Synthesis of polyurethane polymer in a flow reactor

Abstract

Provided is a technique for the polymerization of polyurethane. For example, one or more embodiments described herein can include synthesizing polyurethane by a polymerization reaction carried out in a flow reactor. The polymerization reaction can polymerize a diol with a diisocyanate.

Description

[Technical Field]

[0001] The present disclosure relates to the synthesis of polyurethane polymers in one or more flow reactors, and more particularly to polyurethane polymerization schemes that can be run autonomously in one or more computer-controlled flow reactors. Summary of the Invention [Means for solving the problem]

[0002] The following presents a summary intended to provide a basic understanding of one or more embodiments of the present invention. This summary is not intended to identify key or critical elements or to delineate the scope of particular embodiments or claims. Its sole purpose is to present concepts in a simplified form as a prelude to the more detailed description presented later. In one or more embodiments described herein, polymer synthesis, computer-implemented methods, systems, computer program products, or combinations thereof, are described, which may involve the synthesis of polyurethanes in one or more flow reactors.

[0003] According to one embodiment, a method is provided that includes synthesizing a polyurethane by a polymerization reaction carried out in a flow reactor, the polymerization reaction polymerizing a diol with a diisocyanate.

[0004] According to one embodiment, a computer-implemented method is provided that can include measuring, by a system operatively coupled to a processor, reactant conversion of a polyurethane polymerization reaction in a flow reactor, and adjusting, by the system, flow rates of chemical reactants in the flow reactor based on the measurement to achieve a target polyurethane structure.

[0005] According to one embodiment, a system is provided. The system can include a flow reactor capable of performing a polyurethane polymerization reaction. The system can further include a measurement device capable of determining a reaction rate value of a reactant in the polyurethane polymerization reaction in the flow reactor. The system can also include a computing device that controls the polyurethane polymerization reaction based on the reaction rate value of the reactant by adjusting the flow rate in the flow reactor. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is an exemplary, non-limiting polymerization scheme for the synthesis of polyurethane in one or more flow reactors according to one or more embodiments described herein. [Figure 2] FIG. 2 is an exemplary, non-limiting polymerization scheme for the synthesis of polyurethane in one or more flow reactors controlled by one or more autonomous computer systems, according to one or more embodiments described herein. [Figure 3] FIG. 3 is an exemplary, non-limiting graph illustrating reaction rates of chemical reactants associated with one or more polymerization schemes for the synthesis of polyurethane in one or more flow reactors according to one or more embodiments described herein. [Figure 4] FIG. 4 is an exemplary, non-limiting graph of a Fourier transform infrared (“FTIR”) spectrum that can characterize reaction conditions within one or more flow reactors according to one or more embodiments described herein. [Figure 5] FIG. 5 is an exemplary, non-limiting control scheme that may be employed by one or more reactor control systems to modify one or more polyurethane polymerization reactions in one or more flow reactors, according to one or more embodiments described herein. [Figure 6]FIG. 6 is an exemplary, non-limiting control scheme that may be employed by one or more reactor control systems to modify one or more polyurethane polymerization reactions in one or more flow reactors according to one or more embodiments described herein. [Figure 7] FIG. 7 is an exemplary, non-limiting polymerization scheme in which one or more macrodiols can be synthesized in a first section of a flow reactor and fed to a second section of the flow reactor for further synthesis of one or more polyurethanes, according to one or more embodiments described herein. [Figure 8] FIG. 8 is an exemplary, non-limiting polymerization scheme that may be controlled by an autonomous computing system to synthesize one or more macrodiols in a first portion of a flow reactor, or one or more polyurethanes in a second portion of a flow reactor, or a combination thereof, according to one or more embodiments described herein. [Figure 9] FIG. 9 is an exemplary, non-limiting polymerization scheme that may be controlled by an autonomous computing system to synthesize one or more macrodiols in a first portion of a flow reactor, or one or more end-capped polyurethanes in a second portion of a flow reactor, or a combination thereof, according to one or more embodiments described herein. [Figure 10] FIG. 10 shows an exemplary, non-limiting graph illustrating the reaction rates of chemical reactants associated with one or more polymerization schemes for the synthesis of HEMA-endcapped polyurethane in one or more flow reactors according to one or more embodiments described herein. [Figure 11] FIG. 11 illustrates a flow diagram of an exemplary, non-limiting computer-implemented method that may be employed by one or more reactor control systems in accordance with one or more embodiments described herein. [Figure 12] FIG. 12 illustrates a block diagram of an exemplary, non-limiting operating environment in which one or more embodiments described herein may be facilitated. DETAILED DESCRIPTION OF THE INVENTION

[0007] The following detailed description is merely exemplary and is not intended to limit the embodiments, their application or uses, or combinations thereof. Furthermore, there is no intention to be bound by any express or implied information presented in the preceding "Background" or "Summary" sections or in the "Detailed Description" section.

[0008] One or more embodiments will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a more thorough understanding of one or more embodiments. It will be apparent, however, that in various instances, one or more embodiments may be practiced without these specific details.

[0009] The synthesis of polyurethanes by step-growth polymerization allows the material properties of the polymer to be tailored to the desired application by selecting the starting materials, composition, post-treatment, or a combination thereof. However, stoichiometric imbalance, high reactivity of isocyanate groups, exothermic polymerization processes, or a combination thereof can cause batch-to-batch variability and secondary reactions, reducing control of polymerization, material quality, molecular weight characteristics, and reproducibility.

[0010] Various embodiments described herein relate to the use of flow reactors for the synthesis of polyurethanes. Furthermore, one or more embodiments described herein may employ integration of a flow reactor with in-line analysis, real-time process control, or a combination thereof. For example, one or more embodiments described herein may include the synthesis of a segmented linear polyurethane, which may comprise a composition of hard and soft segments distributed along the polymer backbone. The hard segments may be derived from low-molecular-weight monomers (e.g., diisocyanate monomers, diol monomers, or combinations thereof) to generate urethane groups. Consequently, the short intramolecular distance between urethane moieties along the polymer backbone allows for relatively strong interactions, along with the ability for intermolecular hydrogen bonding, to form crystalline domains. The soft segments may be derived from higher molecular weight diols (e.g., polymeric diols with glass transition temperatures below ambient levels). Furthermore, the soft segments may be amorphous and integrated into the polymer backbone. In various embodiments, 4,4'-methylenediphenyldiisocyanate ("MDI") may be employed as the diisocyanate monomer. Also, low molecular weight 1,6-hexanediol ("HDO"), as well as polymeric diols based on polyethylene glycol ("PEG") and polycaprolactone, can be employed as diol equivalents. One or more embodiments can further use an organic or organometallic catalyst (e.g., dibutyltin dilaurate ("DBTDL") or a combination thereof, 1,8-diazabicyclo[5.4.0]undec-7-ene ("DBU"), or a combination thereof, to facilitate the polymerization.

[0011] In one or more embodiments, polyurethane polymerization can be carried out in one or more flow reactors. As used herein, the term "flow reactor" can refer to a device in which one or more chemical reactions can occur within one or more channels (e.g., microfluidic channels), such as tubing having an internal diameter of 0.1 to 1 millimeter (mm). For example, a flow reactor can facilitate continuous flow production, as opposed to batch production. One or more streams of chemical reactants can flow (e.g., continuously) through one or more channels of the flow reactor, where one or more chemical reactions involving the chemical reactants (e.g., polymerization, protonation, deprotonation, or a combination thereof) can occur within the one or more channels as the one or more streams flow. In various embodiments, the polymerizations described herein can be carried out in one or more flow reactors at room temperature or elevated temperatures, with residence times ranging from, for example, milliseconds (e.g., with high activity catalysts, elevated temperatures, or a combination thereof) to minutes, and flow rates ranging from, for example, 1 microliter / minute (μL / min) or more to 100 milliliters / second (mL / s) or less.

[0012] In one or more embodiments, one or more flow reactors employed to carry out polyurethane synthesis can include one or more sensors, measurement devices, proportional-integral-derivative ("PID") controllers, or combinations thereof. Additionally, one or more flow reactors can be coupled to one or more reactor control systems. In various embodiments, the one or more reactor control systems can autonomously control the one or more flow reactors to synthesize a target polyurethane. For example, the one or more reactor control systems can control the amount, concentration, or combination of chemical reactants and / or catalysts introduced into the one or more flow reactors by adjusting one or more flow rates. The one or more reactor control systems can also monitor the structure, properties, or combinations thereof of the polymer resulting from the active synthesis conditions. Based on the monitoring, the one or more reactor control systems can thereby control the subsequent introduction of chemical reactants, catalysts, or combinations thereof into the one or more flow reactors. Thus, the one or more reactor control systems can modify the reaction conditions in the one or more flow reactors so that the properties of the resulting polymer correlate with the polymer being synthesized. In various embodiments, one or more reactor control systems can employ one or more computer models to determine how reaction conditions can be varied.

[0013] In various embodiments, the chemicals described herein are available from Sigma-Aldrich and can be used as received unless otherwise specified. For example, MDI can be prepared by sublimation under reduced pressure at 120 degrees Celsius (°C), and the resulting white crystalline solid can be stored in a glove box filled with nitrogen gas (N). Macrodiols (e.g., polyethylene glycol ("PEG") with a molecular weight ("Mn") of 1500 grams per mole (g / mol) ("PEG1500"), PEG with a Mn of 2000 g / mol ("PEG2000"), and polycaprolactone diol ("PCL") with a Mn of 2000 g / mol ("PCL2000")) can be dried three times by azeotropic vacuum distillation with anhydrous toluene and stored in an N-filled glove box. When preparing HDO, it can first be stored under vacuum at 40°C overnight to remove traces of water, and then stored in an N-filled glove box. 1,8-Octanediol can be sublimed under reduced pressure at 65-70°C. 2-Hydroxyethyl methacrylate ("HEMA") can be used without further purification. ε-Caprolactone (ε-CL) can be distilled under reduced pressure and stored in an N2-filled glove box with activated molecular sieves. DBU can be distilled under reduced pressure and stored in an N2-filled glove box. DBTDL, 1,5,7-triazabicyclo[4.4.0]dec-5-ene ("TBD"), yttrium(III) isopropoxide ("YIPO"), and azobisisobutyronitrile ("AIBN") can be used without further purification. Anhydrous tetrahydrofuran (THF) can be stored in an N2-filled glove box with activated molecular sieves.

