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 of related applications (Cross-reference of related applications) This patent application claims the benefits under 35 U.S.C. § 119(e) of U.S. Patent Application No. 63 / 268,602, filed on 26 February 2022, entitled “Oxygen-based control of polymerization reactions,” which is incorporated herein by reference in its entirety. field

[0002] This disclosure broadly relates to methods for controlling polymerization reactions. In particular, this disclosure relates to the control of polymerization reactions using controlled oxygen addition. In some non-limiting examples, the methods of this disclosure may include methods for controlling the molecular weight and associated properties of polymer and / or copolymer compositions produced during a polymerization reaction by controlled oxygen addition. [Background technology]

[0003] background Many properties of polymer materials, such as tensile strength and processability, are due to the molecular weight of the constituent polymer molecules. Therefore, controlling the polymer molecular weight is the ability to determine the properties of the polymer product. Similarly, copolymerization allows two or more comonomers with different properties to be bonded together to produce new material properties. One example is the copolymerization of polybutadiene and styrene, which produces non-brittle, impact-resistant polystyrene. A pair or group of comonomers can be copolymerized to give the polymer product many desirable characteristics. When two types of incompatible monomers are copolymerized, self-assembled structures can be formed both in the bulk material and on the surface.

[0004] Several methods exist for controlling the molecular weight of a polymer during polymerization. These include the use of various temperatures, initiators, catalysts, and transfer agents. In semi-batch operations, the molecular weight and copolymer composition can be controlled by the monomer supply to the reactor. However, further methods for controlling the polymerization reaction are desirable. [Overview of the Initiative]

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

[0006] In another embodiment, a method is provided for controlling a polymerization reaction by changing the oxygen. This method may include providing a reactor containing one or more chemical components suitable for accelerating 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 the amount of oxygen to be added to the reactor at one or more time points during the polymerization reaction, based on the continuously measured one or more polymer properties, thereby causing the one or more polymer properties to follow a predetermined target trajectory.

[0007] Additional embodiments and features are partially described below and may become apparent to those skilled in the art by examining this specification or may be learned by practicing the disclosed subject matter. A further understanding of the nature and merits of this disclosure may be achieved by referring to the remainder of this specification and the drawings that form part of this disclosure. [Brief explanation of the drawing]

[0008] To illustrate how the advantages and features of this disclosure can be obtained, embodiments thereof shown in the accompanying drawings are referenced. Understanding that these drawings illustrate exemplary embodiments of this disclosure and should therefore not be considered limiting its scope, the principles of this specification will be described with further specificity and detail using the accompanying drawings.

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

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

[0011] [Figure 2] Figure 2 shows raw light scattering and ultraviolet absorption data against time in the reactor for two acrylamide (Am) free radical reactions according to exemplary embodiments of the present disclosure.

[0012] [Figure 3] Figure 3 shows data representing the concentration versus time of dissolved O2 (DO) in the reactor, measured by a DO probe in the reactor, according to an exemplary embodiment of the present invention.

[0013] [Figure 4] Figure 4 shows data illustrating a comparison between two airflow rates of 192 standard cubic centimeters / minute (sccm) and 15 sccm, as shown in Figures 2 and 3, in short and long conversion plateaus, according to exemplary embodiments of the present disclosure.

[0014] [Figure 5]Figure 5 shows data for the concentration of polyacrylamide (pAm) as a function of reaction time, obtained from the concentration of Am or [Am] via mass balance, for an O2-free reaction and a second reaction containing 6 sccm, according to exemplary embodiments of the present disclosure.

[0015] [Figure 6] Figure 6 shows data comparing the cumulative weight-average molecular weight Mw for the two reactions in Figure 5 according to exemplary embodiments of this disclosure.

[0016] [Figure 7] Figure 7 shows data representing the instantaneous weight-average molecular weight Mw,inst versus pAm concentrations for the data shown in Figure 6, calculated according to Equation 4, according to exemplary embodiments of the present disclosure.

[0017] [Figure 8] Figure 8 shows data representing the cumulative reduced viscosity (RV) obtained from a highly diluted sample stream as a function of pAm or [pAm] concentration, according to exemplary embodiments of the present disclosure.

[0018] [Figure 9] Figure 9 shows data representing the concentrations of RVinst versus pAm, calculated by Equation 4, using RV instead of Mw, according to an exemplary embodiment of the present disclosure.

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

[0020] [Figure 11]Figure 11 shows the Mw relative to the concentration of polystyrene sulfonate (pSS) or [pSS], the use of O2 to shorten the pSS chain via chain termination, and how far below the O2 threshold [O2]t the O2 flow must be to successfully shorten the chain termination of styrene sulfonate (SS) free radical polymerization in water at a NaCl ionic strength of 100 mM.

[0021] [Figure 12] Figure 12 is a flowchart showing the steps for controlling a polymerization reaction using the addition of oxygen according to an exemplary embodiment of the present disclosure. [Modes for carrying out the invention]

[0022] Detailed explanation This disclosure provides a method for controlling a polymerization reaction, which includes using a low, controlled level of oxygen (O2) as a reversible means of actively controlling the molecular weight. The composition of the copolymer can also be controlled with O2.

