shows that some time after the airflow is stopped at time 405, the Am concentration begins to drop at time 407. After the airflow has been stopped for a period of time (e.g., about 500 seconds), the airflow decreases below the threshold [O2]t.

[0063] Curve 405 shows that the Am concentration at the low air flow rate of 15 sccm drops slower than curve 404 without oxygen, suggesting that small amounts of oxygen below the threshold [O2]t slow the reaction but do not stop it. Thus, when O2 removal reduces the concentration of O2 to the threshold [O2]t, the reaction spontaneously resumes, such as at time 403 or 407.

[0064] Figures 2-4 show how [O2]>[O2]t stops the reaction. However, for [O2]<[O2]t, this small amount of oxygen [O2] slows down the reaction but does not stop it, and furthermore, the M measured via Eq. w and the measured polymer concentration C p The cumulative weight average molecular weight M w and instantaneous weight average molecular weight M w,inst is significantly lower than the value for the reaction without O2.

[0065] Thus, O2 acts as a chain terminator for [O2]<[O2]t, shortening the polymer chains similarly to a chain transfer agent, and O2 can be utilized as a reversible chain terminator, which is a surprising discovery of the present disclosure. Small amounts of O2 below the threshold [O2]t can be used to reversibly control polymer reactions. While it is known to those skilled in the art that large amounts of oxygen can terminate a reaction, it is not known that small amounts of oxygen below the threshold can reversibly control a reaction. Because the flow of O2 can be carefully controlled, added, and removed as needed, O2 can be used for fine control of molecular weight trajectories. Furthermore, O2 can be added to the reaction at virtually any desired rate and can be quickly purged with an inert gas, giving great flexibility in application. O2 acts as a reversible chain terminator for [O2]<[O2]t. Conventional chemical chain transfer agents, such as sodium formate, cannot be easily removed once added to the reaction and are irreversible. Once a conventional chemical chain transfer agent is added, the chain transfer agent continues to shorten the polymer chains throughout the reaction, which reduces the molecular weight and reduces the viscosity.

[0066] FIG. 5 shows the concentration of polyacrylamide (pAm) derived from [Am] via mass balance for a reaction without O2 (curve 502) and a second reaction with 6 sccm air flow (curve 504). Again, curve 504 shows the effect of O2 on the reaction compared to curve 502 without O2. Specifically, at 6 sccm air flow, a conversion plateau 504A was reached, the reaction was restarted, and then 6 sccm air flow was restarted and a second conversion plateau 504B was reached. After restarting the reaction a second time, the remainder of the conversion 504C resembles the normal trajectory of the reaction without O2.

[0067] Figure 6 shows the M of the two reactions in Figure 5. w When the 6 sccm air flow begins, M w is significantly smaller than in a similar reaction without O2. This indicates the chain termination and shortening function when O2 is below [O2]t. 3 When the airflow is turned off, as shown by the line nearw The orbit is about 0.013g / cm 3 restores its non-O2 orbitals, at which point O2 is spontaneously eliminated, demonstrating the reversible nature of the chain-terminating effect of O2.

[0068] FIG. 7 shows the instantaneous weight average molecular weight M for the data in FIG. 6, calculated according to Equation 4. w,inst The chains produced during the air flow period before the plateau are much smaller than those produced in the absence of O2. The final part of the reaction occurs when the pAm concentration is 0.012 g / cm 3 Starting near M w,inst to close to the value for the reaction without O2. This further illustrates the reversible nature of O2 as a chain terminator: O2 shortens the chain below [O2]t, but no longer shortens the chain when O2 is removed.

[0069] Figure 8 shows the cumulative reduced viscosity (RV) obtained from a highly dilute sample stream. This non-optical measurement, performed using a single capillary pressure transducer, is p The RV in this limit is the intrinsic viscosity (IV) of the polymer, which is directly related to the molecular weight and hydrodynamic volume of the polymer and therefore provides an independent check of the chain termination and shortening effects. The cumulative RV behavior in Figure 8 is qualitatively similar to the cumulative light scattering behavior in Figure 5. We also demonstrated the reversibility of the chain termination and shortening effects of O2.

[0070] Figure 9 shows the calculated M w Substitute RV for RV inst RV with 6sccm air flow inst reflects the chain shortening effect found independently by light scattering, inst is less than.