[0014] As described herein 1 H nuclear magnetic resonance (" 1 H NMR data were collected at 400 megahertz (MHz) on a Bruker Avance 400 Spectrometer at 20°C, and chemical shifts are reported in ppm. Spectra were referenced to the signal of residual undeuterated species of the solvent used: chloroform-d (CDCl3: δ( 1H) = 7.26 ppm), dimethyl sulfoxide-d6 ((CD3)2SO:δ( 1 Attenuated total reflectance infrared spectroscopy ("ATR-FTIR") data presented herein was obtained using a Nicolet iS 5 FTIR Spectrometer at 2 cm -1 Interferograms were measured at a resolution of 100 kHz, and a total of 12 to 64 interferograms were averaged. In-line FTIR spectra were recorded using a Golden Gate Micro-Flow Cell Anvil connected to the spectrometer. The molecular weight characteristics described herein were analyzed by gel permeation chromatography ("GPC") using Agilent equipment. Measurements were performed using THF as the eluent at 25°C and a flow rate of 0.75 milliliters per minute (mL / min). Measurement results were analyzed following calibration with polystyrene standards. Chromatographs of polyurethane products were recorded only for monomer conversions of 90% or greater. Additionally, in various embodiments described herein, differential scanning calorimetry ("DSC") was performed on a DSC Q2000 or DSC 8500. Samples were sealed in aluminum pans and measured under a N2 atmosphere at a heating rate of 20°C / min or 5°C / min over a temperature range of -70°C to 150°C or -75°C to 110°C.

[0015] FIG. 1 illustrates an exemplary, non-limiting polymerization scheme 100 that can facilitate the synthesis of one or more polyurethanes 102 in one or more flow reactors 104 according to one or more embodiments described herein. Repeated descriptions of similar elements employed in other embodiments described herein are omitted for brevity. The one or more flow reactors 104 can include, for example, one or more inlets 106, channels 108, reactor loops 110, outlets 112, or combinations thereof. The one or more channels 108 can extend from the one or more inlets 106 to the one or more outlets 112. The one or more channels 108 (e.g., microfluidic channels) can include, for example, tubing (e.g., microfluidic tubing), pipes, joiners (e.g., T-mixers), or combinations thereof. Additionally, the one or more channels 108 can be directed to one or more reactor loops 110 at one or more stages between the one or more inlets 106 or outlets 112, or combinations thereof. The reactor loop(s) 110 can affect the length of the flow reactor(s) 104, thereby affecting the residence time of the chemical reaction(s) within the flow reactor(s) 104. For example, the length of the flow reactor(s) 104 (including the flow channels 108 or reactor loop(s) 110, or a combination thereof) can range, for example, from 1 centimeter (cm) to 1000 cm (e.g., 105 cm). Accordingly, the flow rate of the chemical reactants streaming through the flow reactor(s) 104 can range, for example, from 1 μL / min to 100 mL / s (e.g., 0.165 milliliters / min (mL / min)). Additionally, the residence time of the chemical reactants within the flow reactor(s) 104 can range, for example, from 0.1 seconds to 1 hour (e.g., 5 minutes). Those skilled in the art will recognize that the number of loops or loop dimensions, including the reactor loop(s) 110, or a combination thereof, can vary depending on the desired flow rate, residence time, turbulence, or a combination thereof.1 as being characterized by a circular configuration, the architecture of reactor loop 110 is not so limited. For example, one or more reactor loops 110 may be characterized by an elliptical, polygonal, or combination thereof configuration.

[0016] As shown in FIG. 1 , various chemical reactants can be introduced into the flow reactor 104 through respective inlets 106. In various embodiments, the first chemical reactant can be a mixture of a low molecular weight diol 114 and a macrodiol 116 introduced into the flow reactor 104 through a first inlet 106a. For example, the low molecular weight diol 114 can have a molecular weight of 44 g / mol to 1000 g / mol, inclusive. The macrodiol 116 can have a molecular weight of 500 g / mol to 5000 grams / mole (kg / mol), inclusive. In various embodiments, "R2" can be, for example, an alkyl chain containing 1 to 100 carbon atoms, inclusive. For example, "R2" can be characterized by the following chemical structure:

[0017] [ka]

[0018] In various examples, HDO can be employed as the low molecular weight diol 114 according to the following chemical structure:

[0019] [ka]

[0020] Additionally, "R3" can be characterized by at least one of the following chemical structures:

[0021] [ka]

[0022] Here, "n" can be, for example, an integer between 1 and 1000, "r" can be, for example, an integer between 1 and 1000, and / or "s" can be, for example, an integer between 1 and 500. Additionally, "A" can represent a single element such as oxygen, sulfur, selenium, or a combination thereof; an alkyl chain (e.g., containing between 1 and 1000 carbon atoms); a substituted nitrogen, silicon, phosphorus, boron atom, or a combination thereof; or a combination thereof. In one or more embodiments, PEG can be employed as macrodiol 116 according to the following chemical structure:

[0023] [ka]

[0024] In one or more embodiments, PCL may be employed as the macrodiol 116 according to the following chemical structure:

[0025] [ka]

[0026] In one or more embodiments, an example of macrodiol 116 can be characterized by the following chemical structure (1):

[0027] [ka]

[0028] In various embodiments, the low molecular weight diol 114 and the macrodiol 116 can be premixed before entering the flow reactor 104 (e.g., as shown in FIG. 1). The mixture can include, for example, a ratio of low molecular weight diol 114 to macrodiol 116 of 0:100 or more and 100:0 or less. Alternatively, a solution of the low molecular weight diol 114 can be introduced into the flow reactor 104 via the second inlet 106b. In various embodiments, the low molecular weight diol 114 and the macrodiol 116 can be introduced into the flow reactor 104 separately. For example, a solution of the macrodiol 116 can be introduced into the flow reactor 104 via the first inlet 106a, and a solution of the low molecular weight diol 114 can be introduced into the flow reactor 104 via the second inlet 106b.

[0029] Additionally, diisocyanate monomers 118 can be introduced into the flow reactor 104 via a third inlet 106c. Exemplary types of diisocyanate monomers 118 can include, but are not limited to, MDI, toluene diisocyanate ("TDI"), hexamethylene diisocyanate ("HDI"), isophorone diisocyanate ("IPDI"), or combinations thereof. 1」 can be a functional group derived from the diisocyanate monomer 118. For example, if the diisocyanate monomer 118 is MDI, then "R 1 " can be characterized by the following chemical structure:

[0030] [ka]

[0031] Additionally, catalyst 120 can be introduced into flow reactor 104 via fourth inlet 106d. In various embodiments, catalyst 120 can be an organic catalyst, an organometallic catalyst, or a combination thereof. Exemplary catalysts 120 can include, but are not limited to, DBU, DBTDL, TBD, YIPO, 1,4-diazabicyclo[2.2.2]octane ("DABCO"), bismuth octanoate, or a combination thereof.

[0032] Once introduced into the flow reactor 104, the chemical reactants (e.g., small molecule diol 114, macrodiol 116, diisocyanate monomer 118, catalyst 120, or combinations thereof) can react in one or more flow paths 108, reactor loop 110, or combinations thereof to synthesize one or more polyurethanes 102. In various embodiments, the reaction time for polyurethane 102 synthesis can be expressed as the residence time (“τ”), which is the time required for each fraction of the reaction mixture to pass through the flow reactor 104. The residence time can be determined by the dimensions of the flow reactor 104 and the applied flow rate, and can be calculated according to Equations 1-3 below.

[0033]

number

[0034] Here, "V R " is cubic centimeter (cm 3 ) and reactor volume in units of "Q R " is the volumetric flow rate (cm ) in the flow reactor 104 3 min -1 ) and "d R " is the inner diameter (cm) of one or more channels 108, and "l R " may be the length (in cm) of one or more of the channels 108 and reactor loop 110.

[0035] Parameters for the polyurethane 102 polymerization reaction in one or more flow reactors 104 can include, but are not limited to, reaction kinetics, residence time, size and volume of the flow reactor 104, viscosity of the starting solution and reaction mixture, mixing efficiency, solubility of potential by-products, and fluid properties that may change as the reaction progresses.

[0036] The retention time can be extended by decreasing the flow rate at which the chemical reactants (e.g., low molecular weight diol 114, macrodiol 116, diisocyanate monomer 118, catalyst 120, or a combination thereof) are introduced into the flow reactor 104, or by increasing the length, inner tubing diameter, or a combination thereof of either or both of the flow channel 108 and reactor loop 110, or by increasing the volume of the flow reactor 104. Also, if the reactant conversion rate of the polymerization reaction is higher than desired, a higher flow rate, a smaller flow reactor 104 volume, or a combination thereof can be employed.

[0037] The flow patterns of chemical reactants (e.g., low molecular weight diol 114, macrodiol 116, diisocyanate monomer 118, catalyst 120, or combinations thereof) within the flow reactor 104 can be classified as laminar and turbulent, or predicted by the Reynolds number ("Re"), or both. At low Re values ​​(e.g., less than 2000), the flow field of the chemical solution can be laminar, and mixing of the chemical reactants can be dominated by radial diffusion. For fast reactions, high Re values ​​above 5000 can be targeted to ensure turbulent flow that leads to fast, efficient mixing of the chemical reactants. With regard to reaction kinetics, the concentration of the monomers can also be varied within their solubility range to adjust the reaction rate.

[0038] As the chemical reactants react in the flow reactor 104, the polyurethane 102 may precipitate in one or more of the flow channels 108. In various embodiments, THF may be introduced into the flow reactor 104 via the fifth inlet 106e at a point downstream of one or more of the reactor loops 110. The THF may redissolve the precipitated product, thereby preventing clogging of one or more of the flow channels 108. In one or more embodiments, the synthesized polyurethane 102 may exit the flow reactor 104 via one or more outlets 112. For example, a stream of residual chemical reactants, polyurethane 102, or a combination thereof may flow out of one or more outlets 112 and into a collection vessel (not shown). In various embodiments, the collection vessel may be pre-loaded with a quenching solution, such as petroleum ether. The quenching solution may serve to quench the polymerization reaction of the polyurethane 102, one or more side reactions, or a combination thereof. Additionally, in one or more embodiments, the one or more polyurethanes 102 can be precipitated in methanol, or isolated by vacuum filtration, or both.

[0039] As shown in FIG. 1 , the one or more polyurethanes 102 can include hard segments, soft segments, or a combination thereof. The hard segments can be derived from diisocyanate monomers 118 and low molecular weight diols 114. Further, the number of hard segments in the one or more polyurethanes 102 can be defined by “x,” where “x” can be, for example, a number (e.g., a decimal number) between 0 and 1000. The soft segments can be derived from diisocyanate monomers 118 and macrodiols 116. Further, the number of soft segments in the one or more polyurethanes 102 can be defined by “y,” where “y” can be, for example, a number (e.g., a decimal number) between 0 and 1000. In various embodiments, the distribution of the one or more hard and soft segments can be random along the polymer backbone of the one or more polyurethanes 102 (e.g., as indicated by “ran” in FIG. 1 ).

[0040] FIG. 2 shows an exemplary, non-limiting polymerization scheme 100a that may illustrate features of polymerization scheme 100 by employing HDO as low molecular weight diol 114, PEG (e.g., PEG1500) as macrodiol 116, MDI as diisocyanate monomer 118, and DBTDL as catalyst 120, according to various embodiments described herein. Repeated descriptions of similar elements employed in other embodiments described herein are omitted for brevity. The chemical structure of polyurethane 102 resulting from the exemplary chemical reactants is shown in FIG. 2. Those skilled in the art will recognize that the chemical reactants illustrated in FIG. 2 are shown to illustrate features of polymerization scheme 100, and that alternative chemical reactants (e.g., alternative low molecular weight diol 114, macrodiol 116, diisocyanate monomer 118, catalyst 120, or combinations thereof) may be employed according to various embodiments described herein (e.g., at least as described in FIG. 1).

