Synthesis of polyethylene-polyacrylate block copolymers in continuous flow

Abstract

A system for preparing block copolymers comprising a polyolefin block and a polar polymer block by a continuous droplet flow method is disclosed. The continuous droplet flow method combines coordination-insertion polymerization of a gaseous olefin monomer that is dissolved in droplets of a solvent using a diamine coordinated Pd(II) catalyst complex with Metal-organic Insertion Light-initiated Radical polymerization of a polar monomer, such as an acrylate or (meth)acrylate, using the same catalyst and an auxiliary complexing ligand. Polyolefin-polar block copolymers prepared using the disclosed method can be a diblock copolymer comprising a polyolefin block and a polar polymer block, (e.g. a polyethylene-polyacrylate or a polyethylene-poly(meth) acrylate diblock copolymer), or a triblock copolymer (e.g. a polyacrylate-polyethylene-polyacrylate or a poly(meth)acrylate-polyethylene-poly(meth)acrylate copolymer).

Description

Synthesis of polyethylene-polyacrylate block copolymers in continuous flowFIELD

[0001] The subject matter disclosed herein relates to polyethylene-polyacrylate (PE-PA) and polyacrylate-poly ethylene-polyacrylate (PA-PE-PA) block copolymer compounds and methods and apparatus for preparing them in continuous flow.STATEMENT OF GOVERNMENT INTEREST

[0002] This invention was made in part with government support under grant CHEM- 2108576, awarded by the National Science Foundation. The government has certain rights in the invention.BACKGROUND

[0003] Continuous flow synthesis offers several advantages over traditional batch syntheses, such as high precision, excellent reproducibility, constant temperature conditions, and enhanced safety when handling hazardous chemicals.1-7In addition, the uninterrupted operation of continuous flow reactors enables large-scale production, ranging from milligrams to kilograms of materials utilizing the same equipment. Conversely, upscaling in conventional batch processes often requires the installation of new equipment, and in some cases, it can be detrimental to overall product quality.4,6,8

[0004] The utilization of flow chemistry has revolutionized drug development and translated organic small-molecule synthesis to the industrial scale.9'11However, synthesizing macromolecules in continuous flow imposes a higher level of complexity as the fluid dynamics in the tubular reactor influence the structure and composition of polymer segments.12-14Due to the higher viscosity of typical polymer solutions, the velocity profile of polymerization reactions forms a greater parabolic laminar flow with broader residence times distribution (RTD) compared to analogous small molecule reactions and affects the conversion of monomers, molecular weight (M ), and dispersity (£>) of polymers.15'18Therefore, often higher dispersity is observed compared to batch polymerization.I2-19-23To retain the narrow dispersity of chain polymerizations, all chains need to experience the same conditions, which is challenging to achieve in the laminar flow.12,15,24To remedy these shortcomings, a plug-flow system in which a droplet flow is maintained will allow for more uniform reaction conditions to result in a narrow RTD.25,26Here, a gaseous phase confines the liquid reaction droplets and affords a circulating homogenous reaction pattern to yield well- controlled polymerization.12,15,25,27,28For instance, during a photoinduced electron / energy transfer reversible addition-fragmentation transfer (PET-RAFT) polymerization in droplet flow, Boyer et al. observed a significant increase in the consistency of monomer conversion, composition, and dispersity in the produced polymers over time compared to traditional continuous flow.15Leibfarth and coworkers demonstrated that using the droplet flow for chain reactions in the case of RAFT and ring-opening polymerization (ROP) showed dispersity values that matched with polymerizations conducted in the small-scale batches.12The advantages of a droplet flow have also been investigated with immiscible solvent combinations to isolate the reaction droplet for homo- and copolymerization of polyacrylates.24,29,30

[0005] However, block copolymer (BCP) synthesis is regularly conducted in laminar flow systems, using the same polymerization mechanism, for example, controlled radical polymerization (CRP),31'40ionic polymerization,41'45and ring-opening polymerization (ROP)46'48throughout adding one monomer after another in a linear setup of reactors. (See, e.g. Fig. 1 A.) The increasing viscosity and resulting increasing dispersity are mostly maintained by keeping the molecular weights of the di -and multiblocks in low molecular weight regions, ranging for example, from 1-10 ka.2- -43-47-49-?0In addition, a combination of polymerization methods in which one block is prepared through a polymerization technique different from the second block is limited. Junkers and co-workers showed such BCP preparation by combining different methods of CRP, in which one polymer segment is prepared by either atom transfer radical polymerization (ATRP) or reversible additionfragmentation transfer polymerization (RAFT) with subsequent end-functionalization, and then prepared blocks were combined by click chemistry to form di-block copolymers.51Inanother example, Zhu et al. synthesized poly(e-caprolactone)-Z>-poly(N-vinylpyrrolidone) through sequential ROP and free radical polymerization (FRP).52However, there is no example known in which coordination insertion and free radical polymerization have been combined in the continuous flow to form polar polyolefin block copolymers (see, Figure IB).

[0006] One of the challenges to combining such pathways is the adverse properties of the involved monomer families, gaseous olefins, and liquid acrylates. There has been no investigation using the gaseous mobile phase as a monomer carrier and facilitating at the same time a droplet flow in which the monomers in the gaseous phase participate in chemical transformation themselves (Figure ID). Gaseous monomers have not been translated to the continuous flow, and only tubular reactors53'55and fluidized-bed reactors’6,57for high- temperature free radical reactions are known for making polyolefins on an industrial scale.

[0007] Also, using the same polymerization technique for forming both blocks of a diblock polymer will utilize the monomers of same family. On the other hand, combining two different polymerization mechanisms for synthesizing the block copolymers, as is disclosed herein, opens paths for using monomers of different categories with different physical and chemical properties, broadening the kinds of block copolymers that can be easily made.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 illustrates a schematic of polymerization in continuous flow. (A) compared to (B) shows a comparison of di-block copolymer synthesis using the same or different polymerization pathways for both blocks; (C) compared to (D) shows how the gas phase is utilized in gas-liquid droplet flow systems in previous work compared to the present disclosure.

[0009] Figure 2 illustrates synthesis of polyethylene (PE) homopolymer in a continuous flow reactor;(A) Reaction scheme of Coordination-Insertion Polymerization of ethylene utilizing Cl catalyst;(B) Schematic diagram of the continuous flow reactor for ethylene polymerization;(C) GPC traces of PE homopolymers of Table 1, entries 1 through 7.

[0010] Figure 3 shows a kinetic study of polyethylene (PE) homopolymerization based on residence time controlled by the flow rate of catalyst solution; (A) gel permeation chromatography (GPC) traces of PE homopolymers for different residence times (residence times of 3, 4, 6, 12 and 21 minutes are indicated at the upper right of the figure); (B) number average (Mn) vs. residence time plot evidencing living polymerization of ethylene.

[0011] Figure 4 illustrates synthesis of poly(methyl acrylate) (PMA) homopolymer in the continuous flow reactor;(A) shows a reaction scheme for light-initiated free radical polymerization of methyl acrylate employing the Cl catalyst.(B) is a schematic diagram of the continuous flow reactor for methyl acrylate polymerization.(C) shows GPC traces of polymethacrylate (PMA) homopolymers of Table 5, entries 1 through 6.

[0012] Figure 5 shows a kinetic study of PMA homopolymerization based on residence time varied by controlling the flow rate of feed solutions; (A) GPC traces of PMA homopolymers for different residence times; (B) Mn vs. residence time plot illustrates the increase in molecular weight of the polymer in relation to residence time.

[0013] Figure 6 is a schematic diagram of the synthesis of polyethylene-polyacrylate block copolymer (PE- / 1-PMA) in a continuous flow reactor. Schematics of reactions occurring in the droplet phase of each stage of the continuous flow reactor are shown above the stage.

[0014] Figure 7 shows characterization of synthesized PE- / 1-PMA (i.e. entry 1, Table 8) in the continuous flow reactor;(A) GPC traces of crude PE-b-PMA, PE homopolymer, and purified PE-Zi-PMA;(B) DOSY 1H NMR spectrum in TCE (C2D2C14) at 25 °C of purified PE-i-PMA;(C) SAXS data shows principal scattering peaks of purified PE-Zi-PMA;(D) DSC of PE-A-PMA purified product.

[0015] Figure 8. Proposed mechanism of Coordination-Insertion Polymerization of ethylene.74

[0016] Figure 9. 'H NMR spectrum (400 MHz, CDCh, 25 °C) of polyethylene (PE) homopolymer entry 3, Table 1.

[0017] Figure 10. DSC traces of polyethylene (PE) homopolymer entry 3, Table 1.

[0018] Figure 11. GPC traces of PE homopolymers in batch and flow reactor from Table3.

[0019] Figure 12. Proposed mechanism of Metal-organic insertion light initiated radical (MILRad) polymerization.71’72’75

[0020] Figure 13.XH NMR spectrum (400 MHz, CDCI3, 25 °C) of polymethyl acrylate (PMA) homopolymer entry 2, Table 5.

[0021] Figure 14. DSC traces of polymethyl acrylate (PMA) homopolymer entry 2, Table 5.

[0022] Figure 15. GPC traces of PMA homopolymers in batch and flow reactor from Table 6.

[0023] Figure 16. Proposed mechanism of polyethylene-polyacrylate block copolymer synthesis.75

[0024] Figure 17. Mechanism of radical trapping experiment of PE-MA macro-initiating radical in the presence of TEMPO75(top), and a schematic of the flow reactor for the experiment (bottom).

[0025] Figure 18. (Top) General structures for the products generated in the radical trapping experiment using TEMPO. (Bottom) 'H NMR spectrum (400 MHz, CDCI3, 25 °C) of polyethylene-methyl acrylate-TEMPO (PE-MA-TEMPO) polymer. The insert shows the signals confirming the TEMPO species attached to the polymer.

[0026] Figure 19. GPC traces of a) PE-b-PMA polymer, entry 2 of Table 8, b) PE-b-PMA polymer, entry 3 of Table 8, c) PE-b-PMA polymer, entry 4 of Table 8, d) PE-b-PEA polymer, entry 5 of Table 8, e) PE-b-P(n-BuA) polymer, entry 6 of Table 8, f) PE-b-P(Z-BuA) polymer, entry 7 of Table 8.

[0027] Figure 20. ' H NMR of PE-b-PMA purified product in CDCI3 at 25 °C (entry 1, Table 8).

[0028] Figure 21.XH NMR of PE-A-PMA purified product in CDCh at 25 °C (entry 2, Table 8).

[0029] Figure 22.XH NMR of PE-A-PMA purified product in CDCI3 at 25 °C (entry 3, Table 8).

[0030] Figure 23.XH NMR of PE-A-PMA purified product in CDCI3 at 25 °C (entry 4, Table 8).

[0031] Figure 24.NMR of PE-NPEA purified product in CDCh at 25 °C (entry 5, Table 8).

[0032] Figure 25.NMR of PE- / ?-P( / ?-BuA) purified product in CDCh at 25 °C (entry6, Table 8)

[0033] Figure 26.NMR of PE- / ?-P( / -BuA) purified product in C2D2CI4 at 25 °C (entry7, Table 8)

[0034] Figure 27. DOSYNMR spectrum of PE-A-PMA purified product in TCE (C2D2CI4) at 25 °C (entry 2, Table 8).

[0035] Figure 28. DOSYNMR spectrum of PE- / 1-PEA purified product in TCE (C2D2CI4) at 25 °C (entry 5, Table 8).

[0036] Figure 29. DOSYNMR spectrum of PE- / ?-P( / / -BuA) purified product in TCE (C2D2CI4) at 25 °C (entry 6, Table 8).

[0037] Figure 30. DSC traces of a) PE-NPMA polymer, entry 2 of Table 8, b) PE-A-PMA polymer, entry 3 of Table 8, c) PE-A-PMA polymer, entry 4 of Table 8, d) PE-A-PEA polymer, entry 5 of Table 8, e) PE- / >-P(w-BuA) polymer, entry 6 of Table 8, f) PE- / >-P( / -BuA) polymer, entry 7 of Table 8.