[0023] The molecular weight depends on several factors, including temperature, the type and concentration of the initiator, the concentration of the monomer, and the type of polymerization mechanism, such as step growth reactions including free radicals, controlled free radicals, or polycondensation. Chain transfer agents (CTAs) such as sodium formate for molecular weight control of polyacrylamides affect the instantaneous weight-average dynamic chain length X w,inst The kinetic chain length is shortened according to the basic free radical formula for (the weight-average number of monomers in the polymer chain). TIFF0007882966000001.tif35150 (Formula 1)

[0024] In the formula, light scattering is the cumulative weight-average molecular weight M w This results in the instantaneous weight-average molecular weight M w,inst Since this is calculated, the weight average is used. In Equation 1, 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 the 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 the value when both processes occur is between 1 and 2. The dimensionless constant d is the instantaneous polydispersity index M w / Mn. As [CTA] increases, the chain length X w,inst decreases. When CTA is an added chemical, [CTA] keeps the denominator constant approximately and the chain shortening effect is irreversible. M w,inst is related to X w,inst by simply multiplying the monomer molecular weight m (g / mol) by it; M w,inst = mX w,inst . For acrylamide, m = 71.08 g / mol.

[0025] If [CTA] can be controlled in Equation 1, X w,inst can be decreased by increasing [CTA] and increased by decreasing [CTA]. The present disclosure contemplates molecular oxygen O2 as a very flexible CTA whose value in the denominator [CTA] can be freely modulated. Although it is generally known that O2 inhibits the reaction, its practical use has generally been limited to adding air or an O2 burst to slow down or stop a runaway exothermic reaction. The low O2 concentration threshold [O2]t for stopping the reaction means that a small amount of O2 is used to stop the free radical reaction.

[0026] One reason why O2 has not been used as a CTA until now is that the O2 concentration required to completely halt free radical reactions is on the order of 0.1 mg / L, while the saturation of dissolved O2 at T=25°C is approximately 6.56 mg / L. This narrow O2 concentration "window" of less than [O2]t can be used for molecular weight control and as a means of fine control of low gas flow rates. Furthermore, by using continuous monitoring of molecular weight, monomer concentration, conversion rate, reduced viscosity, composition (in the case of copolymers), and other properties, both the chain termination effect and the control of the polymer molecular weight and associated properties, as well as the composition of the copolymer produced during polymerization reactions by controlled oxygen addition, can be observed.

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

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

[0029] System 100 also includes a controller 104 for controlling control variables 103, such as inert gas, oxygen concentration, temperature, monomer, initiator, catalyst, branching or crosslinking agent, chain transfer agent, and / or chain stopper. The controller 104 includes means for changing one or more additional control variables to the reactor.

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

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

[0032] The system 100 also includes a control algorithm 106 for controlling a control variable 103 via a controller 104. The control algorithm 106 is stored in a memory device or a tangible, non-temporary computer-readable medium. When the instruction is executed by the processor 108, the control algorithm 106 can be used to determine the amount of oxygen to add to the reactor at one or more time points during the polymerization reaction, based on a series of measurements of one or more polymer properties, thereby causing one or more polymer properties to follow a predetermined target trajectory.

[0033] System 100 also includes an automated continuous online monitoring (ACOMP) system 112 of polymerization reactions that produce the 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, among other things, a monitor 110 capable of monitoring monomer and polymer concentrations. For example, the monitor 110 provides means for continuously monitoring the concentrations of monomers and polymers in the reactor. The monitor 110 also provides means for continuously monitoring viscosity, such as a capillary viscometer. The monitor 110 also, among other things, the cumulative weight-average molecular weight M w The system provides a means for continuously monitoring the cumulative weight-average molecular weight M. For example, monitor 110 monitors the cumulative weight-average molecular weight M. w It may include a light scattering device that generates, while the instantaneous weight-average molecular weight M w,inst This 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 is configured to receive information from means for continuously monitoring the concentrations of monomers and polymers in the reactor.

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

[0037] The control algorithm 106 can specify which control variables 103 can be manually controlled by the operator and enable "computation-assisted active control". The control variables 103 are computation-based controllers and can be automatically controlled via a controller 104 that enables automatic active control.

[0038] The ACOMP system 112 may include a tangible, non-temporary, computer-readable medium having encoded instructions. When executed by the processor 108, the instructions can be operated using a control algorithm 106 to determine the amount of oxygen to add to the reactor to stop the polymerization reaction or to reduce the reaction rate, based on a series of measurements of one or more polymer properties.

[0039] As used herein, the term “polymer reaction” means any kind of chemical or physical reaction involving polymers in all its forms. This includes, but is not limited to, any kind 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, and causes chemical modification of polymers, such as impregnation of negatively and / or positively charged polymers, impregnation of polymers having acidic or basic properties, polymer linking, or the growth of polymers from nanoparticles or microparticles such as silica, metals such as silver or gold, gels, metal oxides such as titanium dioxide or clay, and causes the formation of reversible or irreversible supramolecular assemblies of polymers and other particles.