[0041] The use of a flow reactor 104 to carry out the polymerization scheme 100 can allow for on-demand changes in synthesis variables. For example, the flow reactor 104 setup shown in Figure 2 allows for the diol ratio HDO:PEG to be changed on-demand from 50:50 to 100:0, thereby facilitating the generation of a library of polyurethanes 102 each having varying amounts of hard and soft segments, or facilitating the screening of relationships between compositional properties and material properties, or both.

[0042] To demonstrate the effectiveness of carrying out the polymerization scheme 100 in the flow reactor 104, the hard segment weight fraction (w HSFive types of linear polyurethanes 102 with different densities (%) were prepared in a single experiment according to the characteristics shown in FIG. 2, and the reactants were collected as soon as the conversion rate stabilized at 90% or more. The experimental results are shown in Table 1 below. For example, "FlowPU1" can be a first example polyurethane 102 having a first amount of hard segments, "FlowPU2" can be a second example polyurethane 102 having a second amount of hard segments, "FlowPU3" can be a third example polyurethane 102 having a third amount of hard segments, "FlowPU4" can be a fourth example polyurethane 102 having a fourth amount of hard segments, and "FlowPU5" can be a fifth example polyurethane 102 having a fifth amount of hard segments. The formation of polyurethanes 102 is 1 HNMR, FTIR, and the mole fraction χ of HDO in all diols HDO W calculated from HS Confirmed by χ HDO The theoretical values ​​(e.g., indicated by the "th" subscript) and experimental values ​​(e.g., indicated by the "exp" subscript) are in agreement with an average deviation of only -3.2 ± 1.1%. GPC analysis results showed high weight-average molecular weights Mw in the range of 30.8 to 39.6 kilodaltons (kids) and low polydispersities of 1.3 to 1.4. HS Increasing σ, thereby increasing the density of urethane groups along the polymer backbone, can shift the glass transition temperature Tg of polyurethane 102 to higher values, which may indicate a decrease in chain mobility (e.g., making polyurethane 102 stiffer).

[0043] [Table 1]

[0044] In various embodiments, the conversion of the reactants in the polymerization reaction can be determined by tracking the disappearance of the hydroxy proton of the diol and the subsequent appearance of a methylene group adjacent to the urethane bond. The conversion of the reactants was calculated using Equation 4. In Equation 4, "A Pol,-CH2-OCONH-” is the area of ​​the methylene groups of the polymer adjacent to the urethane moiety (4.16 ppm for PEG, 4.03 ppm for PCL and HDO), and “A Mon,-OH " is the area of ​​the alcohol protons of the diol (4.59 ppm for PEG, 4.36 ppm for PCL and HDO).

[0045]

number

[0046] The conversion of each diol reactant can be calculated separately and expressed as the average of both according to their respective presence in the polyurethane 102.

[0047] The mole fraction (χ ) of low molecular weight diol 114 (e.g., HDO) in the total diols incorporated into polyurethane 102 HDO ) is the purified product 1 From the H NMR spectrum, the χ can be determined by integrating the areas associated with the peaks of the methylene groups attached to the urethane bonds of both diols. For example, when the macrodiol 116 is PEG and the low molecular weight diol 114 is HDO, the χ HDO can be determined according to Equation 5.

[0048]

number

[0049] Here, "A HDO,-CH2-OCONH- " may have a center at 4.03 ppm, and "A PEG,-CH2-OCONH- " can be present at 4.16 ppm.

[0050] Polyurethane 102 incorporating PCL as macrodiol 116 and HDO as low molecular weight diol 114 1 In the H NMR spectrum, the area from 4.10 to 3.90 ppm is the overlap of signals corresponding to the methylene protons of PCL and HDO adjacent to the urethane group, respectively. PCL+HDO,-CH2-OCONH- ". Thus, Equation 6 can be expressed as the experimentally determined degree of polymerization, DPNMR , and the area of ​​the signal at 2.27 ppm corresponding to the PCL methylene proton adjacent to the PCL carbonyl carbon atom, “A PCL,-CH2-CO- " can be adopted taking into consideration the above.

[0051]

number

[0052] The HDO percentage can further be used to determine the percentage of hard segments in the polyurethane 102.

[0053] The low molecular weight diol 114 and the macrodiol 116 can have different thermal properties. The low molecular weight diol 114 can form hard segments in the polymer backbone of the polyurethane 102, where the hard segments have a melting temperature above ambient conditions. The macrodiol 116 can form soft segments in the polymer backbone of the polyurethane 102, where the soft segments have a glass transition temperature below ambient conditions. Segmented polyurethanes can be synthesized using diols with significantly different thermal properties. For example, the hard segments of the polyurethane 102 can be formed from MDI and HDO, with corresponding hard segment weight fractions "w HS " can be calculated according to Equation 7.

[0054]

number

[0055] Here, "M MDI " can be the molecular weight of MDI, and "M HDO " can be the molecular weight of HDO, and "M macrodiol " may be the molecular weight of macrodiol 116, and "χ HDO " is the mole fraction of HDO in polyurethane 102.

[0056] In various embodiments, polyurethanes 102 included in Table 1 can be prepared using one or more flow reactors 104 as follows: In an N2-filled glovebox, a 0.48 M solution of PEG1500:HDO (50:50) in anhydrous THF can be prepared by dissolving 4920 mg (3.20 mmol, 0.50 eq) of PEG1500 and 378 mg (3.20 mmol, 0.50 eq) of HDO to a total volume of 13.3 mL; a 0.48 M solution of HDO only can be prepared by dissolving 378 mg (3.20 mmol, 0.50 eq) of HDO in anhydrous THF to a total volume of 6.6 mL; a 1.92 M solution of MDI can be prepared by dissolving 1602 mg (6.40 mmol, 1 eq) of MDI in anhydrous THF to a total volume of 3.3 mL. A 19.2 mM DBTDL solution contains 4.0 mg (6.4 x 10 -3 mmol, 1x10 -3 The polyurethanes were prepared by dissolving 102 equivalents of DBTDL in 3.2 mL of anhydrous THF. The residence time of one or more flow reactors 104 was set to 20 minutes, corresponding to a total flow rate of 36 μL / min. The molar feed ratio of macrodiol PEG1500 and HDO was periodically varied by changing the flow rates of the PEG1500:HDO (50:50) mixture and the pure HDO solution. Table 2 shows the reaction conditions for the synthesis of the polyurethanes 102 included in Table 1.

[0057] [Table 2]

[0058] 2 , the one or more flow reactors 104 may be further coupled to one or more reactor control systems 200. In various embodiments, the one or more reactor control systems 200 may comprise one or more PID controllers 202, measurement devices 204, networks 206, computing devices 208, or combinations thereof. In one or more embodiments, the one or more PID controllers 202 may be coupled to one or more inlets 106. For example, a first PID controller 202 may be coupled to the first inlet 106a, a second PID controller 202 may be coupled to the second inlet 106b, a third PID controller 202 may be coupled to the third inlet 106c, a fourth PID controller 202 may be coupled to the fourth inlet 106d, a fifth PID controller 202 may be coupled to the fifth inlet 106e, or combinations thereof. One or more PID controllers 202 may be coupled to one or more inlets 106 via a direct electrical connection, a wireless connection, or a combination thereof.

[0059] In various embodiments, one or more PID controllers 202 can be employed by the reactor control system 200 to control one or more inlets 106. For example, the one or more PID controllers 202 can control when one or more inlets 106 are in an open or closed state. In another example, the one or more PID controllers 202 can control the duration for which a given inlet 106 is in an open or closed state. In a further example, the one or more PID controllers 202 can be coupled to one or more pumps (not shown) for the inlets 106, thereby controlling the pressure at which chemical reactants are introduced into the flow reactor 104 and varying the flow rate of one or more of the chemical reactants.

[0060] 2, the one or more PID controllers 202 can be further coupled to one or more computing devices 208. The one or more PID controllers 202 can be coupled to the one or more computing devices 208 directly or via one or more networks 206 (e.g., via a direct electrical connection, via a wireless connection, or via a combination thereof). The one or more computing devices 208 can also be coupled to one or more measurement devices 204 directly or via one or more networks 206 (e.g., via a direct electrical connection, via a wireless connection, or via a combination thereof).

[0061] One or more measurement devices 204 can be positioned adjacent to one or more flow paths 108 of the flow reactor 104. For example, one or more measurement devices 204 can be positioned downstream of one or more reactor loops 110. In various embodiments, the one or more measurement devices 204 can measure and / or monitor chemical properties, physical properties, or a combination thereof, of a chemical stream within a portion of one or more flow paths 108. For example, the one or more measurement devices 204 can measure and / or monitor chemical properties, physical properties, or a combination thereof, of the synthesized polyurethane 102 within one or more flow paths 108. For example, the one or more measurement devices 204 can measure and / or monitor properties of the synthesized polyurethane 102 before the polyurethane 102 exits one or more flow reactors 104. In one or more embodiments, the one or more measurement devices 204 can be in fluid communication with one or more flow paths 108. In one or more embodiments, the one or more measurement devices 204 can be external to fluid communication with one or more flow paths 108 and can measure and / or monitor properties of the chemical stream through the walls of the flow paths 108 (e.g., at least a portion of one or more flow paths 108 can be transparent, and the one or more measurement devices 204 can optically measure and / or monitor the chemical stream). Exemplary types of data that can be measured and / or monitored by the one or more measurement devices 204 include, but are not limited to, FTIR spectra, NMR spectra, ultraviolet-visible (“UV-Vis”) spectra, near-infrared (“NIR”) spectra, or combinations thereof. Exemplary types of measurement devices 204 include, but are not limited to, a Nicolet iS5 FTIR spectrometer in ATR mode with a flow cell, a Nanalysis NMReady-60pro with a flow cell kit, an Agilent Cary 5000 UV-Vis-NIR with a flow-through cuvette, or combinations thereof. For example, the one or more measuring devices 204 may be -1The ATR-FTIR instrument may be an ATR-FTIR instrument with a flow cell placed in-line with one or more portions of the flow channels 108 to monitor the reactant conversion rate of the polymerization reaction in the flow reactor 104 in real time by tracking the characteristic NCO stretching band of the monomer.