[0071] Figures 7 and 9 also show the reversibility of the O2 chain termination effect. In both cases, M w,inst and RV instEach of these increases and decreases during the reaction, returning to the same value as in the reaction without O2 when the reactor is cleared of O2. This reversible nature of O2 as a chain terminator and shortener distinguishes it from conventional chain transfer agents (CTAs), which produce a higher M than without the CTA. w,inst This disclosure provides a method to reduce the risk of M w,inst can be raised or lowered. example

[0072] The following examples are for illustrative purposes only. It will be apparent to those skilled in the art that many modifications, both to materials and methods, may be practiced without departing from the scope of the disclosure. Example 1

[0073] The following non-limiting embodiment of automatic molecular weight control with variable O2 is a flow of O2 controlled by the control algorithm 106. w,inst This is a description of how the M w,inst The desired trajectory for M can be established versus either time or polymer concentration, which determines the final desired MWD. w Continuous monitoring of, for example, the ACOMP system 112 can be used to obtain a derived quantity M w,inst A typical reaction lasts for several hours. A control interval Δt is chosen, for example 60 seconds, and M w,inst The current value at (t) is compared to the value at the end of the control interval and the difference is then determined by Equation 6a as follows: TIFF2025507697000007.tif11138 (Formula 6a)

[0074] Difference ΔX w,inst (t+Δt) is calculated by Equation 6b as follows: w,inst can also be expressed as follows: TIFF2025507697000008.tif12165 (Formula 6b) where X represents any variable such as viscosity, composition, or branching, among others.

[0075] The means for determining the O2 flow, Q (in sccm or other convenient units), is the M w,inst The aim is to create a calibration curve of the effect of Q on . First, equation 1 is rewritten as equations 7a and 7b as follows: TIFF2025507697000009.tif29153 (Formula 7a) TIFF2025507697000010.tif28153 (Formula 7b)

[0076] where the O2 flow rate Q replaces [CTA] in Equation 1, and k3' has the inverse units of the flow rate Q (M w,inst =X w,inst * M and m are the molar masses of the monomers (g / mol).

[0077] For a given type of reaction, M w,inst The Q pairs are generated for some or all values ​​of [M] by conducting the reaction at several flow rates Q under certain desired conditions (temperature, initiator type, and concentration). w,inst The gradient of X is given by Equation 8. w,inst The incremental relationship between and Q is given as follows: TIFF2025507697000011.tif26163 (Formula 8)

[0078] This slope is empirically determined by running similar reactions at various flow rates Q, and can be calculated from Equation 6a as ΔM w,inst The change in flow rate ΔQ(t) set at the beginning of the control interval to achieve (t+Δt) is: TIFF2025507697000012.tif30138 (Formula 9)

[0079] The gradient becomes negative and decreases M w,inst will be positive. The above calculations can be included in the calculation algorithm in the calculation module 111 of the ACOMP system 112.

[0080] There are several ways to adjust the O2 flow to maintain the target trajectory, but one non-limiting method is by a calibration curve.

[0081] Figure 10 shows [KPS]= * 4.5e -4 g / cm 3 The slope calibration curve for Am at T = 50 °C is shown, with the slope in g-min / mol-cm. 3 For example, M w,inst (t) = 820,000 g / mol, with a given flow rate Q and [Am] = 0.025 g / cm 3 (polymer concentration [pAm]=[Am]0-[Am](t), where [Am] is measured directly by the ACOMP system 112). For target value=795,000. From FIG. 10, the slope is [Am]=0.025 g / cm 3 And, according to Equation 9, the air flow rate is 0.69 cm 3 It is estimated that the rate decreases by 1 / min.

[0082] In some variations, the slope of the calibration curve may change with temperature.

[0083] In some variations, the slope calibration curve may vary with, among other things, the type of initiator and the amount of initiator.

[0084] It will be understood by one of ordinary skill in the art that a slope calibration curve can be obtained for any polymer property X.

[0085] While the above demonstration used Am, the methods of this disclosure are not limited to Am and apply to many monomers and comonomers in both aqueous and organic phase reactions. For example, Figure 11 shows how flowing O2 below [O2]t successfully shortened chain termination of sodium styrene sulfonate (SS) free radical polymerization in water at 100 mM sodium chloride (NaCl) ionic strength.

[0086] 12 is a flow chart illustrating steps for controlling a polymerization reaction using the addition of oxygen according to an exemplary embodiment of the present disclosure. A method 1200 for controlling a polymerization reaction using the addition of oxygen includes providing a reactor including one or more chemical components suitable for promoting a polymerization reaction in operation 1202.