[0040] Any type of polymerization mechanism can be used for reactions that produce polymers from monomers. These include chain growth and step growth reactions. The former are free radical and controlled radical polymerization. Under controlled radical polymerization, methods such as ring-opening metathesis polymerization (ROMP), atom transfer radical polymerization (ATRP), reversible addition-cleavage chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP) have been found, but are not limited to these. Polymer reactions can occur in solution phases, bulk phases, and heterogeneous phases, such as micelles, emulsions, reverse emulsions, and dispersions. This includes metallocene-based chain growth, as used in polyolefins. Step growth includes polycondensation reactions, such as those used in the production of polypeptides, polynucleotides, polyimides, polyamides, and polyurethanes. As used herein, the term “inert gas” refers in all its forms to gases such as nitrogen (N2) and other nonreactive gases, 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 limit the types of polymer reactors, also called polymer reaction vessels, to which it applies. Polymer reactors can be small, less than a milliliter, or large, 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, sometimes called "semi-batch," capable of supplying reagents, 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 processing stages can occur at different points along the trajectory of the reaction fluid through the reactor. In a continuous stirred tank reactor, a steady state can be reached within the reactor, and multiple continuous stirred tank reactors (CSTRs) can be arranged in a 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, as well as related quantities such as monomers and polymer compositions, and to monitor these properties at a frequency sufficient to enable active control of polymer molecular weight. When the composition is controlled, it is useful to be able to distinguish and monitor the conversion process of the comonomers involved. Measurements can be performed at a sufficiently high frequency, in some cases, by monitor 110, which includes in-reactor spectroscopic probes such as Raman scattering and infrared (IR). Within the ACOMP system 112, comonomer identification is achieved by refractive index, ultraviolet absorption, near-infrared, infrared, and conductivity. When chiral molecules are mixed with achiral molecules, the former can be distinguished using a circular polarimeter or other optically active sensors such as circular dichroism or circular birefringence. Monitor 110, which includes nuclear magnetic resonance (NMR), can also be used in the ACOMP system 112 to distinguish comonomers. The ACOMP system is also called the ACOMP platform.

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

[0044] To implement active control of molecular weight, information on reaction characteristics can be used at a frequency sufficient to allow control operations to be performed at time intervals short compared to the reaction time. As used herein, the term “sufficient frequency” refers, in all its forms, to the frequency of data acquisition such that the control of the desired reaction characteristic is performed in a much shorter time than the time at which a substantial deviation of the controlled characteristic may occur. “Substantial deviation” depends on the degree to which the control is desired. For example, but not limited to, in some cases it may be acceptable to control the desired characteristic to within 35% of the model orbital, while in other cases it may be used to control the deviation to within 10%, within 5%, or even less than 1%. The sufficient frequency of reaction characteristic information is the frequency sufficient to control the characteristic within the desired boundary of deviation from the model orbital.

[0045] According to a non-limiting embodiment of the present invention, the ACOMP system 112 is M wMultiple reaction characteristics such as reduced viscosity, conversion rate, monomer and polymer concentrations, and comonomer compositions are measured once per second. Faster and slower rates can give general significance to frequency in reactions that typically last for tens of minutes or several hours. When the duration of data measurement (the reciprocal of frequency) is sufficiently within a timescale to control for deviation, such measurements are often referred to as "continuous," as in the term automated continuous online monitoring (ACOMP) of polymerization reactions. Manual sampling methods, such as those widely used in both polymer manufacturing and laboratories, rarely have frequencies high enough for active control. Similarly, online chromatography methods generally do not have sufficient frequency but can be used in this application.

[0046] Active control of one or more reaction variables during a reaction step can be achieved by one of three means provided by this disclosure. In “manual active control,” a human being has access to relevant characteristic data of a sufficient frequency range, and on that data, the human being follows a reaction trajectory for one or more relevant characteristics by manually controlling one or more processing control variables as described in the “control means” section. A control algorithm 106 indicates which control variables can be manually controlled by the operator, enabling “computation-assisted active control.” Finally, the processing control variables are automatically controlled via a computation-based controller 104, enabling automatic active control.

[0047] As used herein, the term “reaction orbital” refers in all its forms to a specific mathematical form of a reaction property, such as molecular weight (MW) or composition, versus a dependent variable. Common dependent variables in polymerization reactions are time and polymer or monomer concentration. Reaction orbitals can determine the final properties of a polymer, including its molecular weight and compositional distribution. In the case of copolymers, instantaneous compositional orbitals can determine its final compositional distribution. Therefore, the properties of the final polymer are controlled by controlling the reaction orbitals.

[0048] Here, using methods such as the ACOMP system 112, the cumulative weight-average molecular weight (M) can be measured frequently or continuously during polymer synthesis. w ) are examples, but are not limited to these; specific reaction characteristics can be considered. Let's consider a general characteristic X. By online monitoring of the reactor contents, the cumulative value of X in the reactor is X. c The result is obtained. The accumulation of X and the resulting distribution is the instantaneous value of X, i.e., X inst , and how much X in the cumulative population inst It depends on whether X is added. Specifically, c and X inst The relationship between these two is naturally given by equation 2, as follows. TIFF0007882966000002.tif50162 (Formula 2)

[0049] Here, C p X is the polymer concentration. inst (C p ) is derived from Equation 1, and the measured cumulative value X c (C p ) and C p Therefore, via Equation 3, we can obtain the following result. TIFF0007882966000003.tif35142 (Formula 3)

[0050] M w (C p ) can be measured directly from light scattering and concentration detectors in the ACOMP system. w,inst (C p ) is given by Equation 4 according to Equation 2 M w (C p It can be calculated from the ACOMP value of ). TIFF0007882966000004.tif45165 (Formula 4)

[0051] M w and C p From the primary ACOMP value, M w,instBy calculating this, we can display a histogram of the instantaneous mass-average (MWD) of the molecular weight distribution as the synthesis progresses. Up to this point, all quantities are based on primary detector measurements and are not independent of the model.