[0062] In various embodiments, the one or more computing devices 208 can control the one or more PID controllers 202 based on data collected or generated by the one or more measurement devices 204, or both, to modify synthesis conditions within the one or more flow reactors 104. In one or more embodiments, the one or more computing devices 208 can generate one or more computer models to determine how modifying the operation of one or more inlets 106 can affect the chemical or physical properties of the polyurethane 102 synthesized in the flow reactor 104 and observed by the one or more measurement devices 204. For example, the one or more computing devices 208 can identify, based on data collected or generated by the one or more measurement devices 204, or both, when the polyurethane 102 being synthesized in the flow reactor 104 has chemical or physical properties, or both, outside of a target property profile. For example, the one or more computing devices 208 can identify whether the polyurethane 102 polymerization reaction is achieving a desired reactant conversion rate. Additionally, the one or more computing devices 208 can determine, based on the one or more computer models, one or more changes to the amounts or flow rates of one or more chemical reactants, or both, that can result in the properties of the subsequently synthesized polyurethane 102 conforming to the target property profile, and the one or more computing devices 208 can control the one or more PID controllers 202 to implement the one or more changes.

[0063] To demonstrate the effectiveness of catalyst 120 in polymerization scheme 100, three different catalysts 120 were investigated in the polymerization of PEG1500:HDO and MDI using flow reactor 104. For each polymerization, monomer solutions were prepared as follows: In an N2-filled glovebox, a 0.48 molar (M) PEG1500:HDO (40:60) solution was prepared by dissolving 2243 milligrams (mg) (1.46 millimoles (mmol), 0.40 equivalents) of PEG1500 and 259 mg (2.19 mmol, 0.60 equivalents) of HDO in anhydrous THF to a total volume of 7.6 mL. A 1.92 M MDI solution was prepared by dissolving 913 mg (3.65 mmol, 1.00 equivalents) of MDI in anhydrous THF to a total volume of 1.9 mL.

[0064] The first reaction was catalyzed by 1.0 mol% DBTDL, where a 19.2 mM DBTDL solution was used to prepare 23 mg (3.65 x 10 -2 The second reaction was catalyzed by 0.1 mol% DBTDL, where a 1.92 mM DBTDL solution was prepared by dissolving 2.0 mg (3.65 x 10 mmol) of DBTDL in anhydrous THF to a total volume of 1.9 mL. -3 mmol, 1x10 -3 A third reaction was catalyzed by 5 mol% DBU, where a 0.096 M DBU solution was prepared by dissolving 28 mg (0.182 mmol, 0.05 eq) of DBU in 1.9 mL of anhydrous THF. The residence time of the reaction can be varied by changing the flow rates associated with each inlet 106. For example, to keep the stoichiometry constant, a 4:1:1 flow ratio of PEG1500 / HDO:MDI:catalyst solution can be maintained. For example, Table 3 below shows the residence times, flow rates, or combinations thereof associated with three different catalyst 120 conditions.

[0065] [Table 3]

[0066] The reaction was carried out with a 1.5x hold time before collecting the synthesized polyurethane 102 to allow steady state in the flow reactor 104. After the synthesis reaction, the flow reactor 104 can be flushed with anhydrous THF. To evaluate the three reactions above (e.g., involving three different catalyst 120 conditions), the polyurethane 102 product was precipitated in petroleum ether, dried under reduced pressure, and then purified. 1 The crude sample can be redissolved in DMSO-d6 for HNMR analysis. The crude sample was redissolved in THF and precipitated twice in methanol (MeOH). When DBU was used as the catalyst 120, MeOH containing 4 vol% 2,2,2-trifluoroacetic acid (TFA) was used for precipitation. The resulting white solid was dried under reduced pressure and 1 It can be analyzed by HNMR, FTIR and GPC.

[0067] 3 shows an exemplary, non-limiting graph illustrating the reaction rates over time associated with polymerization scheme 100a for three different exemplary catalyst 120 conditions (e.g., 1.0 mol% DBTDL, 0.1 mol% DBTDL, and 5.0 mol% DBU), according to various embodiments described herein. In graph 300, line 302 represents the reaction rates of reactants over time associated with polymerization scheme 100a in which 0.1 mol% DBTDL is employed as catalyst 120. In graph 304, line 306 represents the reaction rates of reactants over time associated with polymerization scheme 100a in which 5.0 mol% DBTDL is employed as catalyst 120, and line 308 represents the reaction rates of reactants over time associated with polymerization scheme 100a in which 1.0 mol% DBU is employed as catalyst 120 (e.g., rather than DBTDL).

[0068] In various embodiments, the use of DBTDL as catalyst 120 can achieve complete conversion of the chemical reactants to polyurethane 102 within about 2 minutes at a catalyst loading of 1 mol %. In one or more embodiments, DBTDL can be effectively replaced by DBU, which may also be easier to remove during purification with the aid of acid.

[0069] In various embodiments, an ATR-FTIR instrument can be employed as one or more of the measurement devices 204. The ATR-FTIR instrument can be calibrated according to the following description. In an N2-filled glovebox, a 0.32 M solution of MDI can be prepared by dissolving 80.1 mg (0.32 mmol) of MDI in anhydrous THF for a total volume of 1 mL. 2 mL of anhydrous THF can also be prepared. The MDI solution and anhydrous THF can be introduced into the flow reactor 104 via their respective inlets 106. The flow rates of the MDI and anhydrous THF solutions can be varied every 3 minutes while maintaining a total flow rate of 36 μL / min, thereby simulating the consumption of isocyanate groups in the diisocyanate monomer 118 during the polymerization scheme 100. Table 4, shown below, shows the calculated flow rates and MDI concentrations associated with a calibration example.

[0070] [Table 4]

[0071] Also, during an exemplary calibration, an FTIR spectrum may be recorded every 20 seconds. Figure 4 shows exemplary, non-limiting graphs of FTIR spectra that may be recorded during an exemplary calibration in accordance with various embodiments described herein. Graph 402 shows the peak at 2270 cm with decreasing concentration. -1 Graph 402 shows a portion of an FTIR spectrum illustrating the decrease in absorbance of the characteristic NCO band at 2270 cm. As is evident from graph 402, a high flow rate with a short residence time can be associated with a synthesis reaction having a low reactant conversion rate, while a low flow rate with a long residence time can be associated with a synthesis reaction having a high reactant conversion rate. Graph 404 shows the decrease in absorbance of the characteristic NCO band at 2270 cm. -1 1 shows a plot showing the dependence of absorbance on MDI concentration at 1000 nm.

[0072] The correlation is the concentration of MDI, c MDI " and 2270cm -1 Absorbance at 2270 "). Linear regression can bring Equation 8 back to describe the dependency numerically.

[0073]

number

[0074] Equation 8 can be employed by one or more computing devices 208 to calculate the reaction rates of reactants during a synthesis reaction in one or more flow reactors 104.

[0075] In various embodiments, the reactant conversion rates can be determined autonomously by one or more computing devices 208 according to a predefined schedule (e.g., the reactant conversion rates can be determined at set time intervals, such as every 20 seconds). Table 5, shown below, provides reactant conversion data for the exemplary polyurethane 102 polymerization reaction characterized by Tables 1-2. As soon as the reactant conversion rate reached a plateau greater than 90%, the product fraction was collected, precipitated directly into petroleum ether, filtered, redissolved in THF, and precipitated into MeOH. After two additional rounds of purification by precipitation, the solvent was removed under reduced pressure, and the product was analyzed by FTIR. 1 The properties were evaluated using HNMR, GPC, TGA and DSC.

[0076] [Table 5]

[0077] 5 illustrates an exemplary, non-limiting control scheme 500 that can be employed by the reactor control system 200 to control one or more flow reactors 104 in accordance with one or more embodiments described herein. Repeated descriptions of similar elements employed in other embodiments described herein are omitted for brevity. In various embodiments, one or more PID controllers 202 can set the total flow rate ("Q") of one or more inlets 106. Additionally, the length of the flow reactor 104 (e.g., including the length of one or more flow channels 108 and the reactor loop 110) can be represented as "L," and the cross-sectional area can be represented as "A." The reaction kinetic constant can be represented as "k," the flow rate through the pump as "Q(t)," and the stoichiometric equivalent relative to the reference concentration (0.32 M) as "A."

[0078] According to various embodiments, the one or more measurement devices 204 can be one or more ATR-FTIR sensors disposed downstream of one or more reactor loops 110, and the sensor data 502 can relate to a conversion rate value of one or more chemical reactants. Additionally, conversion setpoint data 504 can be provided to one or more computing devices 208 (e.g., via one or more input devices 506). In various embodiments, the conversion setpoint data 504 can characterize a target point in the conversion rate of a reactant. One or more entities employing the flow reactor 104 or the reactor control system 200, or both, can define the conversion setpoint data 504 via one or more input devices 106, such as one or more computing devices. -1Considering the vibrational characteristics of a diisocyanate monomer 118 (e.g., MDI) having an asymmetric NCO stretch centered at , one or more computing devices 208 can calculate reaction rates for controlling one or more flow reactors 104 to carry out the polymerization scheme 100. For example, one or more computing devices 208 can input reaction rates of reactants of a synthesis reaction occurring in one or more flow reactors 104, measured by one or more measurement devices 204, to calculate flow rates for one or more inlets 106. The measured reaction rates of reactants are expected to be higher as the flow rates decrease and lower as the flow rates increase.

[0079] In various embodiments, a variable time delay may be experienced between process changes (e.g., between flow rate changes, or between data collection by one or more measurement devices 204 at the end of the flow reactor 104, or both). The time delay may range, for example, from several milliseconds to up to an hour (e.g., 5 minutes). In one or more embodiments, a Smith Predictor algorithm may be employed by one or more computing devices 208 to mitigate degradation of controller performance due to time delays. For example, one or more computing devices 208 may generate a computer process model to predict the future effects of changing one or more flow rates of chemical reactants. The one or more computing devices 208 may then employ a Smith Predictor algorithm within the computer process model to control one or more PID controllers 202. By employing this model prediction, delay times may be mitigated, and the PID controllers 202 may receive immediate or near-immediate feedback on process changes to the settings of the flow reactor 104. In one or more embodiments, the one or more computing devices 208 can further improve the accuracy of the PID controllers 202, and therefore the settings of the flow reactor 104, by controlling the one or more PID controllers 202 based on future predictions in addition to current predictions of the computer process model compared to data collected by the one or more measurement devices 204. In other words, the one or more computing devices 208 can analyze the accuracy of past predictions by comparing the predictions to chemical or physical properties, or both, observed by the one or more measurement devices 204. Thus, the one or more computing devices 208 can control the one or more PID controllers 202 based on signals that can mitigate any discrepancies between the process model and the actual measurements made by the one or more measurement devices 204, as well as lag time issues.

[0080] In one or more embodiments, the process model employed by the one or more computing devices 208 may be a second-order reaction kinetics scheme utilizing rate constant values ​​that give a 90% reaction rate in 5 minutes for an initial MDI concentration of 0.32 M. A plug flow approximation was employed to calculate the reaction / residence time in one or more measurement devices 204. The expected inverse relationship between reaction rate in the measurement device 204 and flow rate is described by Equation 9, which depends on the expected steady-state or future reaction rate for a given flow rate.