[0087] In some variations, the polymerization reaction is selected from the group consisting of a free radical reaction, a controlled free radical reaction, a living polymerization, a step-growth polymerization, a catalyst-assisted polymerization reaction, and any combination thereof.

[0088] The method 1200 also includes, in operation 1206, continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor.

[0089] In some variations, the method 1200 may also include continuous monitoring of the oxygen concentration within the reactor 102.

[0090] In some variations, the method 1200 may also include delivering an amount of oxygen to the reactor as determined by the control algorithm 106. Supplying oxygen to the reactor includes supplying by the controller 104 operable to automatically supply the amount of oxygen as determined by the control algorithm 106 to the reactor 102.

[0091] The method 1200 also includes using a control algorithm to determine an amount of oxygen to add to the reactor at one or more points during the polymerization reaction based on the continuously measured one or more polymer properties to cause the one or more polymer properties to follow a predetermined target trajectory in operation 1210.

[0092] In some variations, the one or more polymer properties may include weight average molecular weight.

[0093] In some variations, the one or more polymer properties may include instantaneous weight average molecular weight.

[0094] In some variations, the one or more polymer properties may include the reduced viscosity of the polymer.

[0095] In some variations, the one or more polymer properties may include instantaneous reduced viscosity.

[0096] In some variations, the one or more polymer properties may include the instantaneous composition of the copolymer.

[0097] In some variations, the method 1200 may also include using a control algorithm to determine, based on continuous measurements of one or more polymer properties, an amount of oxygen to add to the reactor to stop the polymerization reaction or slow the reaction rate by a predetermined amount.

[0098] In some variations, the method 1200 may also include introducing an inert gas into the reactor 102 to purge O 2 from the reactor.

[0099] In some variations, the method 1200 can also include modifying one or more additional control variables for the reactor 102. The one or more additional control variables are selected from the group consisting of temperature and addition of monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and chain transfer agents to the reaction.

[0100] In some variations, the method 1200 may also include reversibly controlling one or more polymer properties by controlling the concentration of oxygen.

[0101] In some variations, the method 1200 also includes controlling the concentration of oxygen to reduce the M w,inst The present invention may include reversibly controlling

[0102] In some variations, the method 1200 reduces the M w,inst This may include reducing

[0103] In some variations, the method 1200 reduces the M by decreasing the oxygen concentration. w,inst It may also include increasing

[0104] In some variations, the method 1200 may also include spontaneously restarting the reaction by ceasing the delivery of oxygen or air flow.

[0105] In some variations, oxygen is a reversible chain terminator and shortener.

[0106] In some variations, the oxygen concentration is below a threshold value [O2] to control the reaction.

[0107] Statement 1. a reactor in which the polymerization reaction occurs; a means for controlled delivery of oxygen to the reactor; and and means for continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor. Device.

[0108] Statement 2. the means for continuously measuring one or more polymer properties of the polymer comprises an Automatic Continuous Online Monitoring of Polymerization Reactions (ACOMP) system, the ACOMP system comprising means for continuously monitoring monomer and polymer concentrations in the reactor; The device described in statement 1.

[0109] Statement 3. The ACOMP system comprises: a processor configured to receive data from a means for continuously monitoring monomer and polymer concentrations in the reactor; and a calculation module configured to calculate one or more polymer properties of a polymer based on the data from the processor and generate a control algorithm. 3. An apparatus according to any one of statements 1 to 2.

[0110] Statement 4. A tangible, non-transitory computer-readable medium encoded with instructions that, when executed by a processor, and a non-transitory computer readable medium operative to use the control algorithm to determine an amount of oxygen to add to the reactor at one or more times during the polymerization reaction based on continuous measurements of the one or more polymer properties to cause the one or more polymer properties to follow a predetermined target trajectory. 4. An apparatus according to any one of statements 1 to 3.

[0111] Statement 5. the reactor includes a submerged oxygen sensor for continuously monitoring the concentration of oxygen; 5. An apparatus according to any one of statements 1 to 4.

[0112] Statement 6. the one or more polymer properties include weight average molecular weight; 6. An apparatus according to any one of statements 1 to 5.

[0113] Statement 7. the one or more polymer properties include instantaneous weight average molecular weight; 6. An apparatus according to any one of statements 1 to 5.

[0114] Statement 8. the one or more polymer properties include reduced viscosity of the polymer; 6. An apparatus according to any one of statements 1 to 5.

