Biocatalytic synthesis of polymers. Synthesis of an optically active,epoxy-substituted polyester by lipase-catalyzed polymerization

The enantioselective polymerization of bis(2,2,2-trichloroethyl) trans-3,4-epoxyadipate with 1,4-butanediol using the enzyme porcine pancreatic lipase as a catalyst is described. The polymerization was carried out at ambient temperature in anhydrous ethyl ether. End group analysis provided M_N = 5,300 daltons, whereas GPC provided M_w = 7,900 daltons for the polymer. The unchanged (+)-enantiomer of the diester was shown to have an enantiomeric purity of > 95% by proton NMR in the presence of the chiral shift reagent Eu(hfc)₃. The stereochemical purity of the (?)-polymer was estimated at > 96% by consideration of the amount of the slower reacting enantiomer that could have been incorporated and still attain the observed degree of polymerization (25) when the starting ratio of racemic diester to diol was 2:1. Direct determination of the stereochemical purity of the polymer using Eu(hfc)₃ was unsuccessful. Similar studies on polymer having random stereochemical orientations of the epoxide showed that such polymers do not behave as if they are racemic in the presence of the shift reagent. The polymer required for the latter studies was prepared by epoxidation of the product from enzyme catalyzed polymerization of bis(2,2,2-trichloroethyl) trans-3-hexenedioate with 1,4-butanediol.     

Spectroscopic Studies on the Simple Rcooh System

The carbonyl stretching vibration of monocarboxylic acid in CCl₄ solution has been investigated. We introduce a new “m-factor” to study the polymerization of this simple RCOOH system. The value of “m-factor” was evaluated and tested in different concentrations and temperatures. Three classes of acid polymers were found as followings: linear dimer in class I (m?2); linear and cyclic dimers in class II (m?4); linear, cyclic dimers, and linear trimer in class III (m?8). A linear relationship between log K₁ and (??1)/(2?+1) was found.     

Polymerization of cyclic acetals. I. Polymerization of 1,3,6-trioxacyclooctane and copolymerization with p-methoxystyrene

The polymerization of 1,3,6-trioxacyclooctane initiated by trityl salts with various counterions in CH₂Cl₂ was investigated. The reaction mixtures and the isolated polymers were analyzed by GPC (double detection—IR and UV at 254 nm),¹H-, and¹³C-NMR spectroscopy. In the early stage of polymerization only oligomers (mainly cyclic) were formed. With longer reaction times, linear polymers (yield 86–94%, M = 70,000–80,000) were obtained. The concentration of each individual oligomer passed through a maximum and decreased, reaching its equilibrium concentration. The time interval necessary to reach the maximum concentration increased with n. The total concentration of the oligomers was 0.2 mol L^?1 regardless of the initiator used. Conditions for polymerization with virtually no termination were found. Addition of p-methoxystyrene to the “living” polyacetals resulted in block copolymers. GPC,¹H- and ¹³C-NMR and acidolytic degradation were used to prove the formation of AB block copolymers. The reactive alkoxycarbenium growing species are responsible for the formation of block polyacetal-polymethoxystyrene copolymer.     

Synthesis and polymerization reactions of cyclic imino ethers. 5: naphthalene unit‐containing poly(ether amide)s

Poly(ether amide)s containing naphthalene unit were prepared either by the polyaddition reaction of aromatic bis(2‐oxazoline)s with the different dihydroxynaphthalenes or by the homopolyaddition of a monomer containing an oxazoline, a hydroxy, and naphthalene moieties. First, polymerization method represents AA + BB mode where 1,4‐phenylene‐2,2′‐bis(2‐oxazoline) (A) and 1,3‐phenylene‐2,2′‐bis(2‐oxazoline) (B) were used as AA monomers and four different dihydroxynaphthalenes 1–4 were used as BB monomers. In the second case, 2‐(6‐hydroxynaphthalene‐2‐yl)‐2‐oxazoline (5) was used as AB‐type monomer in thermally induced polymerizations. The time dependences of polyadditions in bulk as well as in the solution were examined. The reduction of molar mass was observed after the initial fast increase of molar mass. This can be explained by the presence of side and degradation reactions. In both cases, polyadditions resulted in the linear poly(ether amide)s, which were characterized by ¹H and ¹³C NMR spectroscopy. Thermal properties of the prepared polymers were studied by differential scanning calorimetry (DSC) measurements. Comparison of the temperatures of glass transition for polymers prepared in AA + BB mode shows the strong dependence of thermal properties on the structure of the polymers. The values were in the range of 136–171°C. The glass‐transition temperature (T_g) of poly[2‐(6‐hydroxynaphthalene‐2‐yl)‐2‐oxazoline] prepared by AB‐type polyaddition is 183°C, which corresponds to the higher contents of hard aromatic segments in the latter type of polymers compared to the polymers prepared in the AA + BB‐type polyadditions. The described polymers represent novel naphthalene unit‐containing poly(ether amide)s for different applications in material science. Copyright © 2011 John Wiley & Sons, Ltd.     