[0081]

number

[0082] Similarly, by numerically solving Equation 9, one or more computing devices 208 can calculate the currently expected reaction rates at one or more measurement devices 204 according to Equation 10, and thus the discrepancy between the process model and the measurements can be calculated.

[0083]

number

[0084] 6 illustrates another exemplary, non-limiting control scheme 600 that may be employed by the reactor control system 200 to control one or more flow reactors 104 in accordance with one or more embodiments described herein. Repeated descriptions of similar elements employed in other embodiments described herein are omitted for brevity. As shown in FIG. 6, "({k}, {[A]})" may be the rate law of a chemical process as a function of the chemical species concentration "{[A]}" and the reaction rate constant "{k}." Furthermore, "conversion" may be used to denote the rate law of a chemical process as a function of the chemical species concentration "{[A]}" and the reaction rate constant "{k}." steady-state ” is the flow rate “Q” based on the kinetic model fitting parameter {k} pump ” and the steady-state conversion rate of τ rt " may be the residence time in the flow reactor 104, and "conversionFTIR " may be a conversion value determined by one or more measurement devices 204 (e.g., ATR-FTIR sensors). The deviation of the predicted conversion rate at steady state from the "SetPoint" may be represented by "Error(e)" and provided as an input to the PID controller 202.

[0085] According to various embodiments, the one or more measurement devices 204 can be one or more ATR-FTIR sensors disposed downstream of one or more reactor loops 110, and the sensor data 502 can relate to reactant reaction rates of one or more chemical reactants. For example, the reactant reaction rates can be determined by the one or more measurement devices 204 by tracking infrared ("IR") isocyanate peaks in one or more FTIR analyses. According to one or more embodiments described herein, the one or more FTIR analyses can track the IR isocyanate peaks versus diisocyanate monomer 118 concentration (e.g., MDI concentration (c MDI )) can be based on a calibration of. For example, a linear regression model can be employed to plot the diisocyanate monomer 118 concentration as a function of time (“t”), e.g., c MDI The time ("c MDI (t)") can be determined as a function of the MDI stock solution concentration. MDI Using (t=0), the reactant conversion rate calculated on demand at the end of the flow reactor 104 can be calculated according to Equation 11 below:

[0086]

number

[0087] 7 illustrates an exemplary, non-limiting polymerization scheme 100 in which one or more macrodiols 116 may be further synthesized in one or more flow reactors 104 according to one or more embodiments described herein. Repetitive descriptions of similar elements employed in other embodiments described herein are omitted for brevity. As shown in FIG. 7, a first inlet 106a can introduce a solution of one or more macrodiols 116 into the flow reactor 104 for further mixing with one or more low molecular weight diols 114, diisocyanate monomers 118, catalysts 120, or combinations thereof.

[0088] In various embodiments, one or more macrodiols 116 can be synthesized in one or more additional flow reactors 104 connected to the first inlet 106a. For example, one or more macrodiols 116 can be synthesized from one or more monomers 702 introduced into the flow reactor 104 via the sixth inlet 106f and an initiator / catalyst solution 704 of one or more initiators and urea catalysts introduced into the flow reactor 104 via the seventh inlet 106g. The one or more monomers 702 can be, for example, cyclic monomers (e.g., cyclic ester monomers). Exemplary types of monomers 702 can include, but are not limited to, ε-caprolactone, γ-valerolactone, γ-butyrolactone, lactide, or combinations thereof. The one or more initiators can be, for example, diol monomers (e.g., diol monomers containing alkyl chains). Exemplary types of initiators include, but are not limited to, 1,8-octanediol, 1,6-hexanediol, diethylene glycol, or combinations thereof. Examples of urea catalysts include, but are not limited to, 1,3-bis[3,5-bis(trifluoromethyl)phenyl]urea, 1-[3,5-bis(trifluoromethyl)phenyl]-3-[4-(trifluoromethyl)phenyl]urea, N-[3,5-bis(trifluoromethyl)-phenyl]-N'-phenylurea, N-[3,5-bis(trifluoromethyl)phenyl]-N'-cyclohexylurea, 1-phenyl-3-(3-(trifluoromethyl)phenyl)urea, 1,3-diphenylurea, 1-cyclohexyl-3-phenylurea, each thiourea, or combinations thereof.

[0089] In various embodiments, the initiator / catalyst solution 704 can further include a base compound capable of deprotonating one or more urea catalysts to form an anionic urea catalyst. In one or more embodiments, catalytic activity can increase as the acidity of the one or more urea catalysts decreases. Also, in one or more embodiments, the one or more urea catalysts are based on the monomers 702 to be polymerized. For example, the selection of a urea catalyst utilized in a target ring-opening polymerization ("ROP") can correspond to monomers 702 of different reactivity or stability, or a combination thereof. Thus, one or more polymerization conditions (e.g., reaction rate, molecular weight dispersity, or a combination thereof) can be adjusted by varying the identity, concentration, or a combination thereof of the urea catalyst without changing one or more parameters of the flow reactor 104. Furthermore, one or more monomers 702 can undergo one or more ROPs in the presence of the initiator / catalyst solution 704 to form one or more macrodiols 116.

[0090] Additionally, the flow reactor 104 facilitating the synthesis of macrodiols 116 can include an eighth inlet 106h. For example, a quenching solution 706 can be introduced into the flow reactor 104 to quench the polymerization reaction forming one or more macrodiols 116. The quenching solution 706 can include, for example, benzoic acid, hydrochloric acid, sulfuric acid, carbonic acid, formic acid, citric acid, trifluoroacetic acid, or a combination thereof.

[0091] While FIG. 7 illustrates two inlets 106 (e.g., a sixth inlet 106f, a seventh inlet 106g, or a combination thereof) employed to synthesize one or more macrodiols 116, the architecture of one or more flow reactors 104 is not so limited. For example, multiple different monomers 702 can be coupled to each inlet 106. The type of macrodiol 116 synthesized in one or more flow reactors 104 can thereby be varied by controlling the inlets 106 to introduce different monomers 702 into one or more flow reactors 104. Similarly, multiple different initiator / catalyst solutions 704 can be coupled to each inlet 106. For example, the different initiator / catalyst solutions 704 can include alternating combinations of various initiators or urea catalysts, or both, as described herein. The type of macrodiol 116 synthesized in one or more flow reactors 104 can thereby be varied by controlling the inlets 106 to introduce different initiator / catalyst solutions 704 into one or more flow reactors 104.

[0092] FIG. 8 illustrates an exemplary, non-limiting polymerization scheme 100 in which, according to one or more embodiments described herein, one or more macrodiols 116 can be PCL (e.g., PCL2800) synthesized via one or more flow reactors 104, one or more low molecular weight diols 114 can be HDO, the diisocyanate monomer 118 can be MDI, and the catalyst 120 can be DBTDL. Repetitive descriptions of similar elements employed in other embodiments described herein are omitted for brevity. As shown in FIG. 8 , in the exemplary embodiment, one or more macrodiols 116 can be PCL and can be synthesized in one or more reactor loops 110 connected to the first inlet 106a. For example, PCL can be synthesized in one or more flow reactors 104 according to the following polymerization scheme: In the polymerization scheme, “rt” represents room temperature.

[0093] [ka]

[0094] For example, the one or more initiators can be 1,8-octanediol, the one or more urea catalysts can be N'-phenyl-3-(trifluoromethyl)benzohydrazide, the one or more monomers 702 can be ε-caprolactone, and the one or more macrodiols 116 can be PCL2800 (e.g., PCL having a molecular weight of 2800 g / mol). In various embodiments, the one or more monomers 702, initiator / catalyst solution 704, or a combination thereof can be prepared as follows: In an N2-filled glovebox, a 2.1 M monomer 702 solution can be prepared by dissolving 12.00 g (105.13 mmol) of ε-caprolactone in anhydrous THF up to a total volume of 50 mL. This solution can be further passed through a 0.2 μm PTFE filter. To prepare initiator / catalyst solution 704, 0.60 g (4.10 mmol, 1.0 equiv.) of 1,8-octanediol and 3.45 g (12.32 mmol, 3.0 equiv.) of CF3PhUPh were dissolved in 20 mL of anhydrous THF and combined with a suspension of 0.33 g (8.21 mmol, 2.0 equiv.) of potassium hydride (KH) in 20 mL of anhydrous THF. Stirring of this mixture can be stopped 15 minutes after gas formation has ceased. This mixture can be further diluted to 54 mL with anhydrous THF and passed through a 0.2 μm PTFE filter. Quenching solution 706 can be prepared by dissolving 6.01 g (49.24 mmol, 12.0 equiv.) of benzoic acid in 40 mL of THF. Table 6 below lists the polymerization parameters for the synthesis of PCL2800, shown in Figure 8.

[0095] [Table 6]

[0096] In addition, the synthesis of PCL2800 described above had a reaction rate of 88%, a yield of 9.17 g of PCL2800, and GPC (THF, 25°C):M n = 4.11 kg / mol, M w= 5.36 kg / mol, D = 1.30, DP NMR =23.5, M n,NMR = 2824 g / mol, and / or 1 HNMR analysis: (400 MHz, DMSO-d6, δ) = 4.35 (2H), 3.98 (47H), 3.35 (4H), 2.27 (47H, d), 1.75-1.03 (157H) can be achieved.

[0097] 8, the reactor control system 200 can be scaled to further control the synthesis of one or more macrodiols 116 in one or more flow reactors 104. For example, one or more of the PID controllers 202 can control the operation of the sixth inlet 106f, the seventh inlet 106g, or a combination thereof, to vary the flow rates associated with one or more monomers 702, initiator / catalyst solution 704, or a combination thereof, to control the synthesis of one or more macrodiols 116. The reactor control system 200 can also include a second measurement device 204b positioned before the first inlet 106a, downstream of one or more reactor loops 110 employed to synthesize one or more macrodiols 116. The one or more second measurement devices 204b can collect sensor data related to chemical or physical properties, or both, of the macrodiols 116 to facilitate the one or more computing devices 208 in controlling the flow rates of the monomers 702, initiator / catalyst solution 704, or a combination thereof.

[0098] For example, the one or more second measurement devices 204b can be ATR-FTIR devices capable of measuring reactant reaction rates. Further, the one or more computing devices 208 can generate one or more computer process models based on the measured reactant reaction rates and one or more Smith Prediction algorithms according to one or more embodiments described herein.

[0099] 9 illustrates an exemplary, non-limiting polymerization scheme 100, which further includes one or more end-capping groups attached to the termini of the polymer backbones of one or more polyurethanes 102, according to one or more embodiments described herein. Repetitive descriptions of similar elements employed in other embodiments described herein are omitted for brevity. In various embodiments, chain growth of one or more polyurethanes 102 can be controlled via one or more end-capping groups disposed at the termini of the polymer backbones of the polyurethanes 102.