[0115] Statement 9. The one or more polymer properties include instantaneous reduced viscosity; 6. An apparatus according to any one of statements 1 to 5.

[0116] Statement 10. the one or more polymer properties include an instantaneous composition of the copolymer; 6. An apparatus according to any one of statements 1 to 5.

[0117] Statement 11. The oxygen is delivered to the reactor in gaseous form; 11. An apparatus according to any one of statements 1 to 10.

[0118] Statement 12. the means for controlled delivery of oxygen to the reactor comprises a controller operable to automatically deliver an amount of oxygen to the reactor determined by the control algorithm; 12. An apparatus according to any one of statements 1 to 11.

[0119] Statement 13. A tangible, non-transitory computer-readable medium encoded with instructions that, when executed by a processor, a non-transitory computer readable medium operative to use the control algorithm to determine, based on continuous measurements of the one or more polymer properties, the amount of oxygen to add to the reactor to stop or slow down the polymerization reaction. 13. An apparatus according to any one of statements 1 to 12.

[0120] Statement 14. the polymerization reaction is selected from the group consisting of a free radical reaction, a controlled free radical reaction, a living polymerization, a step-growth polymerization, a catalyst-assisted polymerization reaction, and any combination thereof; 14. An apparatus according to any one of statements 1 to 13.

[0121] Statement 15. the reactor comprising a means for introducing an inert gas to purge O2 from the reactor; 15. An apparatus according to any one of statements 1 to 14.

[0122] Statement 16. further comprising a means for controlled delivery of one or more additional control variables to the reactor; 16. An apparatus according to any one of statements 1 to 15.

[0123] Statement 17. the one or more additional control variables are selected from the group consisting of temperature, monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and addition of chain transfer agents to the reaction; The device referred to in statement 16.

[0124] Statement 18. The oxygen is a reversible chain terminator and shortener; 18. An apparatus according to any one of statements 1 to 17.

[0125] Statement 19. The concentration of oxygen is below the threshold [O2] for controlling the reaction; 19. An apparatus according to any one of statements 1 to 18.

[0126] Statement 20. 1. A method for controlling a polymerization reaction by varying oxygen, comprising the steps of: providing a reactor containing one or more chemical components suitable for promoting a polymerization reaction; continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor; and determining, using a control algorithm, an amount of oxygen to add to the reactor at one or more times during the polymerization reaction based on the continuously measured one or more polymer properties, which causes the one or more polymer properties to follow a predetermined target trajectory. method.

[0127] Statement 21. delivering an amount of oxygen to the reactor determined by the control algorithm. The method described in statement 20.

[0128] Statement 22. further comprising continuously monitoring the concentration of oxygen in the reactor. 22. The method according to any one of statements 20 to 21.

[0129] Statement 23. the one or more polymer properties include weight average molecular weight; 23. The method according to any one of statements 20 to 22.

[0130] Statement 24. the one or more polymer properties include instantaneous weight average molecular weight; 23. The method according to any one of statements 20 to 22.

[0131] Statement 25. the one or more polymer properties include reduced viscosity of the polymer; 23. The method according to any one of statements 20 to 22.

[0132] Statement 26. The one or more polymer properties include instantaneous reduced viscosity; 23. The method according to any one of statements 20 to 22.

[0133] Statement 27. the one or more polymer properties include an instantaneous composition of the copolymer; 23. The method according to any one of statements 20 to 22.

[0134] Statement 28. The oxygen is delivered to the reactor in gaseous form; 28. The method according to any one of statements 20 to 27.

[0135] Statement 29. delivering the oxygen to the reactor by a controller operable to automatically deliver an amount of the oxygen to the reactor determined by the control algorithm; 29. The method according to any one of statements 20 to 28.

[0136] Statement 30. and determining, using a control algorithm, based on continuous measurements of the one or more polymer properties, the amount of oxygen to add to the reactor to terminate the polymerization reaction or to slow the reaction rate by a predetermined amount. 30. The method according to any one of statements 20 to 29.

[0137] Statement 31. the polymerization reaction is selected from the group consisting of a free radical reaction, a controlled free radical reaction, a living polymerization, a step-growth polymerization, a catalyst-assisted polymerization reaction, and any combination thereof; The method according to any one of statements 20 to 30.

[0138] Statement 32. further comprising introducing an inert gas into the reactor to purge O2 from the reactor. 32. The method according to any one of statements 20 to 31.

[0139] Statement 33. further comprising varying one or more additional control variables for the reactor. 33. The method according to any one of statements 20 to 32.