[0052] Similarly, N different copolymers, F inst,j The instantaneous composition of comonomer j in a copolymer having is given by formula 5. TIFF0007882966000005.tif23138 (Formula 5)

[0053] F inst,j This can be calculated from the concentration of each comonomer, dC p ,j=-dC m,j It is; that is, the monomer dC is negative. m,j The loss of polymer form C m,j It appears as an increase.

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

[0055] Figure 1B shows a non-limiting process flow diagram for controlling a polymerization reaction using controlled oxygen addition according to an exemplary embodiment of the present disclosure. As shown in Figure 1B, process 101 also includes a continuous analysis 103, which includes monitoring monomer and polymer concentrations by using a monitor 110 in step 105. The monitor 110 may also monitor other reaction properties, such as viscosity, among other things. The 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 This includes calculating ).

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

[0057] Process 101 also includes, in step 115, changing control variables 103 with respect to reactor 102. Control variables 103 include, among other things, one or more temperatures, as well as the addition of monomers, comonomers, initiators, catalysts, branching / crosslinking agents, chain transfer agents, and / or chain stoppers and shortening agents to the reaction. Process 101 also includes a polymer reaction in reactor 102 to produce a desired polymer.

[0058] For the results shown below, reactor 102 contained approximately 500 cubic centimeters (ccs) of aqueous reaction medium and approximately 100 ccs of headspace. Continuous reaction monitoring data was acquired using a Fluence Analytics third-generation ACOMP system 112. An Aalborg gas flow controller (GFC) with a flow rate of 0–10 sccm was used to introduce O2 into reactor 102 from a compressed air tank ultra-zero grade (approximately 20% O2). For N2 purging and higher compressed air flows (above 75 sccm), an MKS G-series mass flow controller (MFC) with the same O2 source was used. In some variations, dissolved O2 content (mg / L) can also be measured via a field-mounted 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 within the reaction medium when used to monitor headspace. The reactor content with 3% or 3.4% solids was diluted in the ACOMP system 112 to concentrations ranging from 0.4 mg / ml to 1.5 mg / ml in the detector row through two separate dilution steps.

[0059] Figures 2 to 10 show data for acrylamide (Am) free radical polymerization reactions initiated by 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, then air was flowed into the reactor 10 minutes after the start of the reaction and continued for approximately 60 minutes. When O2 was flowed, the reaction stopped when the O2 concentration reached the threshold [O2]t, and the Am concentration [Am] remained at a finite plateau. At the conversion plateau, there was no further increase in light scattering because 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 UV and increasing light scattering. The restart of the reaction occurs because the O2 in the reactor is removed by a 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 the O2 disappears and the O2 concentration drops to the threshold [O2]t, the reaction spontaneously restarts.

[0061] Figure 3 shows the concentration of dissolved O2 in the reactor as measured by an in-situ RDO probe. The turn-off of the reaction due to the increase in O2 is observed 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 in the figure, when O2 exceeds the threshold [O2]t, there is a plateau 306 at the Am concentration [Am], which indicates that the reaction stops. After O2 falls below the threshold, Am begins to decrease from plateau 306 at point 308.

[0062] Figure 4 shows a comparison of short and long conversion plateaus between two air flow rates of 192 sccm and 15 sccm, as shown in Figures 2 and 3. Mass concentration of Am monomer in the reactor (g / cm³) 3The conversion is shown in Figure 4. As shown, 192 sccm or 192 cm 3 Curve 402, representing a high airflow rate of / min, has a plateau at the Am concentration. The airflow stops at time 401. After the airflow has stopped for a while, the O2 concentration decreases to below the threshold [O2]t due to the catalytic process of Am, and the Am concentration or [Am] begins to decrease at time 403, so the reaction spontaneously restarts. In the absence of O2, curve 404 shows that the Am concentration gradually decreases without the presence of a plateau. Also, 15 sccm or 15 cm 3 Curve 406, representing a low airflow rate of / min, shows that after a period of time when the airflow is stopped at time 405, the Am concentration begins to decrease at time 407. After the airflow is stopped for a while (e.g., about 500 seconds), the airflow decreases to below the threshold [O2]t.

[0063] Curve 405 shows that the Am concentration at a low airflow rate of 15 sccm decreases more slowly than the oxygen-free curve 404, suggesting that small amounts of oxygen below the threshold [O2]t slow down the reaction but do not stop it. Therefore, when O2 removal reduces the O2 concentration to the threshold [O2], the reaction spontaneously restarts at time 403 or 407, etc.

[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, M measured via Equation 4 w and the measured polymer concentration C p The cumulative weight-average molecular weight M calculated from w and instantaneous weight-average molecular weight M w,inst This value is significantly lower than the value obtained in the reaction without O2.