[0100] For example, one or more end capping groups can be derived from a monofunctional alcohol, such as HEMA. As shown in Figure 9, HEMA can be introduced into one or more flow reactors 104 via a ninth inlet 106i. For example, HEMA can be introduced into one or more flow reactors 104 at a molar fraction χ of 9.5%, while maintaining an equimolar ratio of isocyanate groups to hydroxyl groups. HEMA,th (For example, all hydroxy groups χ OH,HEMA The HEMA end-capped polyurethane 102 can be introduced into one or more flow reactors 104 at a concentration of 16 kDa or more (equivalent to 5% of the hydroxy groups in the polymer) to synthesize a HEMA end-capped polyurethane 102 (e.g., as shown in FIG. 9) having a predefined molecular weight range of 16 kDa to 29 kDa. Furthermore, in one or more embodiments, the HEMA end-capped polyurethane 102 can act as a macro-crosslinker in radical polymerization.

[0101] To illustrate one or more features of the polymerization scheme 100 shown in FIG. 9 , a target PCL macrodiol 116, PCL2800, was prepared from 1,8-octanediol (e.g., initiator in initiator / catalyst solution 704) and ε-CL (e.g., monomer 702) by flow-through ROP. Small-scale, large-scale, or combinations of these polyaddition reactions, catalyzed by 5 mol% DBU, demonstrated vigorous and reliable behavior at residence times between 210 and 300 seconds, resulting in monomer conversion rates averaging 98.5%. Furthermore, monitoring by one or more measurement devices 204 may enable the reactor control system 200 to optimize or control the flow rate and residence time associated with HEMA, or both. Table 7, below, presents experimental results related to the polymerization scheme shown in FIG. 9 . For example, "FlowPU6" can be the sixth example polyurethane 102 having one or more HEMA endcap groups, "FlowPU7" can be the seventh example polyurethane 102 having one or more HEMA endcap groups, "FlowPU8" can be the eighth example polyurethane 102 having one or more HEMA endcap groups, "FlowPU9" can be the ninth example polyurethane 102 having one or more HEMA endcap groups, "FlowPU10" can be the tenth example polyurethane 102 having one or more HEMA endcap groups, and "FlowPU11" can be the eleventh example polyurethane 102 having one or more HEMA endcap groups. The HDO mole fraction values ​​are in good agreement with the theoretical values, with an absolute mean difference of only -0.4±2.2%, and the total diol χ HEMA The molar amount of HEMA in the solution showed a low absolute deviation of -0.9±1.4% from the theoretical value of 9.5%.

[0102] [Table 7]

[0103] As shown in Table 7, the determined molecular weights were in agreement with the theoretical values ​​given the observed conversion rates. HDO and χ HEMAThe difference between theoretical and experimental values ​​for ρ can result in a small deviation of an average of 1.1 kDa (8.2%). In one or more embodiments, polyurethanes 102, FlowPU8-11, can be compounded with azobisisobutyronitrile ("AIBN"), cast into disks, and thermally crosslinked neat. Similarly, FlowPU9 can be compounded with butyl methacrylate in a 3:1 weight ratio in THF and thermally crosslinked with 5 wt% AIBN. The resulting gel is insoluble in THF.

[0104] In various embodiments, the theoretical mole fraction χ of HEMA in total diols HEMA,th can be calculated according to Equation 12. Furthermore, the molar fraction of HEMA hydroxyl groups in the total hydroxyl groups, χ OH,HEMA χ for HEMA,th The relationship can be expressed according to Equation 13:

[0105]

number

[0106] Molar fraction of HEMA in the polymer, χ HEMA,exp of the purified product by integrating the areas corresponding to the peaks of the diol moiety attached to the urethane bond and the methylene group of HEMA. 1 In embodiments where the chemical reactants include PEG, HDO, and HEMA, χ HEMA,exp can be calculated according to Equation 14.

[0107]

number

[0108] Here, "A HEMA,-CH2-CH2-OCONH- " can be centered at 4.32 ppm, and "A HDO,-CH2-OCONH- " can be at 4.03 ppm, and "A PEG,-CH2-OCONH- For polymers containing PCL, the signal of the polymer PCL and the HDO-based methylene group next to the urethane unit is1 Because of overlap in the H NMR spectrum, χ HEMA can be calculated according to Equation 15. PCL+HDO,-CH2-OCONH- " is 4.03 ppm, and "A HEMA,-CH2-CH2-OCONH- " can be located at 4.32 ppm.

[0109]

number

[0110] According to Carothers' equation, the number-average degree of polymerization (DPO) in the step-growth polymerization of difunctional monomers AA and BB is n is directly related to the extent of reaction and the stoichiometry between the functional groups according to Eq. 16.

[0111]

number

[0112] where "p" can be the degree of reaction and "r" can be the total functional groups (B)N present in excess. B The total number of functional groups (A)N that are under-represented relative to A The stoichiometric imbalance may be calculated by the ratio of

[0113] Incorporating a monofunctional compound B while maintaining a stoichiometric imbalance of 1 (e.g., 1 mol A-A, 0.95 mol B-B, 0.1 mol B) results in a reaction rate of 100% even if the reaction reaches completion. n In this case, the degree of polymerization is determined by the average functionality of the monomers in the system (f avg ) can be additionally relied upon.

[0114]

number

[0115] Here, "N i " is a sensuality "f i" is the amount of monomer "i" with p. Considering p, the X with a bar above n can be calculated according to Equation 18.

[0116]

number

[0117] "X with top bar n " and the molecular weight of the repeating unit "M ru " is used to calculate the number average molecular weight, M n can be obtained according to Equation 19.

[0118]

number

[0119] Here, "M ru " can be calculated by the feed ratio adjusted average of the molecular weights of the monomers. In various embodiments, HEMA can be used as the monofunctional alcohol. avg To reduce it to less than 2, we use M with an upper bar. n Equations 17 to 19 can be rewritten according to equations 20 to 23.

[0120]

number

[0121] Using Equation 14, M with an upper bar n and the molar fraction of HEMA hydroxyl groups among all hydroxyl groups in the system, which is expressed by Equations 25-26.

[0122]

number

[0123] If the polyaddition is carried out to quantitative monomer conversion, Equations 25 and 27 are expressed as χ HEMA or χOH,HEMA M with upper bar n This allows for a direct estimation of the limits of

[0124] In one or more embodiments, a solution containing low molecular weight diol 114, macrodiol 116, and HEMA can be introduced into one or more flow reactors 104 via a common inlet 106 (e.g., first inlet 106a). For example, in an N2-filled glovebox, a solution of PEG2000:HDO or PCL2000:HDO (40:60) and HEMA, having a total of 4.99 mmol of hydroxy groups, with 5 mol% of the hydroxy groups represented by HEMA, can be prepared by dissolving 1905 mg (0.95 mmol, 0.38 equivalents) of PEG2000 or 2156 mg (0.95 mmol, 0.38 equivalents) of PCL2000, 168 mg (1.42 mmol, 0.57 equivalents) of HDO, and 33 mg (0.25 mmol, 0.10 equivalents) of HEMA in anhydrous THF to a total volume of 5.5 mL. Additionally, a solution of diisocyanate monomer 118 can be introduced into the flow reactor 104 through another inlet 106 (e.g., second inlet 106b). For example, a 1.92 M MDI solution can be prepared by dissolving 625 mg (2.50 mmol, 1.00 equivalents) of MDI in anhydrous THF to a total volume of 1.3 mL. Also, a solution of catalyst 120 can be introduced into one or more flow reactors 104 through another inlet (e.g., third inlet 106c). For example, a 9.6×10 M MDI solution can be prepared by dissolving 625 mg (2.50 mmol, 1.00 equivalents) of MDI in anhydrous THF to a total volume of 1.3 mL. -2 A DBU solution of M can be prepared by dissolving 19.0 mg (0.13 mmol, 0.05 equivalents) in 1.3 mL of anhydrous THF. The retention time can be set to, for example, 120 seconds, 180 seconds, 240 seconds, and 300 seconds by changing the flow rate of each component. For example, Table 8 below shows the synthesis reaction conditions related to the above exemplary solutions and retention times.

[0125] [Table 8]

[0126] The reactions characterized in Table 8 were carried out for 1.5 residence times before collecting the product fractions. After every reaction, one or more flow reactors 104 can be purged with anhydrous THF. The crude sample can be precipitated in petroleum ether and dried under reduced pressure. 1 The product was analyzed by HNMR and GPC. A sample prepared with a 300 s residence time was redissolved in THF and precipitated twice in MeOH containing 4 vol% TFA. After filtration and drying under reduced pressure, the product was obtained as a white solid. 1 Further analysis was performed by HNMR, FTIR, and GPC. Figure 10 shows an exemplary, non-limiting graph 1002 that can show monomer conversion as a function of residence time for the synthesis of exemplary HEMA endcapped polyurethanes 102: FlowPU6 and FlowPU7. Line 1004 can represent FlowPU7, in which PCL2000 was employed as the macrodiol 116. Line 1006 can represent FlowPU6, in which PEG2000 was employed as the macrodiol 116.

[0127] In one or more embodiments, in an N2-filled glovebox, a solution of macrodiol 116, HDO (e.g., as low molecular weight diol 114), and HEMA can be prepared according to Table 9 below, with HEMA accounting for 5 mol% of the total alcohol groups. Additionally, all components can be dissolved in anhydrous THF. A 1.92 M MDI solution and 5 mol% DBU solution can also be prepared similarly.

[0128] [Table 9]

[0129] According to various embodiments described herein, the initial residence time was set to 210 seconds (e.g., total flow rate 224.3 μl / min), and reactant conversion rates were determined via one or more measurement devices 204. If the reactant conversion rates did not reach completion, the residence time was increased in 30-second increments (e.g., individual flow rates can be derived from Table 8). The output of the flow reactor 104 can be directly precipitated in petroleum ether and dried under reduced pressure. The crude sample can be dissolved in THF and precipitated twice in MeOH containing 4 vol% TFA. After filtration and drying under reduced pressure, a white solid is obtained. The product can be 1 H NMR, 13 The polyurethanes were analyzed by CNMR, FTIR, GPC, DSC, or a combination thereof. Additionally, Table 10, shown below, can provide additional experimental data for the exemplary HEMA endcapped polyurethane 102 synthesis described herein.

[0130] [Table 10]

[0131] In one or more embodiments, the HEMA end-capped polyurethane 102 can be further dissolved with AIBN to achieve crosslinking. For example, in a 25 mL glass vial, 2.00 g of polyurethane 102 examples FlowPU8-FlowPU11 and 30 mg of AIBN (1.5 wt%) can be dissolved in a minimal amount of THF at room temperature, and the solution can be transferred to a 5 cm diameter PTFE dish. After removing the solvent under reduced pressure, the sample can be heated to 80°C under a protective atmosphere and cured for 4 hours. In another example, 712.5 mg of polyurethane 102 example FlowPU9 (71 wt%) and 237.5 mg of butyl acrylate (BuAcr, 24 wt%) can be dissolved in a minimal amount of THF (~2 mL). 50 mg of AIBN (5 wt%) can be added, and the mixture can be heated to 80°C for 1 hour. The reaction mixture can then be cooled to room temperature, and the resulting gel can be washed and dried in vacuo.