[0038] Figure 31. SAXS data shows the principal scattering peaks of a) PE-b-PMA polymer, entry 2 in Table 8, and b) PE-b-P(n-BuA) polymer, entry 6 in Table 8.DETAILED DESCRIPTION

[0039] Polyethylene is one of the most used commodity plastics. However, no route of continuous flow synthesis is of polyethylene is available industrially so far. Currently, only high-temperature free radical polymerization in tubular or fluidized-bed is utilized inindustrial scale. However, these approaches are unable to synthesize polymers with good control of desired branching density, length and molecular weight.

[0040] On the other hand, coordination-insertion polymerization in continuous flow ensures better control over the branching density, chain length and molecular weight of the polymers.

[0041] A heterogeneous droplet flow system is described herein that carries monomers in both the gaseous and liquid phases separately to promote the formation of block copolymers (BCPs) containing polyolefin, e.g. polyethylene (PE) and a polar polymer, e.g. polyacrylate (PA) segments (Figures IB & ID). This is realized by a method which allows for a switching of the insertion pathway forming the polyolefin and initiating the radical pathways in a single catalytic system. This mechanism employs Metal-organic Insertion Light-initiated Radical (MILRad) polymerization.58'61Here, a cationic diimine Pdll complex facilitates the living coordination-insertion polymerization (CIP) to synthesize a PE block. Subsequently, a Pd-PE- macrochelate is formed after the insertion of an acrylate monomer, which generates a macroradical species through the homolytic cleavage of Pd-C upon blue light irradiation (for example about 457 nm) to initiate free radical polymerization (FRP) in the presence of excess acrylate monomers which forms the second block of PE- / 1-PA di -block copolymers. A single catalyst mediates CIP and FRP sequentially, eliminating the need for multistep syntheses involving post-functionalization processes.

[0042] H. Dau et al. JACS 2020 vol. 142:21469-21483, Dual Polymerization Pathway for Polyolefin-Polar Block Copolymer Synthesis via MILRad: Mechanism and Scope; andUS Patent 11987652, to Harth et al., entitled “Light as Catalytic Switch: Metal-Organic Insertion / Light Initiated Radical (MILRAD) Polymerization” describe the MILRad synthesis of PE-PA and PA-PE-PA (and other) block copolymers of various composition utilizing a variety of diamine (Pd) complex catalysts, reaction solvents, ancillary ligands, olefin monomers, acrylate monomers, reactant concentrations and reaction conditions in “one-pot” synthetic methods in the liquid phase. These references are hereby incorporated by reference in their entirety and for all purposes.

[0043] Presently application of MILRad synthesis in a gas-liquid continuous droplet flow reaction format is described. Without being bound by any theory of the invention, the presently disclosed gas-liquid continuous droplet flow format, especially when performed in a tubular reactor, provides better mixing of the gaseous olefin monomer with the catalyst and reactants in the liquid phase, and as well alleviates the spread in reaction mixture velocity across the reactor cross section of the prior art laminar flow methods. This results in, among other advantages, a narrower poly dispersity of the diblock copolymer product.

[0044] Furthermore, the batch reactor embodiments described in the prior art require long reaction times, on the order of 5-15 hours, to achieve good conversion of monomer into the different polymer blocks. On the other hand, the presently-described apparatus and methods permit the completion of the polymerization reactions in just a few minutes.

[0045] In the working examples below, first polyethylene (PE) homopolymerization through CIP utilizing a Brookhart type a-diimine Pdll complex (Cl) in a continuous flow reactor (Figure 2) is performed, with a detailed kinetic investigation varying the system's parameters to establish a window of the olefin living polymerization. Using a droplet flow system, in which the gaseous phase contains ethylene, the effect of residence time, gas flow rate, gas pressure, and catalyst concentration on PE polymerization is investigated. It is shown that each parameter can adjust the molecular weight and yield and influences polymerization at the gas-liquid droplet interface.

[0046] Second, light-initiated radical (LRad) polymerization of methyl acrylate (MA) and its kinetic behavior employing the same catalyst in the liquid phase of a continuous flow system is exemplified. Here, in laminar flow, the influence of residence time and concentrations of monomer and catalyst on the molecular weight and yield of poly(methyl acrylate) (PMA) is examined.

[0047] Then, a sequential combination of these flow systems is adopted to merge these two reaction pathways and form the polyethylene-poly(methyl acrylate) block copolymer BCP (PE-A-PMA). Pd-PE-macrochelate opening and faster radical initiation is evaluated through the presence of additional quantities of ancillary ligand. A radical trapping experiment is carried out in the presence of MA and TEMPO to validate the formation of thePE radical macroinitiators. Several PE- >-PAs are synthesized in working examples, establishing a new route for preparing advanced polymeric materials, such as polar polyolefin block copolymers.

[0048] As used herein, the terms "about" or "approximately" for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, "about" or "approximately" may refer to the range of values ±10% of the recited value, e.g. "about 90%" may refer to the range of values from 81% to 99%.

[0049] As used herein, the term “residence time” refers to the time a reagent or reactant spends inside a flow reactor during a chemical reaction.

[0050] As used herein, the term “a gas phase and a liquid phase in reactive communication” means a gas phase in contact with a liquid phase wherein molecules of a gaseous monomer can diffuse into the liquid phase (“partition”) so as to react with a catalyst in the liquid phase to polymerize. In embodiments herein a gas phase and a liquid phase in reactive communication typically takes the form of liquid drops within a tube-shaped reactor or a transport line of an apparatus separated from one another by gas bubbles. The gas bubbles comprise or consist of a gaseous monomer and the liquid drops comprise molecules of catalyst or of catalyst covalently attached to a growing polymer chain, that are dissolved (preferably) or suspended in a solvent. (See, e.g. Figure ID.)

[0051] As used herein, a “catalyst-polyolefin macrochelate” is a molecule comprising a molecule of a cationic diimmine transition metal complex liganded with a polymerized olefin (e.g. polyethylene) and with a molecule of a polar monomer. See, for example, the Pd-PE- macrochelate shown in Figure 6.

[0052] One aspect of the present disclosure relates to a continuous flow reactor system for the synthesis of polyolefin-polar block copolymers comprising: a) a first tubular reactor having an inlet end and an outlet end, the inlet end in fluid communication with a source of olefin and a source of a catalyst;b) a first backpressure regulator valve having an inlet end and an outlet end, the inlet end in fluid communication with the outlet end of the first tubular reactor for controlling internal pressure of the first tubular reactor; c) a second tubular reactor having an inlet end and an outlet end, the inlet end in fluid communication with a source of an acrylate monomer and a first reaction product of the first tubular reactor; d) a source of blue light in optical communication with the second tubular reactor; e) a second backpressure regulator valve having an inlet end and an outlet end, the inlet end in fluid communication with the outlet end of the second tubular reactor for controlling internal pressure of the second tubular reactor; and f) a collection vessel for collecting a polyolefin-polar block copolymer product.

[0053] In such a reactor, the length of the tube is one parameter that can affect residence time of a reaction mix in the first reactor. In turn residence time influences the resulting length of the polymer block, with longer residence time generally resulting in higher molecular weight.

[0054] Referring to Figure 6, the inlet end of the first reactor 11 is configured to be operably connected to the outlet of the first T-connector 9 that in turn is configured to continuously receive a gas under pressure through a first inlet and a liquid pressurized by a pump through a second inlet, and to mix the two. The first inlet of the first T-connector is configured to be operably connected to a Mass Flow Controller (MFC) 3 that controls a flow of gas from a pressurized container 1. Similarly, the second inlet of the T-connector is configured to receive a liquid pumped by a first pump 7 through a line from a first reservoir 5 suitable for holding an organic solvent in which a catalyst is dissolved. The line from the reservoir to the T-connector might include a switching valve (not shown) that may be placed between the reservoir 5 and first pump 7) also configured to receive liquid pumped from a second reservoir (also not shown) for holding an organic solvent for flushing the system. The first pump can be set at a flow rate of, e.g. from 0.1 to 6 mL / min, preferably from 1 to 6 mL per minute or from 3 to 6 mL / min. By appropriately balancing the flows into the T-connector from its first and second inlets, gas and liquid reagents can be introduced into the first reactorin a stream of alternately droplets of the liquid phase and bubbles of the gas phase that flow through the tubular reactor (the “droplet flow”).

[0055] The outlet end of the first reactor is configured to operably connect to a first backpressure regulator 13. The backpressure setting affects the amount of the olefin reactant that dissolves in the liquid phase (higher pressure driving a higher concentration of olefin in the liquid phase). The flow rate of the droplets and intervening gas phase bubbles through the first reactor is controlled by the flow rate of the first pump 7.

[0056] In use of one embodiment, referring again to Figure 6, after flushing the system with an organic reaction solvent from a reservoir filled with the reaction solvent (not shown), which can be di chloromethane (DCM) or chlorobenzene (PhCl), connected to the system through the T-connector 9, olefin (e.g. ethylene or hexane) is delivered to the first reactor in gaseous form from a pressurized container 1 through a Mass Flow Controller (MFC) 3 to the T-connector 9. The MFC can provide the olefin gas at a pressure of from 75 to 750 psi (5 to 50 bar), preferably from 150 to 375 psi (10 to 25 bar). The first reactor is preferably tubular in shape and can be made from, e.g. fluorinated ethylene propylene (FEP). The first reactor can be made of metal, if a high process temperature or pressure is to be used.

[0057] A catalyst comprising a transition metal diamine complex, for example a (Pd+)diamine complex including an ancillary ligand, for example acetonitrile (e.g. Cl catalyst), in a solution of an organic solvent, for example dichloromethane (DCM) or chlorobenzene (PhCl), is drawn from a first reservoir 5 by a first pump 7 to the T-connector valve 9, where it is mixed with the olefin gas, forming bubbles of olefin in equilibrium with and separating droplets of the liquid solvent phase comprising the olefin and catalyst (the droplet flow) and, as the CIP reaction proceeds, molecules of polyolefin terminating in a catalyst complex. The droplet flow then flows into to the first reactor 11.

[0058] A first backpressure regulator (BPR) 13 is operably connected to the outlet of the first reactor to control the rate of the droplet flow through the first reactor. Typically, the first backpressure regulator is set to maintain the backpressure at a range of 1 to 450 psi, e.g. 15 to 375 psi (1 to 25 bar), preferably 150 to 300 psi (10 to 20 bar) in the first tubular reactor.Plainly, the backpressure should not exceed specifications of the reactor material or of any connecting lines or other parts of the system upstream of the first BPR.

[0059] A backpressure of about 250 psi (17 bar) is typical, and application of a modest backpressure aids in solubilizing the olefin monomer in the solvent phase and maintaining a consistent droplet flow.

[0060] Generally, the pressure of the MFC is set 30 to 150 psi (2 to 10 bar) above the backpressure set at the first BPR, to provide overpressure to drive the droplet flow through the system.

[0061] An optional tap 14 can be placed in line after the first backpressure regulator to allow drawing off aliquots of the droplet flow for analyzing the product of the insertion polymerization in the first reactor.

[0062] A first inlet of a second T-connector 19 is operably connected to the outlet of the first backpressure regulator (or to the line outlet of the optional tap). A solution of a polar monomer, for example, an acrylate monomer or a (meth)acrylate monomer, is drawn from a second reservoir 15 holding a solution of the polar monomer in an organic solvent, for example DCM or PhCl, by a second pump 17 and flows to a second inlet of the second T- connector 19. The line from the second reservoir to the second T-connector might include a switching valve (not shown) that may be placed between the second reservoir 15 and second pump 17 and also configured to receive liquid pumped from a second reservoir (also not shown) for holding an organic solvent for flushing the system. The droplet flow and the polar monomer solution mix in the second T-connector and the mixed droplet flow flows through the inlet of a second reactor 21. The concentration of the polar monomer can range from 0.01 to 20 mmol / ml, preferably from 0.1 to 10 mmol / ml or from 2 to 6 mmol / ml.