[0065] Therefore, O2 acts as a chain arrester for [O2] < [O2]t, shortening the polymer chain as well as chain transfer agents, and O2 can be used as a reversible chain arrester, which is a remarkable discovery of this disclosure. Polymer reactions can be reversibly controlled using small amounts of O2 below the threshold [O2]t. While those skilled in the art know that large amounts of oxygen can halt a reaction, it is not known that small amounts of oxygen below the threshold can reversibly control the reaction. Since the flow of O2 can be carefully controlled, added, and removed as needed, O2 can be used for fine control of molecular weight orbitals. Furthermore, O2 can be virtually added to the reactants at any desired rate and can be rapidly purged with an inert gas, providing great flexibility in applications. O2 acts as a reversible chain arrester for [O2] < [O2]t. Conventional chemical chain transfer agents, such as sodium formate, are irreversible and cannot be easily removed once added to a reaction. Once a conventional chemical chain transfer agent is added, it continues to shorten the polymer chain throughout the reaction, which reduces molecular weight and viscosity.

[0066] Figure 5 shows the concentration of polyacrylamide (pAm) obtained from [Am] via the mass balance for the reaction without O2 (curve 502) and the second reaction with a 6 sccm airflow (curve 504). Again, curve 504 shows the effect of O2 on the reaction compared to curve 502 without O2. Specifically, with a 6 sccm airflow, the reaction reached conversion plateau 504A and restarted, and then with a restart of 6 sccm airflow, it reached the second conversion plateau 504B. After the second restart of the reaction, the remainder of 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 Let's compare them. When an airflow of 6 sccm starts, M w This is considerably smaller than in similar reactions without O2. This indicates chain termination and shortening when O2 falls below [O2]t. 0.01 g / cm 3 As shown by the nearby lines, when the airflow is turned off (blocked), Mw The orbital rate is approximately 0.013 g / cm³. 3 This restores the non--O2 orbital, and at that moment, O2 is spontaneously removed. This demonstrates the reversible nature of the O2 chain termination effect.

[0068] Figure 7 shows the instantaneous weight-average molecular weight M for the data in Figure 6, calculated according to Equation 4. w,inst This shows that the chains generated during the airflow period before the plateau are much smaller than the chains generated in the absence of O2. The final part of the reaction occurs when the pAm concentration is 0.012 g / cm³. 3 Starting from the vicinity, M w,inst This brings the reaction value close to that without O2. This further illustrates the reversible nature of O2 as a chain termination agent. O2 shortens the chain below [O2]t, but it no longer shortens the chain when O2 is removed.

[0069] Figure 8 shows the cumulative reduced viscosity (RV) obtained from a highly diluted sample stream. This non-optical measurement, performed using a single capillary pressure transducer, is low C p The RV at the limit is the intrinsic viscosity (IV) of the polymer, which is directly related to the polymer's molecular weight and hydrodynamic volume, thus providing an independent check for chain termination and shortening effects. The behavior of the cumulative RV in Figure 8 is qualitatively similar to the cumulative light scattering behavior in Figure 5. It also demonstrates the reversibility of chain termination and the shortening effect of O2.

[0070] Figure 9 is calculated by Equation 4, M w Substitute RV into RV inst This shows the RV of a 6 sccm airflow. inst This reflects the chain shortening effect independently observed by light scattering, RV inst It 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 or decreases during the reaction, and returns to the same value as the reaction without O2 when O2 is removed from the reactor. This reversible property of O2 as a chain arrester and shortening agent differs from that of conventional chain transfer agents (CTAs). Conventional chain transfer agents are more efficient than those without CTAs. w,inst By reducing the amount, it is usually not possible to reverse unless the CTA is removed or destroyed in some way. In this disclosure, O2 is carefully controlled to M w,inst It can be raised and lowered. example

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

[0073] The following non-limiting embodiment of automated molecular weight control using variable O2 is one in which the controlled flow of O2 is controlled by control algorithm 106. w,inst This explains how it can be modulated. w,inst The desired trajectory for M can be established with respect to either time or polymer concentration, which determines the final desired MWD. w The continuous monitoring of the derived quantity M is available, for example, by the ACOMP system 112. w,inst This results in a typical reaction lasting several hours. A control interval Δt is selected, for example, 60 seconds, and M at time t during the reaction. w,inst The current value of (t) is compared with the value at the end of the control interval, and the difference is then determined by equation 6a as follows: TIFF0007882966000006.tif11138 (Formula 6a)

[0074] Difference ΔX w,inst (t+Δt) is given by equation 6b, X w,inst Regarding this, it can also be expressed as follows: TIFF0007882966000007.tif12165 (Formula 6b) In the formula, X represents any variable, such as viscosity, composition, or branching.

[0075] The means for determining the O2 flow, flow rate Q (sccm or other convenient unit), is M at any monomer concentration [Am]. w,inst The objective is to create a calibration curve for the effect of Q on . First, rewrite equation 1 as equations 7a and 7b as follows. TIFF0007882966000008.tif29153 (Formula 7a) TIFF0007882966000009.tif28153 (Formula 7b)

[0076] In the formula, the O2 flow rate Q is replaced by [CTA] in formula 1, and k3' has the inverse unit of the flow rate Q (M w,inst =X w,inst * M and m are the molar masses (g / mol) of the monomer.