[0132] 11 illustrates a flow diagram of an exemplary, non-limiting, computer-implemented method 1100 that may be employed by reactor control system 200 in accordance with one or more embodiments described herein. Repeated descriptions of similar elements employed in other embodiments described herein are omitted for the sake of brevity.

[0133] At 1102, the computer-implemented method 1100 may include, by a system (e.g., reactor control system 200) operatively coupled to a processor (e.g., included in one or more computing devices 208), measuring (e.g., via one or more measuring devices 204) reactant reaction rates of a polyurethane polymerization reaction (e.g., according to polymerization scheme 100) in one or more flow reactors 104. For example, the polyurethane polymerization reaction may include polymerization of one or more low molecular weight diols 114, macrodiols 116, diisocyanate monomers 118, organic catalysts 120, or combinations thereof, according to polymerization scheme 100 (e.g., as illustrated in Figures 1-2, or 7-8, or a combination thereof). Also, in one or more embodiments, the polymerization reaction may further include end-capping the resulting polyurethane 102 with HEMA (e.g., as illustrated in Figure 9). The measurements at 1102 can be performed by one or more measurement devices 204, which can be located adjacent to one or more flow channels 108 of the flow reactor 104, or can be in fluid communication with the flow reactor 104, or both. In various embodiments, the reactant conversion rates can be measured by analytical techniques including, but not limited to, FTIR spectroscopy, NMR spectroscopy, ultraviolet-visible-near-infrared (UV-Vis-NIR) absorption, in-line viscometers, refractive index, gas chromatography, or combinations thereof.

[0134] At 1104, computer-implemented method 1100 may include employing, by the system (e.g., via computing device 208), one or more computer models to determine a target residence time associated with the polymerization reaction based on the reactant reaction rates. For example, employing one or more computer models at 1104 may be performed according to control scheme 500 or 600, or a combination thereof.

[0135] At 1106, the computer-implemented method 1100 can include adjusting, by the system, the flow rates of chemical reactants in the flow reactor 104 (e.g., via one or more PID controllers 202) based on the measurements at 1102 to achieve a target polyurethane 102 structure, where the adjustments at 1106 can result in the target residence time determined at 1104. For example, one or more PID controllers 202 can operate one or more inlets 106 of the flow reactor 104 to adjust the flow rates to achieve the target residence time determined via one or more computer models. For example, one or more PID controllers 202 can control one or more pumps for one or more inlets 106. In another example, one or more PID controllers 202 can control the duration for which one or more inlets 106 remain open or closed. In various embodiments, the flow rate adjusted at 1106 can be the flow rate of the low molecular weight diol 114, the flow rate of the macrodiol 116, the flow rate of the diisocyanate monomer 118, the flow rate of the catalyst 120, the flow rate of the HEMA, or a combination thereof, etc.

[0136] Also, in various embodiments, one or more chemical reactants of a polyurethane polymerization reaction can be synthesized in one or more flow reactors 104. Furthermore, the computer-implemented method 1100 can further control the reactant synthesis reaction. For example, the computer-implemented method 1100 can include, by the system, measuring a reactant reaction rate of the reactant synthesis reaction in the flow reactor 104 (e.g., via the second measurement device 204b). The computer-implemented method 1100 can also include, by the system, employing one or more computer models (e.g., via one or more computing devices 208) to determine a target residence time associated with the reactant synthesis reaction based on the reactant reaction rate. Furthermore, the computer-implemented method 1100 can include, by the system, adjusting a flow rate of one or more second chemical reactants in the flow reactor 104 (e.g., via one or more PID controllers 202). For example, the reactant synthesis reaction can synthesize one or more macrodiols 116 employed in a polyurethane polymerization reaction (e.g., as illustrated in FIGS. 7-8 ).

[0137] 12 and the following discussion are intended to provide a general description of a suitable computing environment 1200 in which various embodiments of one or more computing devices 208 described herein may be implemented. While the embodiments have been described above in the general context of computer-executable instructions executable on one or more computers, those skilled in the art will recognize that the embodiments may also be implemented in combination with other program modules, or as a combination of hardware and software, or both.

[0138] Generally, program modules include routines, programs, components, data structures, or combinations thereof that perform particular tasks or implement particular abstract data types. Those skilled in the art will also appreciate that the methods of the present invention can be practiced with other computer system configurations, including single-processor or multi-processor computer systems, minicomputers, mainframe computers, Internet of Things ("IoT") devices, distributed computing systems, as well as personal computers, handheld computing devices, microprocessor-based or programmable consumer electronics, and the like, each of which can be operatively coupled to one or more associated devices.

[0139] The illustrated embodiments may also be practiced in distributed computing environments where certain tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. For example, in one or more embodiments, computer-executable components may execute from memory that may include or consist of one or more distributed memory units. As used herein, the terms "memory" and "memory unit" are interchangeable. Furthermore, one or more embodiments described herein may execute code of computer-executable components in a distributed manner, e.g., multiple processors coupled or cooperating to execute code from one or more distributed memory units. As used herein, the term "memory" may encompass a single memory or memory unit in one location or multiple memories or memory units in one or more locations.

[0140] A computing device typically includes a variety of media, which may include a computer-readable storage medium, a machine-readable storage medium, a communication medium, or a combination thereof, and these two terms are used interchangeably herein as follows. A computer-readable storage medium or a machine-readable storage medium may be any available storage medium that can be accessed by a computer, and includes both volatile and nonvolatile media, removable and non-removable media. By way of example and not limitation, a computer-readable storage medium or a machine-readable storage medium may be implemented in connection with any method or technology for storing information, such as computer-readable or machine-readable instructions, program modules, structured or unstructured data, etc.

[0141] A computer-readable storage medium includes, but is not limited to, random access memory ("RAM"), read-only memory ("ROM"), electrically erasable programmable read-only memory ("EEPROM"), flash memory or other memory technology, compact disc read-only memory ("CD-ROM"), digital versatile disc ("DVD"), Blu-ray disc ("BD") or other optical disc storage, magnetic cassette, magnetic tape, magnetic disc storage or other magnetic storage device, solid-state drive or other solid-state storage device, or other tangible medium, non-transitory medium, or combination thereof, that can be used to store the desired information. In this regard, the terms "tangible" or "non-transitory" as applied to storage, memory, or computer-readable medium in this specification are understood to exclude, as modifiers, only transitory signals that propagate themselves, and are not intended to waive all standard storage, memory, or computer-readable medium that are not only transitory signals that propagate themselves.

[0142] The computer-readable storage medium can be accessed by one or more local or remote computing devices for various operations on the information stored by the medium, for example, via access requests, queries, or other data retrieval protocols.

[0143] Communication media typically embodies computer-readable instructions, data structures, program modules, or other structured or unstructured data in a data signal (e.g., carrier wave or other transport mechanism), such as a modulated data signal, and includes any information delivery or transport media. The term "modulated data signal" or signal refers to a signal that has one or more characteristics set or changed in such a manner as to encode information in the signal or signals. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media.

[0144] 12, an exemplary environment 1200 for implementing various embodiments of the aspects described herein includes a computer 1202, which includes a processing unit 1204, a system memory 1206, and a system bus 1208. The system bus 1208 couples system components, including but not limited to the system memory 1206, to the processing unit 1204. The processing unit 1204 may be any of a variety of commercially available processors. Dual microprocessors and other multi-processor architectures may also be employed as the processing unit 1204.

[0145] The system bus 1208 can be any of several types of bus structures that can be further interconnected to a memory bus (with or without a memory controller), a peripheral bus, and a local bus using any of a variety of commercially available bus architectures. The system memory 1206 includes a ROM 1210 and a RAM 1212. The basic input / output system ("BIOS") can be stored in non-volatile memory such as a ROM, erasable programmable read-only memory ("EPROM"), or EEPROM, and contains the basic routines that help to transfer information between elements within the computer 1202, such as during start-up. The RAM 1212 can also include a high-speed RAM such as static RAM for caching data.

[0146] Computer 1202 further includes an internal hard disk drive (“HDD”) 1214 (e.g., EIDE, SATA), one or more external storage devices 1216 (e.g., a magnetic floppy disk drive (“FDD”) 1216, a memory stick or flash drive reader, a memory card reader, or a combination thereof, etc.), and an optical disk drive 1220 (e.g., an optical disk drive that can read from or write to CD-ROM disks, DVDs, BDs, or a combination thereof, etc.). While internal HDD 1214 is illustrated as being located within computer 1202, internal HDD 1214 may also be configured for external use in a suitable enclosure (not shown). Also, although not shown in environment 1200, a solid state drive (“SSD”) may be used in addition to or in place of HDD 1214. HDD 1214, external storage device(s) 1216, and optical disk drive 1220 can be connected to system bus 1208 by HDD interface 1224, external storage device interface 1226, and optical drive interface 1228, respectively. Interface 1224 for external drive implementations may include Universal Serial Bus ("USB") and / or Institute of Electrical and Electronics Engineers ("IEEE") 1394 interface technologies. Other external drive connection technologies are contemplated by the embodiments described herein.

[0147] The drives and their associated computer-readable storage media provide non-volatile storage of data, data structures, computer-executable instructions, etc. To the computer 1202, the drives and storage media accommodate the storage of any data in a suitable digital format. While the above description of computer-readable storage media refers to each type of storage device, those skilled in the art will understand that other types of computer-readable storage media, whether currently existing or developed in the future, can be used in the exemplary operating environment, and further, any such storage media can include computer-executable instructions for performing the methods described herein.

[0148] A number of program modules can be stored in the drives and RAM 1212, including an operating system 1230, one or more application programs 1232, other program modules 1234, and program data 1236. All or portions of the operating system, applications, modules, data, or any combination thereof, may also be cached in RAM 1212. The systems and methods described herein can be implemented using various commercially available operating systems or combinations of operating systems.

[0149] Computer 1202 may optionally include emulation technology. For example, a hypervisor (not shown) or other intermediary may emulate a hardware environment for operating system 1230, and the emulated hardware may optionally differ from the hardware depicted in FIG. 12 . In such an embodiment, operating system 1230 may include one virtual machine (“VM”) among multiple VMs hosted on computer 1202. Additionally, operating system 1230 may provide a runtime environment, such as the Java Runtime Environment or the .NET Framework, for application 1232. A runtime environment is a consistent execution environment that allows application 1232 to run on any operating system that includes the runtime environment. Similarly, operating system 1230 may support containers, and application 1232 may be in the form of a container, which is a lightweight, standalone, executable software package that includes, for example, code, runtime, system tools, system libraries, and settings for the application.

[0150] Additionally, computer 1202 can enable a security module, such as a Trusted Processing Module ("TPM"). For example, with a TPM, a boot component temporally hashes the next boot component and waits for the result to match a secure value before loading the next boot component. This process can occur at any layer within the code execution stack of computer 1202 and can be applied, for example, at the application execution level or the operating system ("OS") kernel level, thereby enabling security at any level of code execution.