[0140] Statement 34. the one or more additional control variables are selected from the group consisting of temperature and addition of monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and chain transfer agents to the reaction; The method described in statement 33.

[0141] Statement 35. and reversibly controlling the one or more polymer properties by controlling the concentration of oxygen. 35. The method according to any one of statements 20 to 34.

[0142] Statement 36. By controlling the concentration of oxygen, M w,inst Further comprising reversibly controlling 36. The method according to any one of statements 20 to 35.

[0143] Statement 37. By increasing the concentration of oxygen, M w,inst and further comprising reducing 37. The method according to any one of statements 20 to 36.

[0144] Statement 38. By reducing the concentration of oxygen, M w,inst and further comprising increasing 38. The method according to any one of statements 20 to 37.

[0145] Statement 39. and allowing the reaction to spontaneously resume by ceasing the delivery of the oxygen or air flow. 39. The method according to any one of statements 20 to 38.

[0146] Statement 40. The concentration of oxygen is below the threshold [O2] for controlling the reaction; 39. The method according to any one of statements 20 to 39.

[0147] Statement 41. the oxygen being a reversible chain terminator and shortener; 41. The method of any one of statements 20 to 40.

[0148] Any ranges cited herein are inclusive. The terms "substantially" and "about" used throughout this specification are used to describe and account for slight variations. For example, they can mean ±5% or less, such as ±2% or less, such as ±1% or less, such as ±0.5% or less, such as ±0.2% or less, such as ±0.1% or less, such as ±0.05% or less.

[0149] Although several embodiments have been described, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Moreover, in order to avoid unnecessarily obscuring the invention, a number of well-known processes and elements have not been described. Thus, the above description should not be construed as limiting the scope of the invention.

[0150] Those skilled in the art will appreciate that the embodiments of the present disclosure are taught by way of example and not by way of limitation. Thus, the subject matter contained in the above description or shown in the accompanying drawings should be construed as illustrative and not in a limiting sense. The following claims are intended to cover all the general and specific features described herein, as well as all descriptions of the scope of methods and systems that may be said to fall therebetween, as a matter of language.

Claims

1. a reactor in which the polymerization reaction occurs; a means for controlled delivery of oxygen to the reactor; and and means for continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor. Device.

2. the means for continuously measuring one or more polymer properties of the polymer comprises an automated continuous on-line monitoring of polymerization reactions (ACOMP) system, the ACOMP system comprising means for continuously monitoring monomer and polymer concentrations in the reactor; 2. The apparatus of claim 1.

3. The ACOMP system comprises: a processor configured to receive data from a means for continuously monitoring monomer and polymer concentrations in the reactor; and a calculation module configured to calculate one or more polymer properties of a polymer based on the data from the processor and generate a control algorithm.

3. Apparatus according to any one of claims 1 to 2.

4. A tangible, non-transitory computer-readable medium encoded with instructions that, when executed by a processor, and a non-transitory computer readable medium operative to use the control algorithm to determine an amount of oxygen to add to the reactor at one or more points during the polymerization reaction based on continuous measurements of the one or more polymer properties to cause the one or more polymer properties to follow a predetermined target trajectory.

4. Apparatus according to any one of claims 1 to 3.

5. the reactor includes a submerged oxygen sensor for continuously monitoring the concentration of oxygen; 5. Apparatus according to any one of claims 1 to 4.

6. the one or more polymer properties include weight average molecular weight; 6. Apparatus according to any one of claims 1 to 5.

7. the one or more polymer properties include instantaneous weight average molecular weight; 6. Apparatus according to any one of claims 1 to 5.

8. the one or more polymer properties include reduced viscosity of the polymer; 6. Apparatus according to any one of claims 1 to 5.

9. The one or more polymer properties include instantaneous reduced viscosity; 6. Apparatus according to any one of claims 1 to 5.

10. the one or more polymer properties include an instantaneous composition of the copolymer; 6. Apparatus according to any one of claims 1 to 5.

11. The oxygen is delivered to the reactor in gaseous form; 11. Apparatus according to any one of claims 1 to 10.

12. the means for controlled delivery of oxygen to the reactor comprises a controller operable to automatically deliver an amount of oxygen to the reactor determined by the control algorithm; 12. Apparatus according to any one of claims 1 to 11.

13. A tangible, non-transitory computer-readable medium encoded with instructions that, when executed by a processor, a non-transitory computer readable medium operative to use the control algorithm to determine, based on continuous measurements of the one or more polymer properties, the amount of oxygen to add to the reactor to stop or slow down the polymerization reaction.