[0077] For a given type of reaction, M w,inst A counter for Q is created for some or all values ​​of [M] by carrying out the reaction at several flow rates Q under certain desired conditions (temperature, type of initiator, 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: TIFF0007882966000010.tif26163 (Formula 8)

[0078] This gradient is empirical and determined by performing similar reactions with various flow rates and Q values. Then, from equation 6a, ΔM w,inst To achieve (t+Δt), the initial flow rate change ΔQ(t) set for the control interval is as follows: TIFF0007882966000011.tif30138 (Formula 9)

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

[0080] There are several ways - not limited to one - to adjust the O2 flow to maintain the target orbit, one of which is by a calibration curve.

[0081] Figure 10 shows * 4.5e -4 g / cm 3 the gradient calibration curve of Am at T = 50°C, where the unit of the gradient is g-min / mol-cm 3 For example, M w,inst (t) = 820,000 g / mol, and for a given flow rate Q and [Am] = 0.025 g / cm 3 (where the polymer concentration [pAm] = [Am]0 - [Am](t), and [Am] is directly measured by the ACOMP system 112). When the target value = 795,000. From Figure 10, the gradient is -36,200 at [Am] = 0.025 g / cm 3 . And according to Equation 9, it is determined that the air flow rate decreases by 0.69 cm 3 / min.

[0082] In some variations, the gradient calibration curve can change with temperature.

[0083] In some variations, the gradient calibration curve can change especially depending on the type of initiator and the amount of initiator.

[0084] Those skilled in the art will understand that the gradient calibration curve can be obtained for any polymer property X.

[0085] The above demonstration used Am, but the method of the present disclosure is not limited to Am and is applicable to many monomers and comonomers in both aqueous and organic phase reactions. For example, Figure 11 shows how successful the flow of O2 below [O2]t was in shortening the chain termination of the free radical polymerization of sodium styrene sulfonate (SS) in water at an ionic strength of 100 mM sodium chloride (NaCl).

[0086] Figure 12 is a flowchart showing the steps for controlling a polymerization reaction using the addition of oxygen according to an exemplary embodiment of the present disclosure. Method 1200 for controlling a polymerization reaction using the addition of oxygen includes providing a reactor containing one or more chemical components suitable for promoting the polymerization reaction in operation 1202.

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

[0088] 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, method 1200 may also include continuous monitoring of the oxygen concentration in reactor 102.

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

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

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

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

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

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

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

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

[0098] In some variations, method 1200 may also include introducing an inert gas into the reactor to purge O2 from reactor 102.

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

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

[0101] In some variations, method 1200 also controls the oxygen concentration by M w,inst This may include reversibly controlling it.

[0102] In some variations, method 1200 increases the oxygen concentration by M w,inst This may include reducing it.

[0103] In some variations, method 1200 reduces the oxygen concentration by M w,inst This can also include increasing it.

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

[0105] In some variations, oxygen acts as a reversible chain arrester and shortening agent.

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

[0107] Statement 1. A reactor in which polymerization reactions occur internally, Means for controlled delivery of oxygen to the reactor, The system includes 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 includes an automated continuous online monitoring (ACOMP) system for polymerization reactions, the ACOMP system comprising means for continuously monitoring the concentrations of monomers and polymers in the reactor. The apparatus described in Statement 1.

[0109] Statement 3. The ACOMP system described above is A processor configured to receive data from means for continuously monitoring the concentrations of monomers and polymers in the reactor, The system further comprises a computing module configured to calculate one or more polymer properties of a polymer and generate a control algorithm based on the data from the processor. The apparatus described in any one of statements 1 or 2.

[0110] Statement 4. A tangible, non-temporary, computer-readable medium on which instructions are encoded, wherein the instructions, when executed by a processor, The system further comprises a non-temporary computer-readable medium that, using the control algorithm, determines the amount of oxygen to be added to the reactor at one or more time points during the polymerization reaction based on continuous measurement of the one or more polymer properties, and operates to cause the one or more polymer properties to follow a predetermined target trajectory. The apparatus described in any one of statements 1 through 3.

[0111] Statement 5. The reactor includes an immersion oxygen sensor for continuously monitoring the oxygen concentration. The apparatus described in any one of statements 1 through 4.

[0112] Statement 6. The one or more polymer properties include, The apparatus described in any one of statements 1 through 5.

[0113] Statement 7. The one or more polymer properties include instantaneous weight-average molecular weight, The apparatus described in any one of statements 1 through 5.

[0114] Statement 8. The one or more polymer properties include the reduced viscosity of the polymer. The apparatus described in any one of statements 1 through 5.

[0115] Statement 9. The one or more polymer properties include instantaneous reduction viscosity, The apparatus described in any one of statements 1 through 5.

[0116] Statement 10. The one or more polymer properties include the instantaneous composition of the copolymer. The apparatus described in any one of statements 1 through 5.

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

[0118] Statement 12. The means for controlled delivery of oxygen to the reactor comprises a controller that can operate to automatically deliver an amount of oxygen determined by the control algorithm to the reactor. The apparatus described in any one of statements 1 through 11.

[0119] Statement 13. A tangible, non-temporary, computer-readable medium on which instructions are encoded, wherein the instructions, when executed by a processor, The system further comprises a non-temporary computer-readable medium that operates using the control algorithm to determine the amount of oxygen to be added to the reactor in order to stop the polymerization reaction or reduce the reaction rate, based on the continuous measurement of one or more polymer properties. The apparatus described in any one of statements 1 through 12.