A New Approach for the Synthesis of Miktoarm Star Polymers Through a Combination of Thiol–Epoxy “Click” Chemistry and ATRP/Ring‐Opening Polymerization Techniques

A new approach was developed for synthesis of certain A₃B₃‐type of double hydrophilic or amphiphilic miktoarm star polymers using a combination of “grafting onto” and “grafting from” methods. To achieve the synthesis of desired miktoarm star polymers, acetyl protected poly(ethylene glycol) (PEG) thiols (M_n = 550 and 2000 g mol^?1) were utilized to generate A₃‐type of homoarm star polymers through an in situ protective group removal and a subsequent thiol–epoxy “click” reaction with a tris‐epoxide core viz. 1,1,1‐tris(4‐hydroxyphenyl)ethane triglycidyl ether. The secondary hydroxyl groups generated adjacent to the core upon the thiol–epoxy reaction were esterified with α‐bromoisobutyryl bromide to install atom transfer radical polymerization (ATRP) initiating sites. ATRP of N‐isopropylacrylamide (NIPAM) using the three‐arm star PEG polymer fitted with ATRP initiating sites adjacent to the core afforded A₃B₃‐type of double hydrophilic (PEG)₃[poly(N‐isopropylacrylamide)] (PNIPAM)₃ miktoarm star polymers. Furthermore, the generated hydroxyl groups were directly used as initiator for ring‐opening polymerization of ε‐caprolactone to prepare A₃B₃‐type of amphiphilic (PEG)₃[poly(ε‐caprolactone)]₃ miktoarm star polymers. The double hydrophilic (PEG)₃(PNIPAM)₃ miktoarm star polymers showed lower critical solution temperature around 34 °C. The preliminary transmission electron microscopy analysis indicated formation of self‐assembly of (PEG)₃(PNIPAM)₃ miktoarm star polymer in aqueous solution. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 146–156     

Living cationic polymerization of vinyl ethers with carboxylic acid/tin tetrahalide initiating systems. I. New initiating systems based on acetic acid and selection of Lewis acid and basic additive leading to living polymers with low polydispersity

Cationic polymerization of isobutyl vinyl ether (IBVE) with acetic acid (CH₃COOH)/tin tetrahalide (SnX₄: X = Cl, Br, I) initiating systems in toluene solvent at 0°C was investigated, and the reaction conditions for living polymerization of IBVE with the new initiating systems were established. Among these tin tetrahalides, SnBr₄ was found to be the most suitable Lewis acid to obtain living poly(IBVE) with a narrow molecular weight distribution (MWD). The polymerization with the CH₃COOH/SnBr₄ system, however, was accompanied with the formation of a small amount of another polymer fraction of very broad MWD, probably due to the occurrence of an uncontrolled initiation by SnBr₄ coupled with protonic impurity. Addition of 1,4-dioxane (1–1.25 vol %) or 2,6-di-tert-butylpyridine (0.1–0.6mM) to the polymerization mixture completely eliminated the uncontrolled polymer to give only the living polymer with very narrow MWD (M _w/M _n ≤ 1.1; M _w, weight-average molecular weight; M _n, number-average molecular weight). The M _n of the polymers increased in direct proportion to monomer conversion, continued to increase upon sequential addition of a fresh monomer feed, and was in good agreement with the calculated values assuming that one CH₃COOH molecule formed one polymer chain. Along with these results, kinetic study and direct ¹H-NMR observation of the living polymerization indicated that CH₃COOH and SnBr₄ act as so-called “initiator” and “activator”, respectively, and the living polymerization proceeds via an activation of the acetate dormant species. The basic additives such as 1,4-dioxane and 2,6-di-tert-butylpyridine would serve mainly as a “suppressor” of the uncontrolled initiation by SnBr₄. The polymers produced after quenching the living polymerization with methanol possessed the acetate dormant terminal and they induced living polymerization of IBVE in conjunction with SnBr₄ in the presence of 1,4-dioxane. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3173–3185, 1998     