13. Apparatus according to any one of claims 1 to 12.

14. the polymerization reaction is selected from the group consisting of a free radical reaction, a controlled free radical reaction, a living polymerization, a step-growth polymerization, a catalyst-assisted polymerization reaction, and any combination thereof; 14. Apparatus according to any one of claims 1 to 13.

15. The reactor is provided with O ２ means for introducing an inert gas to purge the 15. Apparatus according to any one of claims 1 to 14.

16. and further comprising means for controlled delivery of one or more additional control variables to said reactor.

16. Apparatus according to any one of claims 1 to 15.

17. the one or more additional control variables are selected from the group consisting of temperature, monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and addition of chain transfer agents to the reaction; 17. The apparatus of claim 16.

18. The oxygen is a reversible chain terminator and shortener; 18. Apparatus according to any one of claims 1 to 17.

19. The concentration of oxygen is the threshold value for controlling the reaction [O ２ ] is less than 19. Apparatus according to any one of claims 1 to 18.

20. 1. A method for controlling a polymerization reaction by varying oxygen, comprising the steps of: providing a reactor containing one or more chemical components suitable for promoting a polymerization reaction; continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor; and determining, using a control algorithm, an amount of oxygen to add to the reactor at one or more points during the polymerization reaction based on the continuously measured one or more polymer properties, which causes the one or more polymer properties to follow a predetermined target trajectory. method.

21. delivering an amount of oxygen to the reactor determined by the control algorithm.

21. The method of claim 20.

22. further comprising continuously monitoring the concentration of oxygen in the reactor.

22. The method according to any one of claims 20 to 21.

23. the one or more polymer properties include weight average molecular weight; 23. The method according to any one of claims 20 to 22.

24. the one or more polymer properties include instantaneous weight average molecular weight; 23. The method according to any one of claims 20 to 22.

25. the one or more polymer properties include reduced viscosity of the polymer; 23. The method according to any one of claims 20 to 22.

26. The one or more polymer properties include instantaneous reduced viscosity; 23. The method according to any one of claims 20 to 22.

27. the one or more polymer properties include an instantaneous composition of the copolymer; 23. The method according to any one of claims 20 to 22.

28. The oxygen is delivered to the reactor in gaseous form; 28. The method of any one of claims 20 to 27.

29. delivering the oxygen to the reactor by a controller operable to automatically deliver an amount of the oxygen to the reactor determined by the control algorithm; 29. The method of any one of claims 20 to 28.

30. and determining, using a control algorithm, based on continuous measurements of the one or more polymer properties, the amount of oxygen to add to the reactor to terminate the polymerization reaction or to slow the reaction rate by a predetermined amount.

30. The method of any one of claims 20 to 29.

31. the polymerization reaction is selected from the group consisting of a free radical reaction, a controlled free radical reaction, a living polymerization, a step-growth polymerization, a catalyst-assisted polymerization reaction, and any combination thereof; 31. The method of any one of claims 20 to 30.

32. The reactor is then cooled to room temperature. ２ further comprising introducing an inert gas into the reactor to purge the 32. The method of any one of claims 20 to 31.

33. further comprising varying one or more additional control variables for the reactor.

33. The method of any one of claims 20 to 32.

34. the one or more additional control variables are selected from the group consisting of temperature and addition of monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and chain transfer agents to the reaction; 34. The method of claim 33.

35. and reversibly controlling the one or more polymer properties by controlling the concentration of the oxygen.

35. The method of any one of claims 20 to 34.

36. By controlling the concentration of the oxygen, M ｗ,ｉｎｓｔ Further comprising reversibly controlling 36. The method of any one of claims 20 to 35.

37. By increasing the concentration of oxygen, M ｗ,ｉｎｓｔ and further comprising reducing 37. The method of any one of claims 20 to 36.

38. By reducing the concentration of oxygen, M ｗ,ｉｎｓｔ and further comprising increasing 38. The method of any one of claims 20 to 37.

39. and allowing the reaction to spontaneously resume by ceasing the delivery of the oxygen or air flow.

39. The method of any one of claims 20 to 38.

40. The concentration of oxygen is the threshold value for controlling the reaction [O ２ ] is less than 40. The method of any one of claims 20 to 39.

41. the oxygen being a reversible chain terminator and shortener; 41. The method of any one of claims 20 to 40.

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