[0120] Statement 14. The polymerization reaction is selected from the group consisting of free radical reactions, controlled free radical reactions, living polymerization, step growth polymerization, catalyst-assisted polymerization, and any combination thereof. The apparatus described in any one of statements 1 through 13.

[0121] Statement 15. The reactor is equipped with means for introducing an inert gas to purge O2 from the reactor. The apparatus described in any one of statements 1 through 14.

[0122] Statement 16. The system further comprises means for the controlled delivery of one or more additional control variables to the reactor. The apparatus described in any one of statements 1 through 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 chain transfer agents added to the reaction. The apparatus described in Statement 16.

[0124] Statement 18. The oxygen is a reversible chain arrester and a chain shortening agent. The apparatus described in any one of statements 1 through 17.

[0125] Statement 19. The oxygen concentration is less than the threshold [O2] for controlling the reaction. The apparatus described in any one of statements 1 through 18.

[0126] Statement 20. A method for controlling polymerization reactions by changing the oxygen, To provide a reactor containing one or more chemical components suitable for promoting polymerization reactions, The process involves continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor, This includes determining, using a control algorithm, the amount of oxygen to be added to the reactor at one or more time points during the polymerization reaction based on one or more polymer properties that have been continuously measured, thereby causing the one or more polymer properties to follow a predetermined target trajectory. method.

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

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

[0129] Statement 23. The one or more polymer properties include, The method described in any one of statements 20 to 22.

[0130] Statement 24. The one or more polymer properties include instantaneous weight-average molecular weight, The method described in any one of statements 20 to 22.

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

[0132] Statement 26. The one or more polymer properties include instantaneous reduction viscosity, The method described in any one of statements 20 to 22.

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

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

[0135] Statement 29. The delivery of oxygen to the reactor includes delivery by a controller that is capable of automatically delivering the amount of oxygen determined by the control algorithm to the reactor. The method described in any one of statements 20 to 28.

[0136] Statement 30. The method further includes using a control algorithm to determine the amount of oxygen to be added to the reactor in order to stop the polymerization reaction or to reduce the reaction rate by a predetermined amount, based on the continuous measurement of one or more polymer properties. The method described in any one of statements 20 to 29.

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

[0138] Statement 32. The further step includes introducing an inert gas into the reactor in order to purge O2 from the reactor. The method described in any one of statements 20 to 31.

[0139] Statement 33. Further comprising changing one or more additional control variables for the reactor, The method described in 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 the 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. Further comprising reversibly controlling the one or more polymer properties by controlling the concentration of the oxygen, The method according to any one of Statements 20 to 34.

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

[0143] Statement 37. Further comprising decreasing M by increasing the concentration of the oxygen, w,inst The method according to any one of Statements 20 to 36.

[0144] Statement 38. Further comprising increasing M by decreasing the concentration of the oxygen, w,inst The method according to any one of Statements 20 to 37.

[0145] Statement 39. Further comprising spontaneously restarting the reaction by stopping the delivery of the oxygen or air flow, The method according to any one of Statements 20 to 38.

[0146] Statement 40. The concentration of the oxygen is less than the threshold value [O2] for controlling the reaction, The method according to any one of Statements 20 to 39.

[0147] Statement 41. The oxygen is a reversible chain terminator and a shortening agent, The method described in any one of statements 20 to 40.

[0148] Any scope referenced herein is inclusive. The terms “substantially” and “about” as used herein are used to describe and explain small variations. For example, they may mean ±5% or less, e.g., ±2% or less, e.g., ±1% or less, e.g., ±0.5% or less, e.g., ±0.2% or less, e.g., ±0.1% or less, e.g., ±0.05% or less.

[0149] While several embodiments have been described, it will be recognized by those skilled in the art that various modifications, alternative configurations, and equivalents can be used without departing from the spirit of the invention. Furthermore, many well-known processes and elements have not been described in order to avoid unnecessarily obscuring the invention. Therefore, the above description should not be construed as limiting the scope of the invention.

[0150] Those skilled in the art will understand that the embodiments of this disclosure are taught as examples and not as limitations. Accordingly, the subject matter included in the above description or shown in the accompanying drawings should be interpreted as illustrative and not as limiting. The following claims are intended to encompass all general and specific features described herein, as well as all descriptions of the scope of methods and systems, which, as a matter of language, may be said to fall between them.

Claims

1. A reactor in which polymerization reactions occur internally, Means for controlled delivery of oxygen to the reactor, A means for continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor, A tangible, non-temporary, computer-readable medium on which instructions are encoded, wherein, when executed by a processor, the instructions operate to determine the amount of oxygen to be added to or removed from the reactor at one or more time points during the polymerization reaction, based on a series of measurements of the one or more polymer properties. A controller configured to control the delivery of the oxygen to be below a threshold, wherein the oxygen reversibly controls one or more polymer properties, including one or more of M w, inst, instantaneous reduced viscosity (RV inst), and instantaneous composition of the copolymer, by adjusting the amount of oxygen to be below a threshold, and the adjustment includes adding oxygen to increase the oxygen concentration and purging oxygen to decrease the oxygen concentration. Device.

2. The means for continuously measuring one or more polymer properties of the polymer includes an automated continuous online monitoring (ACOMP) system for polymerization reactions, the ACOMP system comprising means for continuously monitoring the concentrations of monomers and polymers in the reactor. The apparatus according to claim 1.