[0063] The second pump flow rate can be set at a flow rate of, e.g. from 0.1 to 2 mL / min, preferably from 0.1 to 1 mL per minute or from 0.2 to 0.5 mL / min. Typically the second pump flow rate will be set the same as the first pump flow rate.

[0064] The second reactor 21 is made from a transparent material that is able to efficiently pass light of blue to ultraviolet wavelengths, preferably wavelengths from 100 to 470 nm or from 300 to 470 nm or 440 to 470 nm. The second reactor is preferably made of a glass orfrom a transparent, solvent-resistant plastic such as FEP. As the droplet flow passes through the second reactor, it is exposed to light from a source of blue to ultraviolet light 23. The light source can be any continuous source known in the art, such as an arc lamp with an appropriate filter, or a LED. The light source should have sufficient output to evenly illuminate the entire volume of the second reactor.

[0065] The light source can be a plurality of point lights disposed around the second reactor. An OLED light source can be wrapped around the outside surface of the second reactor.

[0066] The light source can be one that emits light of wavelengths from 100 to 470 nm or from 300 to 470 nm or 440 to 470 nm. Preferably the light source is one that emits light of wavelengths from 450 to 460 nm. If the Cl catalyst is used to polymerize an acrylate or (meth)acrylate monomer it is preferable to use a light source emitting in the range from 450 to 460 nm.

[0067] The second reactor is preferably tubular in shape, as this will provide a more even exposure to the light throughout the volume of the reaction as the flow moves through the second reactor, providing a more controlled reaction. A more spherical reactor, for instance, suffers from less light penetration to the center of the reactor compared to the portion of the volume closer to the surface.

[0068] The length of the second reactor is such as to provide a suitable time of exposure to the light to allow a suitable degree of polymerization of of the polar monomer introduced into the reaction flow at the flow rate through the second reactor.

[0069] The outlet of the second reactor is operably connected to a second backpressure regulator 25. The second backpressure regulator can be set to maintain the backpressure at a range of 15 to 150 psi (1 to 10 bar), preferably 30 to 100 psi (1.5 to 7 bar) in the second tubular reactor. Generally, the pressure of the first BPR is set 1.5 to 10 times above the backpressure set at the second BPR, to provide overpressure to drive the droplet flow through the system.

[0070] The outlet of the second backpressure regulator is operably connected to a collection vessel 27 in which the final block copolymer product is collected. A quenchingcomposition, e.g. trimethyl silane liquid, can be provided in the collection vessel to terminate any ongoing reaction.

[0071] After collection, the block copolymer product can be concentrated by removal of the organic solvent (e.g. by evaporation and preferably recycling of the solvent) and then further processed or purified, e.g. by chromatographic separation of size fractions or the like.

[0072] A second aspect of the present disclosure is a polyolefin-polar block copolymer produced using the continuous flow reactor system disclosed herein. Such a polyolefin-polar block copolymer can be a diblock copolymer comprising a polyolefin block and a polar polymer block, (e.g. a polyethylene-polyacrylate or a polyethylene-poly(meth) acrylate diblock copolymer), or a triblock copolymer (e.g. a polyacrylate-polyethylene-polyacrylate or a poly(meth)acrylate-polyethylene-poly(meth)acrylate copolymer).

[0073] A third aspect of the present disclosure is a method of producing polyolefin-polar block copolymers comprising: a) combining olefin monomers in a gas phase with a catalyst in a liquid phase to produce a polyolefin-catalyst precursor; b) combining an acrylate monomer with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate; and c) exposing the catalyst polyolefin macrochelate in the presence of acrylate monomer to blue light to form a polyolefin-polar block copolymer.

[0074] The combining of the olefin monomers in the gas phase with the catalyst in the liquid phase can be done by equilibrating the gaseous monomer in contact with the liquid phase so that molecules of the monomer partition from the gas into the liquid phase. The equilibrating can occur while a bubble of the gas contacts a droplet of the solution of the catalyst in the droplet flow, or while the droplet flow is being formed by bubbling the olefin gas into the catalyst solution, e.g. at the first T-connector of the apparatus described above.

[0075] In methods disclosed herein, the olefin monomer can be any olefin monomer that is a gas at the process temperature, which can be from 5 to 50 °C, but is typically room temperature (i.e. from 20 to 25 °C).

[0076] Preferred olefins are ethylene, propylene and butadiene. Use of propylene and higher olefins may result in precipitation of the forming polymer from the liquid phase, and so use of a somewhat higher process temperature might be used in such an instance.Alternatively, if the polymer product is one that tends to crystallize or precipitate, then the feed rate of the monomer and catalyst can be reduced so that the concentration of the polymer product in the product stream is lower and any precipitate that forms does not clog the system.

[0077] The olefin monomer is preferably not diluted by any inert gas such as argon or nitrogen.

[0078] Increasing the amount of gaseous monomer in the reaction (e.g. by increasing the flow rate through the Mass Flow Controller or increasing the backpressure in the first reactor) will increase the yield and molecular weight of the polyolefin block. Increasing the catalyst concentration in the reaction step a) will decrease the molecular weight of the polyolefin block, as more chains will be initiated.

[0079] In some embodiments, the catalyst is a cationic late transition metal complex, for example, a cationic diimine Pd^ complex. Exemplary suitable catalysts are provided in FIGS. 1-3 of US Patent 11987652. FIG. 1 and FIG. 2 of the patent show cationic nickel and palladium catalysts with counterion (e.g., tetrakis[3,5-bis(trifluoromethyl)phenyl]-borate (BArF)). In embodiments, the catalyst comprises a cationic palladium catalyst as shown in la, lb, 1c, Id, 2a, 2b, 2c, 2d, 3a, 3b, 3c, 3d, 4a, 4b, 4c, and / or 4d of FIG. 1 of US Patent 11987652. In embodiments, the catalyst comprises a cationic nickel catalyst as shown in 5a, 5b, 5c, 5d, 6a, 6b, 6c, 6d, 7a, 7b, 7c, 7d, 8a, 8b, 8c, and / or 8d of FIG. 2 of US Patent 11987652. In embodiments, the polymerization catalyst comprises a nickel, iron, or cobalt catalyst selected from 9a, 10a, I la, or 12a, depicted in FIG. 3 of US Patent 11987652.Suitable anionic counterion (e.g., tetrakis[3,5-bis(trifluoromethyl)phenyl]-borate (BArF)) is shown at the top of FIG. 1 and FIG. 2 of US Patent 11987652.

[0080] Synthesis of the above catalysts is described in paragraphs

[0093] and following in US Patent 11987652.

[0081] Other catalysts and counterions are possible that can be activated by light to perform MILRad polymerization.

[0082] Solid catalyst is dissolved in an organic solvent, for example DCM or PhCl. The catalyst can be provided at a concentration of from 1.0 to 50 pmol / ml, preferably at a concentration of from 1.0 to 25 pmol / ml, or from 1.0 to 10 pmol / ml or from 1 to 5 pmol / ml or from 2 to 5 pmol / ml.

[0083] A double-headed MILRad catalyst such as 14a and 15a as described in US Patent 11987652 can be used to prepare a triblock copolymer, e.g. a polyacrylate-poly ethylenepolyacrylate triblock copolymer.

[0084] Preferably the same catalyst is used in the Coordination-Insertion polymerization of the olefin as is used in the Metal-organic Insertion Light-initiated Radical polymerization of the polar monomer.

[0085] Acrylate and (meth)acrylate monomers, for example methacrylate, ethyl acrylate, n-butyl acrylate or t-butyl acrylate, are preferred as polar monomers and are added as solutions in an organic solvent, such as DCM or PhCl. Increasing the concentration of the polar monomer will increase the molecular weight of the polar monomer block.

[0086] Polymerization of various polar monomers in the presence of various catalysts is described in Example 2 of US Patent 11987652. The conclusions from that experiment described at cols. 20-21 therein regarding preferential pairings of reactants and catalysts can be applied to the present invention.

[0087] The steps b) and c) are preferably performed at room temperature or thereabout.

[0088] A third aspect of the present disclosure is use of a continuous flow reactor system comprising a first tubular reactor configured to maintain a plurality of volumes comprising gas phases comprising an olefin monomer separated by interfacial contact with a liquid phase comprising a catalyst and any catalyst-polyolefin precursor product of contact of the olefin monomer with the catalyst, and a second reactor configured to maintain a plurality of volumes comprising gas phases comprising an olefin monomer separated by interfacial contact with a liquid phase comprising an acrylate monomer, the catalyst-polyolefin precursor and any product catalyst-polyolefin macrochelate, and further configured to expose a volume of the liquid phase to blue light, to produce a polyolefin-polar block copolymer. In an alternative, the second reactor can be configured to contain a liquid phase comprising an acrylatemonomer, the catalyst-polyolefin precursor and any product catalyst-polyolefin macrochelate, and further configured to expose a volume of the liquid phase to blue light, to produce a polyolefin-polar block copolymer.

[0089] The methods disclosed herein can be performed in a provided continuous flow reactor system capable of enabling a gas phase and a liquid phase in reactive communication.

[0090] A fourth aspect of the present disclosure is a block copolymer, which can be a diblock copolymer (e.g. a polyethylene-polyacrylate or a polyethylene-poly(meth) acrylate diblock copolymer), or a triblock copolymer (e.g. a polyacrylate-polyethylene-polyacrylate or a poly(meth)acrylate-polyethylene-poly(meth)acrylate copolymer) produced by the methods disclosed herein.

[0091] A fifth aspect of the present disclosure resides in use of a continuous flow reactor system comprising a first tubular reactor configured to maintain a plurality of volumes comprising gas phases comprising an olefin monomer separated by interfacial contact with a liquid phase comprising a catalyst and any catalyst-polyolefin precursor product of contact of the olefin monomer with the catalyst, and a second reactor configured to receive a plurality of volumes comprising gas phases comprising an olefin monomer separated by interfacial contact with a liquid phase comprising an acrylate monomer, the catalyst-polyolefin precursor and any product catalyst-polyolefin macrochelate, and further configured to expose a volume of the liquid phase to blue light, to produce a polyolefin-polar block copolymer. The second reactor can be configured to allow collapse of the separated bubbles to form a single liquid phase that moves by laminar flow (or nearly so) through the second reactor.

[0092] A sixth aspect of the present disclosure resides in a block copolymer produced by this use. Such a block copolymer can be a diblock copolymer (e.g. a polyethylene- polyacrylate or a polyethylene-poly(meth) acrylate diblock copolymer), or a triblock copolymer (e.g. a polyacrylate-polyethylene-polyacrylate or a poly(meth)acrylate- polyethylene-poly(meth)acrylate copolymer).

[0093] A seventh aspect of the present disclosure resides in use of a gaseous olefin monomer, a cationic diimine Pd^ complex in a liquid phase, and an acrylate monomer in a liquid phase to produce a polyolefin-polar block copolymer. Such a use can beone wherein a polyolefin block of the copolymer is formed by living Coordination- Insertion polymerization of the olefin monomer at an interface of the gas and liquid phases or that has partitioned into the liquid phase, and the polar block of the copolymer is formed by Metal-organic Insertion Light-initiated Radical polymerization of a Pd-polyethylene macrochelate.

[0094] An eighth aspect of the present disclosure resides in polyolefin-polar block copolymer produced by such uses. Such a polyolefin-polar block copolymer can be a diblock copolymer (e.g. a polyethylene-polyacrylate or a polyethylene-poly(meth) acrylate diblock copolymer), or a triblock copolymer (e.g. a polyacrylate-polyethylene-polyacrylate or a poly(meth)acrylate-polyethylene-poly(meth)acrylate copolymer).