[0151] A user can enter commands and information into the computer 1202 through one or more wired / wireless input devices, such as a keyboard 1238, a touchscreen 1240, and a pointing device (e.g., a mouse 1242). Other input devices (not shown) can include a microphone, an infrared ("IR") remote control, a radio frequency ("RF") remote control, or other remote control, a joystick, a virtual reality controller and / or headset, a gamepad, a stylus pen, an image input device (e.g., camera(s)), a gesture sensor input device, a visual motion sensor input device, an emotion or face detection device, or a biometric input device (e.g., a fingerprint or iris scanner). These and other input devices are often connected to the processing unit 1204 through an input device interface 1244, which can be coupled to the system bus 1208, but can also be connected by an interface such as a parallel port, an IEEE 1394 serial port, a game port, a USB port, an IR interface, a BLUETOOTH interface, or a combination thereof.

[0152] A monitor 1246 or other type of display device can also be connected to the system bus 1208 via an interface, such as a video adapter 1248. In addition to the monitor 1246, computers typically include other peripheral output devices (not shown), such as speakers, printers, or a combination thereof.

[0153] The computer 1202 can operate in a networked environment using logical connections via wired, wireless communications, or a combination thereof, to one or more remote computers, such as remote computer(s) 1250. The remote computer(s) 1250 can be a workstation, a server computer, a router, a personal computer, a portable computer, a microprocessor-based entertainment appliance, a peer device, or other common network node, and typically includes many or all of the elements described above relative to the computer 1202, although for simplicity, only memory / storage 1252 is illustrated. The logical connections depicted include wired / wireless connections to a local area network (“LAN”) 1254, a larger network (e.g., a wide area network (“WAN”) 1256), or a combination thereof. Such LAN and WAN networking environments are commonplace in offices and businesses, facilitating enterprise-wide computer networks, such as intranets, all of which may connect to a global communications network, e.g., the Internet.

[0154] When used in a LAN networking environment, the computer 1202 can be connected to the local network 1254 through either or both a wired and wireless communication network interface or adapter 1258. The adapter 1258 can facilitate wired or wireless communication to the LAN 1254, and the LAN 1254 can also include a wireless access point (“AP”) disposed thereon for communicating with the adapter 1258 in a wireless mode.

[0155] When used in a WAN networking environment, the computer 1202 may include a modem 1260 or may be connected to a communications server on the WAN 1256 via other means for establishing communications over the WAN 1256, such as via the Internet. The modem 1260 may be internal or external, a wired or wireless device, and may be connected to the system bus 1208 via the input device interface 1244. In a networked environment, program modules depicted relative to the computer 1202, or portions thereof, may be stored in the remote memory / storage device 1252. It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between computers may be used.

[0156] When used in either a LAN or WAN network environment, computer 1202 can access a cloud storage system or other network-based storage system in addition to, or instead of, the above-mentioned external storage device 1216. Generally, the connection between computer 1202 and a cloud storage system can be established with respect to LAN 1254 or WAN 1256, for example, by adapter 1258 or modem 1260, respectively. Upon connecting computer 1202 to an associated cloud storage system, external storage interface 1226, with the aid of adapter 1258, modem 1260, or a combination thereof, can manage the storage provided by the cloud storage system in the same way as other types of external storage. For example, external storage interface 1226 can be configured to provide access to cloud storage sources as if the cloud storage sources were physically connected to computer 1202.

[0157] The computer 1202 may be operable to communicate with any wireless device or entity operatively positioned for wireless communication, such as a printer, a scanner, a desktop and / or portable computer, a portable data assistant, a communications satellite, any equipment or location associated with a wirelessly detectable tag (e.g., a kiosk, a newsstand, a store shelf, or a combination thereof), and a telephone. This can include Wireless Fidelity ("Wi-Fi") and BLUETOOTH® wireless technologies. Thus, communication can be in a predefined structure, such as a traditional network, or simply ad-hoc communication between at least two devices.

[0158] The foregoing includes merely exemplary systems, computer program products, and computer-implemented methods. Of course, for purposes of describing this disclosure, it is not possible to describe every conceivable combination of components, products, computer-implemented methods, or combinations thereof; however, one skilled in the art will recognize that many further combinations and permutations of the present disclosure are possible. Furthermore, to the extent that terms such as "comprising," "having," or "possessing" are used in the detailed description, claims, appendices, and drawings, such terms are intended to be inclusive in the same manner as the term "comprising" interpreted when employed as a transitional term in a claim. The description of various embodiments has been presented for purposes of illustration, but is not intended to be exhaustive or to be limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the described embodiments. The terminology used herein was selected to best explain the principles of the embodiments, practical applications, or technical improvements relative to technologies found in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for synthesizing polyurethane by a polymerization reaction carried out in a flow reactor having multiple reactor loops, the polymerization reaction polymerizing a diol with a diisocyanate monomer, the synthesizing further comprising: supplying the diol to the flow reactor through a first inlet; supplying the diisocyanate monomer to the flow reactor through a second inlet; and supplying an organic catalyst to the flow reactor through a third inlet; introducing anhydrous tetrahydrofuran (THF) into the flow reactor through a fourth inlet at a point downstream of one or more reactor loops of the plurality of reactor loops; A method comprising:

2. The method of claim 1 , wherein the polymerization reaction further comprises polymerizing a second diol with the diisocyanate monomer.

3. the diol is selected from the group consisting of 1,6-hexanediol, 1,8-octanediol, and diethylene glycol; the diisocyanate monomer is selected from the group consisting of 4,4'-methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; the polymerization reaction comprises a catalyst selected from the group consisting of 8-diazabicyclo[5.4.0]undec-7-ene, dibutyltin dilaurate, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and yttrium(III) isopropoxide; the second diol is selected from the group consisting of polyethylene glycol, polycaprolactone diol, polylactide diol, poly(carbo)siloxane diol, and polyvalerolactone diol; The method of claim 2.

4. 3. The method of claim 2, wherein the second diol is synthesized by a second polymerization reaction carried out in the flow reactor.

5. 5. The method of claim 4, wherein the second polymerization reaction is a ring-opening polymerization of a cyclic monomer in the presence of an initiator and a urea catalyst.

6. the cyclic monomer is selected from the group consisting of ε-caprolactone, lactide, valerolactone, cyclic carbonates, and cyclic (carbo)siloxanes; the initiator is selected from the group consisting of 1,8-octanediol, 1,6-hexanediol, and diethylene glycol; the urea catalyst is selected from the group consisting of 1,3-bis[3,5-bis(trifluoromethyl)phenyl]urea, 1-[3,5-bis(trifluoromethyl)phenyl]-3-[4-(trifluoromethyl)phenyl]urea, N-[3,5-bis(trifluoromethyl)-phenyl]-N'-phenylurea, N-[3,5-bis(trifluoromethyl)phenyl]-N'-cyclohexylurea, 1-phenyl-3-(3-(trifluoromethyl)phenyl)urea, 1,3-diphenylurea, 1-cyclohexyl-3-phenylurea, and the respective thioureas; The method of claim 5.

7. The diol selected from the group consisting of 1,6-hexanediol, 1,8-octanediol, and diethylene glycol; the diisocyanate monomer is selected from the group consisting of 4,4'-methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; the polymerization reaction comprises a catalyst selected from the group consisting of 8-diazabicyclo[5.4.0]undec-7-ene, dibutyltin dilaurate, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and yttrium(III) isopropoxide; The method of claim 1.

8. 10. The method of claim 1, wherein the polymerization reaction further comprises polymerizing the diol and diisocyanate monomers with 2-hydroxyethyl methacrylate, and wherein end cap groups derived from the 2-hydroxyethyl methacrylate are disposed at the ends of the polymer backbone of the polyurethane as a result of the synthesis.

9. 10. The method of claim 1, further comprising generating a reaction rate value for a reactant based on a Fourier transform infrared spectrum generated by a measurement device in fluid communication with the flow reactor.

10. 10. The method of claim 9, further comprising employing, by a processor, a computer model to identify a target residence time associated with the polymerization reaction based on the reaction rate values ​​of the reactants.

11. 11. The method of claim 10, further comprising modifying the synthesis by adjusting the flow rate in the flow reactor via a proportional-integral-derivative controller based on the target residence time.

12. Controlling, by a system operatively coupled to a processor, one or more proportional integral derivative ("PID") controllers for supplying a diol to a flow reactor having multiple reactor loops, wherein polyurethane is synthesized in the flow reactor by a polymerization reaction, the polymerization reaction polymerizing the diol with a diisocyanate monomer, said synthesizing comprising supplying the diol to the flow reactor through a first inlet, supplying the diisocyanate monomer to the flow reactor through a second inlet, and supplying an organic catalyst to the flow reactor through a third inlet; measuring the reaction rate of the reactants of the polymerization reaction in the flow reactor with the system; adjusting, by the system, flow rates of chemical reactants in the flow reactor based on the measurements to achieve a target polyurethane structure, wherein adjusting the flow rates includes introducing anhydrous tetrahydrofuran (THF) into the flow reactor through a fourth inlet at a point downstream of one or more reactor loops of the plurality of reactor loops; 11. A computer-implemented method comprising:

13. 13. The computer-implemented method of claim 12, further comprising employing, by the system, a computer model to determine a target residence time associated with the polyurethane polymerization reaction based on the reaction rates of the reactants, wherein adjusting the flow rates results in the target residence time.

14. 14. The computer-implemented method of claim 13, wherein measuring the reaction rate of the reactants is performed by at least one analytical technique selected from the group consisting of Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, in-line viscometer, gas chromatography, and ultraviolet-visible absorption spectroscopy.

15. A flow reactor for carrying out a polyurethane polymerization reaction according to the method of any one of claims 1 to 11; a measuring device for determining a reaction rate value of the reactants of the polyurethane polymerization reaction in the flow reactor; a computing device for controlling the polyurethane polymerization reaction based on the reaction rate values ​​of the reactants by adjusting the flow rates in the flow reactor; A system that includes:

16. 16. The system of claim 15, further comprising a proportional-integral-derivative controller operably coupled to the computing device and controlling operation of the inlet of the flow reactor.

17. 17. The system of claim 16, wherein the computing device employs a computer model to determine a target residence time associated with a polyurethane polymerization reaction based on the reaction rate values ​​of the reactants.

18. 16. The system of claim 15, wherein the flow rate is relative to a diol reactant of the polyurethane polymerization reaction in the flow reactor.

19. 16. The system of claim 15, wherein the flow rate is relative to a diisocyanate reactant of the polyurethane polymerization reaction in the flow reactor.

20. A computer program comprising program code adapted to perform the method steps according to any one of claims 1 to 11, when the computer program is run on a computer.

21. A computer program comprising program code adapted to perform the computer-implemented method steps of any one of claims 12 to 14 when the computer program is run on a computer.

Images