3. The aforementioned automated continuous online monitoring (ACOMP) system is: A processor configured to receive data from means for continuously monitoring the concentrations of monomers and polymers in the reactor, The system further comprises a computing module configured to calculate one or more polymer properties of a polymer and generate a control algorithm based on the data from the processor. The apparatus according to claim 2.

4. A tangible, non-temporary, computer-readable medium on which instructions are encoded, wherein the instructions, when executed by a processor, The system further comprises a non-temporary computer-readable medium that, using the control algorithm, determines the amount of oxygen to be added to the reactor at one or more time points during the polymerization reaction based on continuous measurement of one or more polymer properties, and operates to cause the one or more polymer properties to follow a predetermined target trajectory. The apparatus according to claim 3.

5. The reactor includes an immersion oxygen sensor for continuously monitoring the oxygen concentration. The apparatus according to claim 1.

6. The one or more polymer properties include weight-average molecular weight, The apparatus according to claim 1.

7. The one or more polymer properties include instantaneous weight-average molecular weight, The apparatus according to claim 1.

8. The one or more polymer properties include the reduced viscosity of the polymer. The apparatus according to claim 1.

9. The one or more polymer properties include instantaneous reduction viscosity, The apparatus according to claim 1.

10. The one or more polymer properties include the instantaneous composition of the copolymer. The apparatus according to claim 1.

11. The oxygen is delivered to the reactor in gaseous form. The apparatus according to claim 1.

12. The controller is capable of automatically delivering the amount of oxygen determined by the control algorithm to the reactor. The apparatus according to claim 3.

13. The polymerization reaction is selected from the group consisting of free radical reactions, controlled free radical reactions, living polymerization, step growth polymerization, catalyst-assisted polymerization, and any combination thereof. The apparatus according to claim 1.

14. The reactor is from the reactor O ２ It includes means for introducing an inert gas to purge, The apparatus according to claim 1.

15. The system further comprises means for the controlled delivery of one or more additional control variables to the reactor. The apparatus according to claim 1.

16. The one or more additional control variables are selected from the group consisting of temperature, monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and chain transfer agents added to the polymerization reaction. The apparatus according to claim 15.

17. The oxygen is a reversible chain arrester and a chain shortening agent. The apparatus according to claim 1.

18. A method for controlling polymerization reactions by changing the oxygen, To provide a reactor containing one or more chemical components suitable for promoting polymerization reactions, The process involves continuously measuring one or more polymer properties of the polymer produced by the polymerization reaction in the reactor, Using a control algorithm, determine the amount of oxygen to be added to or removed from the reactor at one or more time points during the polymerization reaction, based on one or more polymer properties that have been continuously measured. The amount of oxygen determined by the control algorithm is delivered to the reactor, The oxygen concentration inside the reactor is to be measured continuously, The method includes controlling the oxygen concentration to be below a threshold in order to reversibly control one or more polymer properties, including one or more of M w, inst, instantaneous reduced viscosity (RV inst), and instantaneous composition of the copolymer, by adjusting the amount of oxygen to be below a threshold, wherein the adjustment includes adding oxygen to increase the oxygen concentration and purging oxygen to decrease the oxygen concentration. method.

19. The one or more polymer properties include weight-average molecular weight, The method according to claim 18.

20. The one or more polymer properties include instantaneous weight-average molecular weight, The method according to claim 18.

21. The one or more polymer properties include the reduced viscosity of the polymer. The method according to claim 18.

22. The one or more polymer properties include instantaneous reduction viscosity, The method according to claim 18.

23. The one or more polymer properties include the instantaneous composition of the copolymer. The method according to claim 18.

24. The oxygen is delivered to the reactor in gaseous form. The method according to claim 18.

25. The delivery of oxygen to the reactor includes delivery by a controller that is capable of automatically delivering the amount of oxygen determined by the control algorithm to the reactor. The method according to claim 18.

26. The control algorithm further includes determining the amount of oxygen to be added to the reactor in order to stop the polymerization reaction or to reduce the reaction rate by a predetermined amount, based on the continuous measurement of one or more polymer properties. The method according to claim 18.

27. The polymerization reaction is selected from the group consisting of free radical reactions, controlled free radical reactions, living polymerization, step growth polymerization, catalyst-assisted polymerization, and any combination thereof. The method according to claim 18.

28. From the reactor O ２ Further includes introducing an inert gas into the reactor in order to purge, The method according to claim 18.

29. Further includes changing one or more additional control variables for the reactor, The method according to claim 18.

30. The one or more additional control variables are selected from the group consisting of temperature and the addition of monomers, comonomers, initiators, catalysts, branching / crosslinking agents, and chain transfer agents to the polymerization reaction. The method according to claim 29.

31. By increasing the concentration of the oxygen, ｗ,ｉｎｓｔ Further including reducing The method according to claim 18.

32. By reducing the concentration of the oxygen, ｗ,ｉｎｓｔ Further including increasing The method according to claim 18.

33. The further includes spontaneously restarting the polymerization reaction by stopping the delivery of the oxygen or airflow, The method according to claim 18.

34. The oxygen is a reversible chain arrester and shortening agent. The method according to claim 18.

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