[0095] A ninth aspect of the present disclosure is a method of producing polyolefin-polar block copolymers comprising: a) partitioning olefin monomers in a gas phase into a liquid phase comprising a catalyst and polymerizing the olefin monomers by a coordination-insertion polymerization to produce a polyolefin-catalyst precursor in the liquid phase; b) mixing an acrylate monomer in a liquid phase with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate in the liquid phase; and c) exposing the catalyst-polyolefin macrochelate in the presence of acrylate monomer to light to form a polyolefin-polar block copolymer by Metal-organic Insertion Light-initiated Radical polymerization .

[0096] A tenth aspect of the present disclosure resides in polyolefin-polar block copolymer produced by such methods. Such a polyolefin-polar block copolymer can be a diblock copolymer (e.g. a polyethylene-polyacrylate or a polyethylene-poly(meth) acrylate diblock copolymer), or a triblock copolymer (e.g. a polyacrylate-polyethylene-polyacrylate or a poly(meth)acrylate-polyethylene-poly(meth)acrylate copolymer).

[0097] The block copolymers prepared as described herein can be concentrated and isolated and purified from the polymerization reactions by methods known in the art, for example, by evaporation of the solvent, redissolving the polymer in a solvent and gel permeation chromatography of the concentrated polymer.EXAMPLES

[0098] General considerations

[0099] All manipulations of palladium complexes were carried out under an inert atmosphere (N2) using a glove box, glove bag, or standard Schlenk techniques unless otherwise noted. All glassware was flame-dried under a vacuum before use.

[0100] Materials

[0101] Calcium hydride powder (Cal > 90%), diethyl ether anhydrous (> 99 %), and acetonitrile ACS reagent (>99 %) 2,3 -butanedione (97%) were purchased from Sigma-Aldrich and used as received. 2,6- diisopropylaniline (90%) was purchased from Oakwood Chemical, formic acid (98-100%) was purchased from Millipore Sigma, and both were used as received. Chloromethyl(l,5-cyclooctadiene) palladium (II) (99%) was purchased from Stream Chemicals Inc. and used as received. Sodium tetrakis[3,5- is(trifluoromethyl)phenyl]-borate (NaBAr'4, 97%) was purchased from Matrix Scientific and used as received. Chlorobenzene (anhydrous, >99.8%) was purchased from Sigma-Aldrich and degassed by three freeze-pump- thaw cycles under nitrogen gas immediately before use. HPLC grade methanol (99%), methylene chloride (DCM, 99 %), diethyl ether (99%), pentane (99.5%), and hexane (99%) were purchased from Fischer Scientific. Methylene chloride, ethyl ether, and pentane were dried and degassed by passage through columns containing oxygen scavenger copper (0) and 4 A molecular sieves under an argon atmosphere. Methanol was used as received without further purification. Ethylene (polymer grade) was purchased from Matheson Tri Gas and used as received. Methyl acrylate (MA, 99%), ethyl acrylate (EA, 99%), / / -butyl acrylate (n-BuA, 99%), tert-butyl acrylate (t-BuA, 98%) were purchased from Sigma Aldrich and distilled over CaH , then degassed by three freeze-pump-thaw cycles under nitrogen gas immediately before use.

[0102] Instrumentation

[0103] Nuclear Magnetic Resonance (NMR):JH spectra were performed at room temperature on a JOEL JNM-ECA 400 (400 MHz) and ECA-600 (600 MHz). Chemical shifts for!H were measured relative to residual solvent peaks as an internal standard set to 5 7.26 (Chloroform- / / ; (CDCI3)) and 8 6.00 (l,l,2,2-tetrachloroethane-d2 (TCE-t / ?)). Diffusion-ordered NMR spectroscopy (DOSY) of block copolymers was performed on the ECA-600. The parameters of the experiments for the diffusion time were set to 0.4 s, delta = 4 ms, and relaxation delay = 7 s. An exponential array function was applied between 3 mT / m and 300 mT / m for points =16 with 8 scans.

[0104] Gel Permeation Chromatography (GPC): All homopolymers of polyethylene and poly(m ethyl acrylate), and the block copolymers were analyzed using a Tosoh high- performance GPC system HLC-8320 equipped with an auto-injector, a built-in dual differential refractive index (RI) detector, and TSKgel G series columns connected in series (7.8 x 300 mm TSKgel G5000Hxl, TSKgel G4000Hxl, TSKgel G3000Hxl). HPLC grade tetrahydrofuran (THF) was used for the GPC analyses carried out with a flow rate of 1 mL / min at 40 °C. Number average molecular weights (Mn), weight average molecular weight (Mw), and molecular weight distributions (D) were calculated from polystyrene (PS) standards with molecular weights of 800 to 2.2 x 106g mol'1provided by Polymer Standard Service (PSS).

[0105] Small Angle X-Ray Scattering (SAXS): A Xenocs Ganesha small angle scattering instrument fitted with a movable Dectris 300k detector was used to record extremely small angle scattering data. The instrument is fitted with a microfocus Cu k-alpha source operated at 50kV and 0.6mA. Data were corrected to give absolute intensities using sample thickness and by measuring Iodirectly on the Dectris detector. A manufacturer-supplied utility, SAXS was used to make the corrections and reduce the 2D detector data into intensity vs. scattering angle data. The two-dimensional scattering patterns were azimuthally integrated into a onedimensional profile of intensity vs scattering vector, q = 4JE(0 / 2) / X. (0 is the scattering angle; X is the wavelength).

[0106] Differential Scanning Calorimetry (DSC): The glass transition temperatures (Tg) of prepared polymer samples were measured using a TA-DSC 2500, operated from -90 °C to 150 °C. The heating and cooling rates were set to 10 °C / min and 5 °C / min, respectively. All polymer samples were subjected to a heat-cool -heat cycle under a nitrogen atmosphere. The reported DSC data were obtained from the second heating cycle.

[0107] Mass Flow Controller (MFC): Ethylene gas was injected into the tubular reactor using a ThalesNano Gas Module (Model: 1.4.2). For a seamless gas flow, the pressure of the Gas Module was set 5 bar higher than the backpressure used for the reaction. To reach a steady state, the Gas Module ran for 3 retention times before the reaction started. The ethylene gas flow rates for the reactions are mentioned in the tables.

[0108] Flow Pump: KNAUER HPLC pumps (AZURA P4.1 S) were employed to inj ect the catalyst and monomer solutions into the tubular reactors. At first, the chlorobenzene (PhCl) without the reaction solutions ran for 3 retention times to achieve a steady state before the reaction started. Then, the pump inlets were switched to the reaction solutions, and after depleting the desired amounts of solutions, the inlets were again swapped to the solvent flask. After the completion of a reaction, the whole reactor was flushed with PhCl for 3 retention times.

[0109] BackPressure Regulator (BPR): Zaiput BPR-10 back pressure regulator from Zaiput Flow Technology was used to maintain a specified upstream pressure for ethylene polymerization at 100 psi and 250 psi. On the other hand, IDEX P-785 and P-791 (from IDEX Health & Science) back pressure regulators of 40 psi and 20 psi, respectively, were utilized for radical polymerizations of acrylates.

[0110] The light source for photopolymerization: Radical reactions for acrylate polymerizations were performed in the PhotoCube™ from ThalesNano under blue light of -457 nm wavelength provided at 84 Watts. The coil of the tubular reactor was placed in the light chamber of the PhotoCube™.

[0111] Other flow instruments: Tubing (FEP, 1 / 16" x 1.0 mm ID) for microreactor was purchased from VICI AG International. PEEK super flangeless nut (1 / 16", LT-115X and P- 255X), flangeless ferrule with SS ring (1 / 4-28 flat bottom, 1 / 16" OD, P-259X), low-pressure Tee assembly (1 / 4-28 flat bottom, 1 / 16" OD, P-712), inline check valve for inlets (3 psi, 1 / 4- 28 flat bottom, 0.02" ID, CV-3315), SS tubing (1 / 16" OD x 0.040" ID, U-144) were purchased for IDEX Health & Science.

[0112] Synthesis of ligands and complexes

[0113] Synthesi s of Bi s(2, 6-diisopropylaniline)-butane-2, 3 -diimineThe diamine ligand was prepared according to the literature precedents71,72A 250 mL round bottom flask was flame-dried and charged with 100 mL of methanol, 16.7 mL of 2,6- diisopropylaniline (15.71 g, 88.62 mmol, 2.1 eq.), and 3.7 mL of butanedione (3.63 g, 42.2 mmol, 1.00 eq.). Then, -200 pL of formic acid (4.0 mmol, 0.05 eq) was added to the solution and refluxed at 95 °C overnight. The reaction mixture was then cooled to room temperature, concentrated under reduced pressure, and cooled to -20 °C overnight. The solid residue was collected by vacuum filtration and washed with cold MeOH. The obtained yellow crystals were then dried in vacuo overnight.

[0115] 1H NMR (400 MHz, CD2C12, ppm) 8 7.18 (m, 4H), 7.10 (m, 2H), 2.73 (s, J = 6.60Hz, 4H), 2.07 (s, 6H), 1.22 (d, J = 5.93 Hz, 6H), 1.20 (d, J = 5.93 Hz, 6H), 1.18 (d, J = 5.93 Hz, 6H), 1.16 (d, J = 5.93, 6H).

[0116] Synthesis of (Ar-N=C(Me)-C(Me) =N-Ar)Pd(Me)( Cl) (Ar = 2, 6- diisopropylaniline) ; Cl precursorThe compound was synthesized following a modified literature procedure.71,72A flame-dried round bottom flask was charged with chloro (1,5-cyclooctadiene) methyl palladium (II) (270 mg, 1.02 mmol, 1 eq.) and a slight excess of bis(2,6-diisopropylaniline)-butane-2,3-diimine (450 mg, 1.11 mmol, 1.09 eq.). 10 mL of diethyl ether was then added to the mixture, covered with aluminum foil, and stirred overnight. Excess ligands and diethyl ether were removed in vacuo. The product was washed twice with 10-20 mL of cold diethyl ether and dried in vacuo overnight to obtain a yellow-orange solid (yield -91%).

[0118] 'H NMR (400 MHz, CD2CI2, ppm): 5 7.36 - 7.20 (m, 6H), 3.08 (sep, J = 6.60 Hz, 2H), 3.02 (sep, J = 6.93 Hz, 2H), 2.03 (s, 3H), 2.02 (s, 3H), 1.40 (d, J = 7.31 Hz, 6H), 1.35 (d, J = 7.31 Hz, 6H), 1.18 (d, J = 6.99 Hz, 6H), 1.16 (d, J = 6.99 Hz, 6H), 0.36 (s, 3H).

[0119] Synthesis of [(Ar-N=C(Me)-C(Me)=N-Ar)Pd(Me)(CH3CN) ]+ [B(3,5-CaHsfCF^]; Cl catalystThe catalyst was synthesized following a modified literature procedure71,72In a flamed dried round bottom flask, sodium tetrakis[(3,5-bis(trifluoromethyl)phenyl)]borate (NaBArF) (250 mg, 0.282 mmol, 1.05 eq.) and Cl precursor (Ar-N=C(Me)-C(Me)=N-Ar)Pd(Me)(Cl) (150 mg, 0.267 mmol, 1.00 eq.) was added followed by the addition of 5 mL of acetonitrile. The reaction mixture was covered with aluminum foil and stirred overnight. The resulting solution was filtered to remove NaCl, and excess acetonitrile was removed by evaporation. The solid was redissolved in a minimum amount of DCM and washed and precipitated in pentane. The precipitate was collected by vacuum filtration and dried in vacuo.

[0121] ' H NMR (400 MHz, CD2CI2, ppm): 8 7.72 (m, 8H), 7.56 (m, 4H), 7.41 - 7.32 (m,6H), 2.89 (sep, J = 6.93 Hz, 2H), 2,85 (sep, J = 6.93 Hz, 2H), 2.22 (s, 6H), 1.79 (s, 3H), 1.37 (d, J = 6.94 Hz, 6H), 1.32 (d, J = 6.94 Hz, 6H), 1.24 (d, J = 6.94 Hz, 6H), 1.20 (d, J = 6.94 Hz, 6H), 0.50 (3, 3H).