Synthesis of star‐shaped poly(vinyl ethers) with many arms by living cationic polymerization

Star‐shaped polymers of isobutyl vinyl ether (IBVE) with many arms (“crew cut” type) have been synthesized by living cationic polymerization using the HCl‐IBVE adduct/ZnCl₂ initiating system. A short living polymer (DP_n ⪇ 30) of IBVE is allowed to react with a large amount of divinyl ether ([divinyl ether]₀/[P*] = 10–15) to give soluble star polymers whose number of arms ranged from 40 to 120. The diameter of such “crew cut” star polymers reached ca. 20 nm.     

Thiol‐epoxy polymerization via an AB monomer: Synthetic access to high molecular weight poly(β‐hydroxythio‐ether)s

A synthetic route is developed for the preparation of an AB‐type of monomer carrying an epoxy and a thiol group. Base‐catalyzed thiol‐epoxy polymerization of this monomer gave rise to poly(β‐hydroxythio‐ether)s. A systematic variation in the reaction conditions suggested that tetrabutyl ammonium fluoride, lithium hydroxide, and 1,8‐diazabicycloundecene (DBU) were good polymerization catalysts. Triethylamine, in contrast, required higher temperatures and excess amounts to yield polymers. THF and water could be used as polymerization mediums. However, the best results were obtained in bulk conditions. This required the use of a mechanical stirrer due to the high viscosity of the polymerization mixture. The polymers obtained from the AB monomer route exhibited significantly higher molecular weights (M_w = 47,700, M_n = 23,200 g/mol) than the materials prepared from an AA/BB type of the monomer system (M_w = 10,000, M_n = 5400 g/mol). The prepared reactive polymers could be transformed into a fluorescent or a cationic structure through postpolymerization modification of the reactive hydroxyl sites present along the polymer backbone. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2040–2046     

Partially biobased polymers: The synthesis of polysilylethers via dehydrocoupling catalyzed by an anionic iridium complex

Partially biobased polysilylethers (PSEs) are synthesized via dehydrocoupling polymerization catalyzed by an anionic iridium complex. Different types (AB type or AA and BB type) of monomers are suitable. Levulinic acid (LA) and succinic acid (SA) have been ranked within the top 10 chemicals derived from biomass. BB type monomers (diols) derived from LA and SA have been applied to the synthesis of PSEs. The polymerization reactions employ an air-stable anionic iridium complex bearing a functional bipyridonate ligand as catalyst. Moderate to high yields of polymers with number-average molecular weights (M_n) up to 4.38 × 10⁴ were obtained. A possible catalytic cycle via an Ir-H species is presented. Based on the results of kinetic experiments, apparent activation energy of polymerization in the temperature range of 0–10 °C is about 38.6 kJ/mol. The PSEs synthesized from AA and BB type monomers possess good thermal stability (T₅ = 418 °C to 437 °C) and low glass-transition temperature (T_g = −49.6 °C).     

“Living” radical polymerization of methyl methacrylate with diethyl 2,3-dicyano-2,3-diphenylsuccinate as a thermal iniferter

The bulk polymerization of methyl methacrylate (MMA) initiated with diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS) was studied. This polymerization showed some “living” characteristics; that is, both the yield and the molecular weight of the resulting polymers increased with reaction time, and the resultant polymer can be extended by adding MMA. The molecular weight distribution of PMMA obtained at high conversion is fairly narrow (M_w/M_n = 1.24≈1.34). It was confirmed that DCDPS can serve as a thermal iniferter for MMA polymerization by a “living” radical mechanism. Furthermore, the PMMA obtained can act as a macroinitiator for radical polymerization of styrene (St) to give a block copolymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4610–4615, 1999     

Amphiphilic polymethacrylates as crosslinked polymer precursors obtained by free‐radical monomethacrylate/dimethacrylate copolymerizations