[0122] Calculations

[0123] Branching number of polymer and monomer incorporation were calculated via1HNMR.76Branching (perwhere CH3 is the integral of CH3 (0.75-0.95 ppm); CH2+CH is the integral of CH2 & CH (1.10-1.50 ppm).4(0Me)The MA incorporation (mol%) = — - - — - x 100%1 v’ 4(OMe)+2(CH3)+3(CH2+CH)where OMe = Integral of OMe group from PMA (3.67-3.82 ppm); CH3 = Integral of CH3 from PE (0.75-0.95 ppm); CH2+CH = Integral of CH2& CH from PE (1.10-1.45 ppm).The EA incorporation (mol%) = - 12(OCH2) - X 100%1 v’ 3(OCH2)+6(CH2+CH+CH3OEt)+4(CH3) where OCH2 = Integral of OCH2group from PEA (4.12-4.25 ppm); CH3 = Integral of CH3from PE (0.85-0.98 ppm); CH2+CH+CH3OEt = Integral of CH2& CH from PE and CH3from PEA (1.10- 1.50 ppm).The n-BuA incorporation (where OC7 / 2 / / Pr = Integral of OCH2on OBu group from P( / / -BuA) (4.05-4.25 ppm); CH3 =Integral of CH3 from PE & P( / / -BuA) (0.85-1.08 ppm); CH2+CH = Integral of CH2& CH from PE& P(n-BuA) (1.15-1.55 ppm).12(CH2CHCOOtBu)The / -BuA incorporation (mol%) = X 100%3(CH2+CH+CH3tBu)+2(CH3) -5(CH2CHCOOtBu) where CH2CffCOOtBu = Integral of CH2CHCOO / Bu from P(ABuA) (2.28-2.42 ppm); CH3 = Integral of CH3from PE (0.85-0.98 ppm); CH2+CH+CH3tBu = Integral of CH2& CH from PE and CH3from P(ABuA) (1.11-1.59 ppm).

[0124] Synthesis of polyethylene homopolymer in continuous flow

[0125] Table 1 summarizes the influence of the flow parameters on the molecular weight and yield of the synthesized polyethylene. In the experiments, the lengths of the reactor and pump flow rates were chosen so as to synthesize a polymer of “standard” molecular weights (5 to 15 kg / mol).

[0126] Referring to Table 1 below, in the CIP of ethylene, a gas-liquid heterogeneous system was utilized in the form of droplet flow consisting of catalyst solvent droplets separated by the ethylene monomer gas phase (Figure ID, Figure 2B). This study investigated the effects of various flow parameters such as residence time, monomer concentration, and catalyst concentration in detail for optimization of PE homopolymer synthesis, summarized in Table 1. It was found that the residence time of the reaction has a significant impact on the average molecular weight (Mn) and the yield of PE homopolymers. Residence time in flow chemistry refers to the time a reagent or reactant spends inside a flow reactor during a chemical reaction. The residence time can be regulated by adjusting the flow rate of feed solutions or the length of the reactor. In the initial setup, testing suitable residence times in the flow, it was attempted to match the same reaction times of CIP in the flow with a batch reaction using similar reaction procedures (see, e.g. US Patent 11987652) so that we could compare in the two modes of reaction. We found that the Mnof the batch reactions are similar to the reactions that were run in the flow at the same residence times when we targeted Mnranging from 5-40 kg / mol.

[0127] Increasing the flow rate of the Cl catalyst solution from 0.15 mL / min to 0.30 mL / min reduced the residence time to -50% (entry 1 & 2), which led to a decrease in molecular weight (14.28 to 5.68 kg / mol) of the product almost in the same ratio. Conversely, these outcomes were enhanced (roughly double) with an increase in residence time ~4 min to ~6 min resulting from increasing the reactor length from 1.5 m to 3.0 m (entry 2 & 3). Since the greater residence time offers an extended duration of reaction, it ensures a longer span for chain propagation to obtain higher Mn and yield.Table 1. Insertion polymerization of ethylene in the presence of Cl catalyst in a continuous flow reactor"Length Cone, of Gas flow rateof Pump Res. Cl cat. in BPR Mn £> Yield TOFEntry reactor flow rate time PhCl(m) (mL / min) (min) (pmol / mL) (mL / min) (psi) (kg / mol) (mg) (h-1) branches / 1000 cd1 1.5 0.152.106 25014.28 1.06 75 2429.54 1032 1.5 0.30 4 2.10 6 250 5.68 1.07 87 2465.98 1063 3.0 0.302.106 2501 1.63 1.04 128 2418.74 1074 3.0 0.30 6 1.40 6 250 13.74 1.05 1 13 3202.94 1095 3 0 0.301.406 10013.45 1 05 109 3089.57 1066 3.0 0.30 7 1.40 3 100 9.03 1.04 70 1700.68 107 / 30 min reaction time.^Ethylene gas flow was controlled by a mass flow controller. cMolecular weight (Mn) and poly dispersity index (D) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards.(^Determined by1H-NMR in CDCL at 25 °C. e60 min reaction time.

[0128] Interestingly, CIP of ethylene with higher catalyst concentration resulted in PE chains of lower Mn (entries 3 & 4). An excess of catalyst led to a faster initiation and propagation of monomer units, which increased the polymer yield. Nevertheless, this extended initiation consequently created an event of multiple competing polymerizations, where the individual polymer chains received fewer monomer units and had less time to grow before they were quenched. This shorter chain growth resulted in shorter polymer chains with lower average molecular weight. On the contrary, an increase of ethylene gas injection with similar residence time ensures an additional extent of monomer units in the reaction,corresponding to extended propagation and chain growth leading to enhancement oiMn and yield of PE, and was observed in the cases of entries 5 & 6.

[0129] The Cl complex was exploited to perform the CIP of ethylene in four major steps: initiation, chain propagation, metal migration through the polymer chain (chain walking), and chain transfer (Figure 8). The insertion pathway initiates through the coordination of the Cl complex with ethylene monomer, and further successive coordination and insertion of ethylene forms the PE chain. The chain walking characteristic of the Pdll complex results in an agostic intermediate II, which can proceed to further coordination insertion with monomers to yield the stable it- complex III or can undergo |3-hy dride elimination to form IV. These Pdll ethylene TI- complexes (III & VI) are the resting state of this pathway, indicating that the insertion step is the rate-limiting step. Therefore, the rate of polymerization and the degree of branching are independent of system pressure.62'64As a result, changing the backpressure regulator in the flow system did not largely impact the production of PE homopolymer except for a subtle increase in Mn and yield (entry 4 & 5). Finally, continuing the reaction for a longer time from 30 min to 60 min without alternating any other parameters (entries 6 & 7) produced a homopolymer of similar Mn ~ 9.03 kg / mol and £> ~ 1.04 with a higher yield (around twofold) as it had utilized double the amount of feed solutions, which is an appropriate illustration of the easy scalability of production in this method.

[0130] A further kinetic study of PE chain extension based on the residence time varying the flow rate of the reactants was performed to investigate the living window of PE homopolymerization. The continuous flow reactor for polyethylene homopolymerization was set up as shown in Figure 2B, and the details of the parameters of this further study are given in Table 2.

[0131] A flame-dried round bottom flask charged with fresh chlorobenzene (PhCl) was used as the solvent for the reaction and kept in a nitrogen-filled glove bag. In the beginning, this PhCl was pumped for 3 retention times through the flow reactor via an HPLC pump. Ethylene gas was then injected into the reactor using a mass flow controller (MFC). For a seamless gas flow, the pressure of the MFC was always set at 6 bar (~87 psi) higher than the backpressure employed for the reaction, and to reach a steady state, the gas was run for 3retention times before the reaction started. A 50 mL flame-dried pear-shaped flask was charged with Cl catalyst solution prepared in PhCl of the desired concentration in the glove bag. Then, the pump inlet was switched to the catalyst solution. Since it is a gas-liquid biphasic system, the residence time of the reactant solutions traveling as droplet flow in the flow reactor was determined by visual observation.73After depleting the desired volume of solution in the reactor, the inlet was again swapped to the solvent flask. The product was collected from the reactor outlet in another round bottom flask containing triethyl silane to quench any further reaction. The solvent was then removed via a rotatory evaporator. The obtained residue was washed with methanol, dissolved in hexane, filtered through a plug of silica, and concentrated. The isolated polymer was then dried in vacuo and analyzed by NMR, GPC, and DSC (presented in Table 2 below)."Reaction conditions: 2.10 pmol / mL concentration of Cl catalyst, 3 m of reactor length, 6 mL / min ethylene gas flow rate, 250 psi of back pressure regulator, 30 minutes reaction time. ^Residence time was determined by the visual measurement. "Molecular weight (Mn) and poly dispersity index (D) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards. ^Determined by1H-NMR (400 MHz, CDCh, 25 °C).

[0132] The kinetic study establishes the living character of the coordination insertion polymerization in continuous flow. In Figure 3B, a linear agreement following first- order kinetics between the increase in average molecular weight (Mn) from 5.88 kg / mol to 42.19 kg / mol with the increase of resident time from 3 min to 21 min maintaining a narrow polydispersity, D = Mw / Mn ~ 1.05 was observed. This relation evidenced the subsequent monomer propagation for continuing the PE chain growth within a living time frame over the P-hydride elimination to occur the chain transfer.60,65 66In the case of living polymerization, after the fast chain initiation, a constant rate of chain propagation is maintained in the absence of chain termination. As a result, a linear relationship between the molecular weight of the polymers, and reaction time with narrow dispersity is observed. Therefore, PE polymerization in the flow reactor is a living process, and one can aim for any desired length of PE segment by varying the residence time.

[0133] Although in these experiments were designed to produce a range of molecular weight from 5 to 42 kg / mol, the first-order kinetics ensure that it is possible to synthesize pol ethylene chains of lower than 5 kg / mol or over 100 kg / mol by modulating the flow rate and first reactor length.

[0134] Comparison of PE homopolymerization in batch vs. flow reactor

[0135] Synthesis of PE in batch: A 300 mL Parr® reactor was equipped with a mechanical stirrer, heating mantle, and thermocouple. The reactor was heated overnight to 90 °C under vacuum and then vented with argon gas before being cooled to room temperature. The reactor was pressurized with ethylene gas to 100 psi and vented thrice. 30 mL of chlorobenzene was then added to the reactor through the sampling port, and the system was stirred until it equilibrated at 25 °C. 150 mg of Cl catalyst was dissolved in 20 mL of chlorobenzene andadded to the reactor through the sampling port, and the reactor was recharged with ethylene gas to 250 psi. After the allotted polymerization time of 6 min, the reaction was quenched with 500 pL of triethyl silane and transferred to a tared round bottom flask. The solvent was then removed via rotary evaporation. The residue was dissolved in hexane, filtered through a silica plug, and concentrated. The obtained polymer was then dried in vacuo and analyzed by NMR and GPC, and the data is reported in Table 3.Table 3. Comparison of PE homopolymerization between batch and flow reactor"Reaction / residence Cone, ofMn6Productivity TOFSample time Cat. D6(kg / mol) (kgmol^h-1) (h-1)(min) (pmol / mL) batch 9.95 1.01 71.62 2557.826 2.1 flow 11.63 1.04 67.72 2418.74"Reaction conditions: Cl catalyst was utilized for the reaction at room temperature, 3 m of reactor length, 6 mL / min of ethylene gas flow rate, 250 psi of back pressure regulator, and 30 minutes reaction time for the flow reaction. ^Molecular weight (Mn) and poly dispersity index (D) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards.

[0136] Although the experimental setups of the continuous flow reactor and batch process are entirely different, we examined if the experimental conditions impact the characteristics of the homopolymer when choosing the same catalyst concentration and reaction time. The resulting PE homopolymers, conducted in the batch and the flow, are summarized in Table 3 and Figure 11. In both processes, the obtained products were similar in characteristics such as Mn, D, and TOF. Therefore, we can conclude that the experimental conditions do not alter the polymerization results. However, in the case of batch reactions, every reaction vessel has a limited scale for its reaction volume. It limits an alteration in this scale (increasing or decreasing the reaction volume). So, the flow system is as well-capable of synthesizing a desired product as a batch reaction while offering the advantage of easier scalability and better control of the preparation.[00137J Radical polymerization in continuous flow

[0138] Synthesis of polyfmethyl acrylate) (PMA) homopolymer in continuous flow

[0139] The continuous flow reactor for poly(methyl acrylate) homopolymerization was arranged as shown in Figure 4B, and the details of the parameters are given in Table 4. A flame-dried round bottom was charged with fresh chlorobenzene (PhCl) to use as the solvent for the reaction and was kept in a nitrogen-filled glove bag. Before the reaction started, PhCl was pumped for 3 retention times through the flow reactor (a FEP tube) via two HPLC pumps to reach a steady state. A 50 mL pear-shaped flask was flame-dried and charged with Cl catalyst solution prepared in PhCl of the desired concentration in the glove bag. Another flame-dried 50 mL pear-shaped flask was charged with an MA solution of fixed concentration in PhCl and kept in the same glove bag. Then, the pump inlets were switched to the catalyst and MA solutions separately. After admitting the desired volume of each of the solutions into the reactor, the inlets were again swapped to the solvent flask to flush the reactor and collect the product. The reactor tube is illuminated by blue light (457 nm, 84 W) continuously during the reactor filling and subsequent product collection. The product was collected from the reactor outlet in another round bottom flask containing tri ethyl silane to quench any further reaction. The solvent was then removed via a rotatory evaporator. The obtained residue was redissolved in DCM, filtered through a PTFE filter, and precipitated in MeOH to yield a purified product. The isolated polymer was then dried in vacuo and analyzed by NMR, GPC, and DSC (Table 4).Table 4. Kinetic data of radical polymerization of methyl acrylate"Vol. ofPMAPump eachRes. - Product.(1& 2) solution Yield TOFEntry time , (kgmok flow rate (Cat. & MnJ, (mg) (h-1)(min) D ’(mL / min) MA) (kg / mol)(mL)1 0.05 40.00 1.5 80.06 1.92 148 70.48 818.632 0.07 26.67 2.0 76.81 1.94 195 114.82 1333.733 0.15 13.33 4.5 76.09 1.93 494 235.30 2733.154 0.30 6.67 9.0 47.57 1.92 535 254.63 2957.775 0.60 3.33 18.0 35.66 1.95 685 256.92 2984.36"Reaction conditions: 2.10 pmol / mL concentration of Cl catalyst, 5 m of reactor length, 40 psi of back pressure regulator, 30 minutes reaction time. ^Molecular weight (Mn) and poly dispersity index (D) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards.

[0140] Poly(methyl acrylate) (PMA) homopolymers were prepared through a light- initiated radical (LRad) pathway employing the same Pdll diamine Cl catalyst. The previously reported mechanistic study illustrated that the initiation of the reaction involves a 2,1 insertion of MA (excess) displacing the ancillary ligand acetonitrile (MeCN) from the catalyst to yield a four-membered intermediate, which is subsequently rearranged to form a stable six-membered chelate via chain walking. The presence of Lewis base (MeCN) aids the reopening of the chelate and Pd chain walk to the a-carbon, which is subsequently subjected to blue light (-457 nm) irradiation to undergo the Pd-C bond homolysis to generate the radical species for further FRP of MA67'69(Figure 12).

[0141] Like the CIP of ethylene, a similar investigation was conducted for the MILRad reactions of MA by varying the parameters of the flow system, and the obtained findings were mostly in similar alignments with CIP (Figure 4C & Table 5). The residence time is theactual duration of the synthetic transformation of the reactants to the product. Therefore, increasing the residence time by changing the flow rate of the monomer and the catalyst solutions (entry 1 & 2) or the length of the reactor (entry 2 & 3) offered an extended period for chain propagation and enhanced the Mn and yield of obtained PMA. On the other hand, elevated catalyst concentration from 1.4 pmol / mL to 2.1 pmol / mL resulted in a lowering of Mn (from 118.86 kg / mol to 72.02 kg / mol) of the prepared polymer as it originated a higher concentration of initiator radical species to initiate a greater number of polymer chains at the same time (entry 3 & 4) and termination increases as well as part of steady-state free radical kinetic behavior.58However, increased monomer concentration benefits a higher monomer propagation to form a longer chain with higher molecular weight (entry 3 & 5). In the end, a comparison between entry 5 & 6 elucidates that only the extended reaction time (30 min to 60 min) utilizing a higher amount of feed solution without varying any other flow parameters can generate a higher amount of PMA homopolymers (0.49 g to 1.03 g) of similar Mn (-38 kg / mol) and D (-1.94).

[0142] Although the range of molecular weights of the poly(methyl acrylate) shown in Table 5 is from 35 to 118 kg / mol, polymers of higher or lower molecular weight can be synthesized by modulating the reaction parameters.Table 5. Radical polymerization of methyl acrylate in the presence of Cl catalyst in a continuous flow reactor^Reaction conditions: 30 minutes reaction time, back pressure regulator = 40 psi. ^Molecular weight (Mn) and poly dispersity index (£>) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards. c60 minute reaction time.

[0143] The kinetic study of free radical polymerization of MA was also conducted based on the residence time by varying the flow rate in the same tubular reactor, as summarized in Figure 5 and Table 5. It can be seen from entry 1-3 that the molecular weight was initially increased up to ~76 kg / mol with the elevation of residence time resulting from lowering the flow rate. However, after reaching a maximum limit of Mn ~ 76 kg / mol, it became irresponsive to the elevation of residence time due to the characteristic kinetic behavior of a steady-state FRP in which chain terminations occur through disproportionation after acquiring a specific chain length.

[0144] Comparison of PMA homopolymerization in batch vs. flow reactor

[0145] Preparation of PMA homopolymer in batch: To a flamed dried 25 mL round bottom flask equipped with a stir bar, was added the catalyst Cl (27 mg, 18.90 pmol, 1 eq) in a glovebox. The flask was sealed with a septum, brought out of the glovebox, and wrapped with aluminum foil to prevent photodegradation of the catalyst. The wrapped flask was brought inside a glove bag filled with nitrogen and charged with 9 mL of PhCl. In another flame-dried 25 mL round bottom flask, 4.5 mL of MA solution (4.5 mL, 4.32 g, 50.18 mmol, 2655 eq) was added into 4.5 mL PhCl and then transferred in 2a solution. The reaction mixture was transferred to the PhotoCube™ instantly under blue light (-457 nm), and the reaction was run for 6.5 minutes with vigorous stirring. After the allotted time, the reaction vessel was removed from the PhotoCube™, and 500 pL of triethyl silane was added to quench any further reaction. The solvent was then removed via a rotatory evaporator. The obtained residue was redissolved in DCM, filtered through a PTFE filter, and precipitated in MeOH to yield a purified product. The isolated polymer was then dried in vacuo and analyzed by NMR, GPC, and DSC (presented in Table 6).Table 6. Comparison of PMA homopolymerization between batch and flow reactor"Reaction Cone, of MolMn YieldSample time Cat. eq. of D(kg / mol) (mg)(min) (pmol / mL) Cat. batch 49.45 1.94 5986.67 2.1 2655 flow 47.44 1.91 535"Reaction conditions: Cl catalyst was utilized for the reaction at room temperature, 5 m of reactor length, 6 mL / min of ethylene gas flow rate, 40 psi of back pressure regulator, and 30 minutes reaction time for the flow reaction. ^Molecular weight (Mn) and poly dispersity index (D) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards.

[0146] A PMA homopolymer was prepared in a batch reaction under similar reaction conditions for the same ~7 min reaction time (residence time for flow reactor) to illustrate a comparison with the product from a continuous flow process (Table 6). It was observed that there is a good agreement in the characteristics (Mn and £>) between both products (Figure 15), which signifies that the experimental setup of this continuous flow reactor is suitable for the MILRad reaction for these types of polar monomers.

[0147] Mechanism of polyethylene-polyacrylate block copolymer synthesis

[0148] Identity of macro-initiating radical species (radical trapping experiment)

[0149] After completing the study on PE and PMA homopolymerizations, we aimed to combine these two flow systems to synthesize polyethylene-polyacrylate block copolymers (PE- / 1-PMA). Herein, PE prepared through CIP is utilized as the precursor for further reaction progression to form the second block through FRP of acylate monomers (Figure 16).Therefore, we connected the continuous flow setups so that PE would form in the first reactor and then feed into the second reactor to react with MA, forming the Pd-PE-MA macrochelate. The presence of MeCN will facilitate the reopening of the macrochelate, which will consequently generate the PE-macroradical through Pd-C bond cleavage under blue light irradiation. This macroradical will then initiate the FRP in the presence of excess MA to form the BCPs. Initially, we worked with identical reaction conditions for the two reactors (entry 3 of Table 1 and entry 2 of Table 2), where both reactions were performed at the same flow rate (0.30 mL / min) with the same volume and concentration of catalyst solution (9.0 mL and 2.1 pmol / mL) respectively.

[0150] The flow reactor for the TEMPO trapping experiment was arranged as shown in Figure 17. A flame-dried round bottom flask was charged with fresh chlorobenzene (PhCl) to use as the solvent for the reaction and kept in a nitrogen-filled glove bag. PhCl was pumped for 3 retention times through the flow reactor via two HPLC pumps. Ethylene gas was then injected into the reactor using a mass flow controller (MFC). For a seamless gas flow, the pressure of the MFC was set at 23 bar, and to reach a steady state, ethylene gas was runthrough the MFC for 3 retention times before the reaction started. A 50 mL pear-shaped flask was flame-dried and charged with 16 mL of Cl catalyst solution (2.1 pmol / mL, 48 mg, 34 pmol, 1 eq.) prepared in PhCl and kept in the glove bag. An 8mL of MA solution (7.65 g, 88.84 mmol, 2644 eq.) and 52.50 mg of TEMPO (0.34 mmol, 10 eq.) were added into 8 mL of PhCl in another flame-dried 50 mL pear-shaped flask and kept in the same glove bag. Then, the pump inlets were switched to the catalyst and MA solutions separately, and after injecting the solutions for 30 minutes in the reactor, the inlets were again swapped to the PhCl flask to flush the reactor and collect the product. The second reactor was illuminated by blue light at 457 nm (84 W) during the entire process. The product was collected from the reactor outlet in another round bottom flask containing tri ethyl silane to quench any further reaction. The solvent was then removed via a rotatory evaporator. The residue was redissolved in hexane, filtered through a PTFE filter, and precipitated in MeOH to yield a purified product. The obtained TEMPO trapped product was then dried in vacuo and analyzed by NMR, GPC, and DSC (Table 7).

[0151] % composition of chain transfer product was calculated viarH NMR. chain transfer product (in %) = -- -7-x100%; here, f is the integral of internal CH=CH, h is the . J integral of terminal =CH2, a is the integral of TEMPO functionalized a-CH, e is the integral of a-CH.Table 7. Radical trapping experiment in continuous flow reactor in the presence of TEMPOCone, of Cone, of mol PE-MA-TEMPO mol % %Cl cat. in MA in equiv. of eq. of MA MnaFunc. chainPhCl PhCl TEMPO Dflto Cl (kg / mol) product6transfer6(pmol / mL) (mmol / mL) (mol)2.1 5.58 2655 10 12.64 1.05 84 16"Molecular weight (Mn) and poly dispersity index (D) were determined by gel permeation chromatography (GPC) analysis with samples ran in THF at 40 °C calibrated to polystyrene standards. ^Determined by 'H NMR spectrum (400 MHz, CDCI3, 25 °C).

[0152] However, to establish the formation of a macroradical, which is the transition step from CIP to FRP, a TEMPO trapping experiment (Figure 17) was performed to capture the alkyl radical species formed in the light cycle. In contrast to comparable experiments in bulk, in which the macrochelate was isolated from the reaction mixture and the TEMPO solution was added subsequently, TEMPO of the same extent (10 mol eq. with respect to the catalyst) was simply added to MA solution. The 1H-NMR analysis of the obtained product indicated that 84% of TEMPO-trapped products were formed with 16% chain transfer products (Figure 18). These results aligned with the comparable experiments conducted in bulk and confirmed the existence of PE macroradicals using TEMPO radical trapping as an analytics tool.60,61This experiment also gave a new perspective on possible simplifications of experimental setups in bulk and opened the opportunity to perform MILRad functionalization reactions in the flow, in which functionalized TEMPO derivatives can be utilized for controlled radical polymerization of block segments.

[0153] Diblock copolymer synthesis and characterization

[0154] Synthesis of polyethylene-polyacrylate block copolymers in continuous flow

[0155] With reference to Figure 6, the outlets of first pump 7 and mass flow controller (MFC) 3 are connected with the inlet of the first reactor 11 using a T-junction 9. The backpressure of the first BPR 13 is set to 250 psi. The outlet of the first BPR is connected with the outlet of second pump 17 through another T-junction 19, which is also joined with the inlet of the second reactor 19. This second reactor is placed in a Photocube™ for the free radical reaction of acrylates under the blue light irradiation provided by the 84 watt, blue LED of the Photocube™. A switch valve is placed between the first BPR 13 and the second T- junction 19 for an optional collection of PE aliquots. A second BPR 25 is placed at the outlet of the second reactor 21 and set to a backpressure of 40 psi (2.76 bar), and the synthesized block copolymer is collected in a round bottom flask (collection reservoir 27) as a stream from the outlet of the second BPR.

[0156] At first, fresh chlorobenzene (PhCl) was pumped for 3 retention times through the flow system via both pumps (fresh solvent reservoir is not shown in Figure 6). Ethylene gas was injected into the flow system using the mass flow controller (MFC) at 23 bar for 3 retention times to obtain a steady state before a reaction started. A 50 mL pear-shaped flask (reservoir 5) was flame-dried and charged with Cl catalyst solution (2.1 pmol / mL, 1 eq.) prepared in PhCl. An acrylate solution of 5.58 mmol / mL concentration was taken into another 50 mL flame-dried pear-shaped flask (reservoir 15). Then, the first pump inlets were switched from the fresh solvent reservoir to the catalyst solution reservoir (reservoir 5) for the coordination-insertion polymerization of ethylene in the first reactor 11. When the synthesized PE solution reached the second T-connector 19, the inlet of the second pump 17 was switched from the fresh solvent reservoir (not shown) to the acrylate solution. The PE-MA- macrochelate formed at the T-connector 19 was then subjected to blue light irradiation by the LED source in the Photocube™ for the free radical polymerization in the second reactor 21. The block-copolymer product was collected from the outlet of the second reactor in a round bottom flask (reservoir 27) containing triethyl silane to quench any further reaction. After the product had been collected for 30 minutes, the pump inlets were switched to the fresh PhCl to flush the flow system. The solvent from the obtained product was then removed via a rotatory evaporator. The residue was redissolved in DCM, filtered through a PTFE filter, and precipitated in MeOH. The obtained product was again dissolved in DCM and concentrated in the rotatory evaporator, then precipitated in hexane to form a cloudy suspension. The suspension was then subjected to centrifugation (1 hour at 7830 rpm) followed by decantation to separate the PE homopolymer (dissolved in the supernatant) from the block copolymer (as pellet). Finally, the obtained product was dried in vacuo and analyzed by NMR, GPC, SAXS, and DSC (Table 8).

[0157] A combination of characterizations such as size exclusion chromatography (SEC) or gel permeation chromatography (GPC), 1H NMR spectroscopy, 1H diffusion-ordered NMR spectroscopy (DOSY), small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) was performed to analyze the PE- >-PMA block copolymer synthesized in the continuous flow (Figure 7, Table 8, entry 1). GPC traces of crude PE-Z>-PMA (Figure 7A)imply a mixture of the block copolymer and unreacted PE precursor. The molecular weight (Mri) of the PE homopolymer was determined from the aliquot (14.60 kg / mol), which was utilized as a precursor for the BCP. The Mn of purified PE-A-PMA was 41.88 kg / mol with an overall 81% incorporation of MA determined from the 1HNMR spectroscopy (Figure 20). In the DOSY NMR analysis of purified PE-A-PMA (Figure 7B shows the product of entry 1 in Table 8, Figure 27 shows the product of entry 2 in Table 8), the obtained signals corresponded to PE block (1.25-0.83) ppm and PMA block (3.66, 2.32, 1.97, 1.68) were aligned in a single diffusion coefficient. This observation confirmed that formed blocks were covalently bonded with each other. In addition, the SAXS profile of purified PE-A-PMA (Figure 7C) portrayed principal scattering peaks evidencing the microphase separation (D = 56 nm, calculated as D spacing = 2m / q) of two immiscible blocks arranged in a lamellar structure. Finally, the purified block copolymer was subjected to DSC measurement. Two separate glass transition temperatures (7g) were observed in the obtained DSC traces (Figure 7D), which are in the range of the PE segment (-71 °C) and PMA segment (9 °C), indicating the presence of two heterogeneous phases in the same polymeric matrix. All these findings collectively validate the successful combination of two different homopolymer segments prepared in a sequential continuous flow system.

[0158] One observation in the GPC trace of crude PE- / >-PMA (Figure 7A) drew our attention to the fact that there was a significant extent of unconverted PE macrochelate in the obtained product. Our previous study suggested that the stable six-membered chelate formed by the acrylate monomer after the insertion must be opened for an effective Pd-C bond homolysis under the blue light irradiation as the chelate is too stable at generating the macro radical to initiate the radical polymerization.60Therefore, the Lewis base (MeCN) plays a vital role at this stage in opening the chelate to proceed to the block copolymer formation. Other complexes with ZnC12, AgBF4, AgPF4 also work, but MeCN is advantageous due to its lower cost.

[0159] An excess of MeCN also competes with monomer during the insertion and thus decreases the rate of polymerization.66’70To investigate this phenomenon, an additional amount of MeCN (5, 10, and 20 mol eq. to Cl) was added to the MA solution during theformation of PE-6-PMA polymers of Table 8, entry 2, 3, and 4, respectively. TheMz of the macro initiating PE were similar -13.5 kg / mol for all the mentioned entries. From the GPC traces of crude PE-A-PMA in Figures 19A, 19B and 19C, it is evident that the additional amount of MeCN facilitated the chelate opening efficiently so that the unreacted PE macroinitiator traces gradually became less prominent with better dispersity due to more effective conversion from PE homopolymer to block copolymer. On the contrary, a gradual decrease in Mn and MA incorporation was also observed in the obtained GPC because of a reduction in the rate of polymerization. The increasing quantities of MeCN lead to an increased concentration of propagating chains that get terminated more rapidly under the steady-state assumption in which the rate of initiation is equal to the rate of termination (Rz = R / ). For instance, without additional MeCN (entry 1), Mn was 41.88 kg / mol, while it decreased 39.89, 38.57, and 23.19 kg / mol with an additional MeCN of 5, 10, and 20 mol eq. to Cl . A similar trend was also reflected for the MA incorporation as of 70, 61, and 57% from 81%. To examine the block copolymers prepared with additional ancillary ligands, we characterized the purified PE-A-PMA (Table 8, entry 2, additional MeCN = 5 mol eq.) by conducting 'H DOSY. SAXS, and DSC analyses, 'H DOSY NMR (Figure 27) of the purified PE- / 1-PMA sample illustrated a single diffusion coefficient with corresponding PE and PMA signals. Additionally, the purified block copolymer depicted principal scattering peaks corresponding to the microphase separation (D = 36 nm) of two immiscible moieties with a lamellar structure in the SAXS experiment (Figure 31 A). In DSC traces (Figure 30A), two separate Tg were also observed in the range of PE segment (-69 °C) and PMA segment (9 °C). Considering these outcomes, the addition of 5 mol eq. MeCN for this particular reaction condition is advantageous and preferred for higher conversion of PE homopolymer to block copolymer through chain extension incorporating acrylate block of desired molecular weight.

[0160] To explore the versatility of the continuous flow system, different PE-A-PA block copolymers were prepared through MILRad under the same reaction conditions as PE-A-PMA with additional MeCN (5 mol eq.) utilizing other acrylate monomers such as ethyl acrylate (EA), n-butyl acrylate (zz-BuA, and tert-butyl acrylate ( -BuA) (Table 8, entry 5, 6, and 7). Synthesized PE-fr-PA BCPs were then purified and examined by similar characterizationmethods to confirm the desired BCP formation. For PE-A-PEA, the Mn was found to be 52.06 kg / mol in the GPC analysis (Table 8, entry 5) with 66% EA incorporation from correspondingNMR in Figure 24.XH DOSY NMR confirmed the formation of the diblock through covalent bonds by depicting the same diffusion coefficient for both PE and PEA signals (Figure 28). DSC traces of this BCP also showed separate Tg for PE and PEA segments at the characteristic temperatures -69 °C and -17 °C respectively (Figure 30D). On the other hand, the purified PE-b-P(w-BuA) polymer showed a higher molecular weight (Mn = 144.69 kg / mol) with 82% acrylate incorporation (Table 8, entry 6). The corresponding peaks of PE and P(w-BuA) blocks accumulated around the same diffusion coefficient inDOSY NMR analysis (Figure 29), and the principal scattering peaks in SAXS trace (Figure 3 IB) with D spacing of 61 nm evident the formation of the desired block copolymer. Finally, the successful preparation of PE- b-P(t-BuA) was similarly confirmed by 1H NMR and DSC experiments (Figure 26 and Figure 30F), where the GPC traces showed the Mn = 319.84 kg / mol (Table 8, entry 7).Table 8. Polyethylene-polyacrylate block copolymers"05 Steckregulator (st toe end's W radteal po^meriza^n, 2.10 ^§WL cctecerstratte.a ot2a catalyst. 30 minutes reaction toe.tettex (S) were oetetminee by get jseweation chromatography (GPC) analysis

[0161] In summary, we developed a continuous flow reactor system that combines two adverse polymerization methods, coordination-insertion and free radical polymerization, toform polar polyolefin block copolymers in which a PA segment follows a PE segment. We demonstrated that the heterogeneous droplet flow is ideal as the gaseous phase is not only used to control the flow system dynamics but also carries the gaseous ethylene monomer. We could maintain a living coordination-insertion polymerization of ethylene in the continuous flow, and a systematic investigation of the influences of flow parameters on the corresponding molecular weight and yield of prepared PE homopolymers utilizing a diimine Pdll complex was executed. This investigation additionally facilitated the preparation of PE homopolymers of any desired Mn without alternating other flow conditions and experimental setups. The switch from one polymerization mechanism to the other was facilitated by the addition of acrylate monomers generating macrochelates and retarding the ethylene polymerization by irradiation of light and with the start of the radical pathway through the formation of macroradicals. Although ethylene is still present in the gaseous phase, it does not compete with the light-initiated radical pathway. TEMPO trapping experiments illustrated the successful formation of the PE macroinitiator by combining the two separate flow setups sequentially, which established the radical switch to form a polyacrylate segment. A broad range of molecular weights and compositions for PE-A-PMA was achieved on this platform, and several polyethylene-polyacrylate BCPs were generated using different acrylate monomers. We demonstrated that the continuous-flow polymer synthesis technique is a striking tool for producing these advanced polymeric materials through MILRad polymerization with precisely controlled architectures and desirable properties, which can pave the way for a wide range of applications.

[0162] Any of the examples or embodiments described herein may include various other features in addition to or in lieu of those described above. The teachings, expressions, embodiments, examples, etc., described herein should not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined should be clear to those skilled in the art in view of the teachings herein.

[0163] Having shown and described exemplary embodiments of the subject matter contained herein, further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications without departing from the scope of the claims. In addition, where methods and steps described above indicate certain events occurring in certain order, it is intended that certain steps do not have to be performed in the order described but in any order as long as the steps allow the embodiments to function for their intended purposes. Therefore, to the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Some such modifications should be apparent to those skilled in the art. For instance, the examples, embodiments, geometries, materials, dimensions, ratios, steps, and the like discussed above are illustrative. Accordingly, the claims should not be limited to the specific details of structure and operation set forth in the written description and drawings.ENUMERATED EMBODIMENTS (EEs)

[0164] EE1. A continuous flow reactor system for the synthesis of polyolefin-polar block copolymers comprising: a) a first tubular reactor having an inlet end and an outlet end, the inlet end in fluid communication with a source of olefin and a source of a catalyst; b) a first backpressure regulator valve having an inlet end and an outlet end, the inlet end in fluid communication with the outlet end of the first tubular reactor for controlling internal pressure of the first tubular reactor; c) a second tubular reactor having an inlet end and an outlet end, the inlet end in fluid communication with a source of a polar monomer and a first reaction product of the first tubular reactor; d) a source of blue light in optical communication with the second tubular reactor; e) a second backpressure regulator valve having an inlet end and an outlet end, the inlet end in fluid communication with the outlet end of the second tubular reactor for controlling internal pressure of the second tubular reactor; and f) a collection vessel for collecting a polyolefin-polar block copolymer product.

[0165] EE2. The system of EE 1, further comprising a first pump for pressurizing the source of catalyst to the inlet of the first reactor.

[0166] EE3. The system of EE 1 or 2, further comprising a second pump for pressurizing the source of polar monomer to the inlet of the second reactor.

[0167] EE4. The system of any one of EEs 1-3, further comprising a mass flow controller for controlling the flow of olefin to the inlet of the first reactor.

[0168] EE5. The system of any one of EEs 1-4, wherein the source of blue light has a wavelength of approximately 457 nanometers.

[0169] EE6. The system of any one of EEs 1-6, wherein the source of blue light is positioned external to the second tubular reactor.

[0170] EE7. The system of any one of EEs 1-7, further comprising a valve positioned downstream of the first backpressure regulator for withdrawing aliquots of polyethylene from the system.

[0171] EE8. A polyolefin-polar block copolymer produced by the continuous flow reactor system of any one of EEs 1 to 7.

[0172] EE9. A method of producing polyolefin-polar block copolymers comprising: a) combining olefin monomers in a gas phase with a catalyst in a liquid phase to produce a polyolefin-catalyst precursor; b) combining an acrylate monomer with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate; and c) exposing the catalyst polyolefin macrochelate in the presence of acrylate monomer to blue light to form a polyolefin-polar block copolymer.

[0173] EE10. A method of producing polyolefin-polar block copolymers comprising: a) providing a continuous flow reactor system capable of enabling a gas phase and a liquid phase in reactive communication; b) combining olefin monomers in the gas phase with a catalyst in the liquid phase to produce a polyolefin-catalyst precursor; c) combining an acrylate monomer with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate; and d) exposing the polyolefin macrochelate in the presence of acrylate monomer in the liquid phase to blue light to form a polyolefin-polar block copolymer.

[0174] EE11. The method of EE 9, wherein the catalyst is added only in step a); or the method of EE 10, wherein the catalyst is added only in step b).

[0175] EE12. The method of EE 11, wherein the catalyst is a cationic diimine Pd^ complex.

[0176] EE13. The method of EE 11, wherein the catalyst is [(Ar-N=C(Me)-C(Me)=N-Ar)Pd(Me)(CH3CN)]+ [B(3,5-C6H3(CF3)2)4].

[0177] EE14. The method of any one of EEs 9-13, wherein the olefin is ethylene, propylene or butadiene.

[0178] EE15. The method of any one of EEs 9-14, wherein the acrylate monomer is methacrylate, ethyl acrylate, n-butyl acrylate or t-butyl acrylate.

[0179] EE16. The method of any one of EEs 9-15, wherein the concentration of catalyst in the liquid phase is from 1 to 50 pmol / ml.

[0180] EE17. The method of any one of EEs 9-16, in which the catalyst is one selectedfrom

[0181] EE18. A block copolymer produced by the method of any one of EEs 9-17.

[0182] EE19. Use of a continuous flow reactor system comprising a first tubular reactor configured to maintain a plurality of volumes comprising gas phases comprising an olefin monomer separated by interfacial contact with a liquid phase comprising a catalyst and any catalyst-polyolefin precursor product of contact of the olefin monomer with the catalyst, and a second reactor configured to maintain a plurality of volumes comprising gas phasescomprising an olefin monomer separated by interfacial contact with a liquid phase comprising an acrylate monomer, the catalyst-polyolefin precursor and any product catalyst-polyolefin macrochelate, and further configured to expose a volume of the liquid phase to blue light, to produce a polyolefin-polar block copolymer.

[0183] EE20. The use of EE 19, wherein the catalyst is a cationic diimine Pd^ complex.

[0184] EE21. The use of EE 20, wherein the catalyst is [(Ar-N=C(Me)-C(Me)=N-Ar)Pd(Me)(CH3CN)]+ [B(3,5-C6H3(CF3)2)4].

[0185] EE22. The use of any one of EEs 19-21, wherein the olefin is ethylene, propylene or butadiene.

[0186] EE23. The use of any one of EEs 19-22, wherein the acrylate monomer is methacrylate, ethyl acrylate, n-butyl acrylate or t-butyl acrylate.

[0187] EE24. The use of any one of EEs 19-23, wherein the concentration of catalyst in the liquid phase is from 1.0 to 50 pmol / ml.

[0188] EE25. The use of any one of EEs 19-24, wherein the catalyst is one selected from

[0189] EE26. A block copolymer produced by the use of any one of EEs 19-25.

[0190] EE27. Use of a gaseous olefin monomer, a cationic diimine Pd^ complex in a liquid phase, and an acrylate monomer in a liquid phase to produce a polyolefin-polar block copolymer.

[0191] EE28. The use of EE 27, wherein a polyolefin block of the copolymer is formed by living coordination-insertion polymerization of the olefin monomer at an interface of the gas and liquid phases and the polar block of the copolymer is formedby Metal-organic Insertion Light-initiated Radical polymerization of a Pd- polyethylene macrochelate.

[0192] EE29. The use of EE 27 or EE 28, wherein the catalyst is [(Ar-N=C(Me)-C(Me)=N-Ar)Pd(Me)(CH3CN)]+ [B(3,5-C6H3(CF3)2)4].

[0193] EE30. The use of any one of EEs 26-29, wherein the olefin is ethylene, propylene or butadiene.

[0194] EE31. The use of any one of EEs 26-30, wherein the acrylate monomer is methacrylate, ethyl acrylate, n-butyl acrylate or t-butyl acrylate.

[0195] EE32. The use of any one of EEs 26-31, wherein the concentration of catalyst in the liquid phase is from 1.0 to 50 pmol / ml.EE33. The use of any one of EEs 26-32, in which the catalyst is one selected from

[0196] EE34. A polyolefin-polar block copolymer produced by the use of any one of EEs 26-33.

[0197] EE35. A method of producing polyolefin-polar block copolymers comprising: a) partitioning olefin monomers in a gas phase into a liquid phase comprising a catalyst and polymerizing the olefin monomers by coordination-insertion polymerization to produce a polyolefin-catalyst precursor in the liquid phase; b) mixing an acrylate monomer in a liquid phase with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate; andc) exposing the catalyst polyolefin macrochelate in the presence of acrylate monomer to light to form a polyolefin-polar block copolymer by Metal-organic Insertion Light-initiated Radical polymerization .

[0198] EE36. The method of EE 35, wherein the catalyst is a cationic diimine Pd^ complex.

[0199] EE37. The method of EE36, wherein the catalyst is [(Ar-N=C(Me)-C(Me)=N-Ar)Pd(Me)(CH3CN)]+ [B(3,5-C6H3(CF3)2)4].

[0200] EE38. The method of any one of EEs 35-37, wherein the olefin is ethylene, propylene or butadiene.

[0201] EE39. The method of any one of EEs 35-38, wherein the acrylate monomer is methacrylate, ethyl acrylate, n-butyl acrylate or t-butyl acrylate.

[0202] EE40. The method of any one of EEs 35-39, wherein the concentration of catalyst in the liquid phase is from 1.0 to 50 pmol / ml.EE41. The method of any one of EEs 35-40, wherein the catalyst is one selected fromSiyi a Harf-

[0203] EE41. A block copolymer produced by the method of any one of EEs 35-40.

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Claims

CLAIMSWe claim:

1. A method of producing polyolefin-polar block copolymers comprising: a) combining olefin monomers in a gas phase with a catalyst in a liquid phase to produce a polyolefin-catalyst precursor; b) combining an acrylate monomer with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate; and c) exposing the catalyst polyolefin macrochelate in the presence of acrylate monomer to blue light to form a polyolefin-polar block copolymer.

2. The method of claim 1, wherein the catalyst is added only in step a)3. The method of claim 1 or 2, wherein the catalyst is a cationic diimine Pd^ complex.

4. The method of any one of claims 3, wherein the catalyst is [(Ar-N=C(Me)-C(Me)=N- Ar)Pd(Me)(CH3CN)]+ [B(3,5-C6H3(CF3)2)4].

5. The method of any one of claims 1-4, wherein the olefin is ethylene, propylene or butadiene.

6. The method of any one of claims 1-5, wherein the acrylate monomer is methacrylate, ethyl acrylate, n-butyl acrylate or t-butyl acrylate.

7. The method of any one of claims 1-6, wherein the concentration of catalyst in the liquid phase is from 1.0 to 50 pmol / ml.

8. The method of any one of claims 1-7, in which the catalyst is one selected from9. The method of any one of claims 1-8, wherein the step a) comprises partitioning olefin monomers in a gas phase into a liquid phase comprising a catalyst and polymerizing the olefin monomers by coordination-insertion polymerization to produce a polyolefin-catalyst precursor in the liquid phase.

10. The method of any one of claims 1-9, wherein the step b) comprises mixing an acrylate monomer in a liquid phase with the polyolefin-catalyst precursor to form a catalyst-polyolefin macrochelate11. The method of any one of claims 1-10, wherein the step c) comprises exposing the catalyst polyolefin macrochelate in the presence of acrylate monomer to light to form a polyolefin-polar block copolymer by Metal-organic Insertion Light-initiated Radical polymerization .

12. The method of any one of claims 1-11 that is performed using a continuous flow reactor system comprising: a) a first tubular reactor having an inlet end and an outlet end, the inlet end in fluid communication with a source of olefin and a source of a catalyst; b) a first backpressure regulator valve having an inlet end and an outlet end, the inlet end in fluid communication with the outlet end of the first tubular reactor for controlling internal pressure of the first tubular reactor; c) a second tubular reactor having an inlet end and an outlet end, the inlet end in fluid communication with a source of an acrylate monomer and a first reaction product of the first tubular reactor; d) a source of blue light in optical communication with the second tubular reactor; e) a second backpressure regulator valve having an inlet end and an outlet end, the inlet end in fluid communication with the outlet end of the second tubular reactor for controlling internal pressure of the second tubular reactor; and f) a collection vessel for collecting a polyolefin-polar block copolymer product.

13. The method of claim 12, wherein the continuous flow reactor system further comprises a first pump for pressurizing the source of catalyst to the inlet of the first reactor.

14. The method of claim 13, wherein the continuous flow reactor system further comprises a second pump for pressurizing the source of acrylate to the inlet of the second reactor.

15. The method of claim 14, wherein the continuous flow reactor system further comprises a mass flow controller for controlling the flow of olefin to the inlet of the first reactor.

16. The method of any one of claims 12-15, wherein the source of blue light has a wavelength of approximately 457 nanometers.

17. A block copolymer produced by the method of any one of claims 1-16.

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