As an extension of our work on the elucidation of the mechanism and control of 3‐dimensional network formation in the free‐radical crosslinking polymerization and copolymerization of multivinyl compounds with the aim to molecularly design vinyl‐type network polymers, novel amphiphilic polymers were prepared as crosslinked polymer precursors. Thus, benzyl methacrylate, a nonpolar monomer, was copolymerized radically with 5 mol % of triicosaethylene glycol dimethacrylate [CH₂C(CH₃)CO(OCH₂CH₂)₂₃OCOC(CH₃)CH₂], a polar monomer, in the presence of lauryl mercaptan as a chain transfer agent. The resulting prepolymers (i.e., vinyl‐type network‐polymer precursors or amphiphilic polymers) were characterized mainly by viscometry using t‐butylbenzene (t‐BB) and a t‐BB/MeOH (80/20) mixture as solvents. The viscosities in the t‐BB/MeOH (80/20) mixture were quite high compared with those in t‐BB, and completely reversed concentration dependencies were observed in the solvents. These are discussed by considering the difference in conformation and the shrinkage of polar, flexible polyoxyethylene units or the entanglement of nonpolar, rigid primary chains. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4396–4402, 2000     

Cationic polymerization of p-methylstyrene initiated by acetyl perchlorate: An approach to living polymerization

The cationic polymerization of p-methylstyrene initiated by acetyl perchlorate at ?78°C led to long-lived (living-like) polymers with a narrow molecular weight distribution (M?_w/M?_n = 1.1–1.4) in methylene chloride containing a common ion salt (n-Bu₄NClO₄) or in a less polar solvent (CH₂Cl₂/toluene, 1/4v/v). Under these conditions, the number-average molecular weight (M?_n) of the polymers increased in proportion to monomer conversion and was regulated by the monomer-to-initiator ratio. When fresh feeds of the monomer were repeatedly added to a completely polymerized solution, the polymerization ensued at the same rate as before and the linear increase in M?_n with monomer conversion continued. The effects of solvent polarity and the common ion salt on the polymerization showed the suppression of the ionic dissociation of the propagating species, resulting in a “nondissociated species,” to be the key factor for the formation of the long-lived polymers.     

Preparation and characterization of solution processable phthalocyanine‐containing polymers via a combination of RAFT polymerization and post‐polymerization modification techniques

In this work, a benzenedinitrile functionalized monomer, 2‐methyl‐acrylic acid 6‐(3,4‐dicyano‐phenoxy)‐hexyl ester, was successfully polymerized via the reversible addition‐fragmentation chain transfer method. The polymerization behavior conveyed the characteristics of “living”/controlled radical polymerization: the first‐order kinetics, linear increase of number‐average molecular weight with monomer conversion, narrow molecular weight distribution, and successful chain‐extension experiment. The soluble Zn(II) phthalocyanine (Pc)‐containing (ZnPc) polymers were achieved by post‐polymerization modification of the obtained polymers. The Zn(II) phthalocyanine‐functionalized polymer was characterized by FTIR, UV–vis, fluorescence, atomic absorption spectroscopy, and thermogravimetric analysis. The potential application of above ZnPc‐functionalized polymer as electron donor material in bulk heterojunction organic solar cell was studied. The device with ITO/PEDOT:PSS/ZnPc‐Polymer/PC₆₁BM/LiF/Al structure provided a power conversion efficiency of 0.014%, fill factor of 0.24, open circuit voltage (V_oc) of 0.21 V, and short‐circuit current (J_sc) of 0.28 mA/cm². © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 691–698     

Preparation of molecularly imprinted polymers via atom transfer radical “bulk” polymerization

The first application of atom transfer radical “bulk” polymerization (ATRBP) in molecular imprinting is described, which provides molecularly imprinted polymers (MIPs) with obvious imprinting effects towards the template, very fast binding kinetics, and an appreciable selectivity over structurally related compounds. In comparison with the MIP prepared via the normally used traditional “bulk” free radical polymerization (BFRP), the MIPs obtained via ATRBP showed somewhat lower binding capacities and apparent maximum numbers N_max for high‐affinity sites as well as quite similar binding association constants K_a for high‐affinity sites and high‐affinity site densities, in contrast with the previous reports (e.g., nitroxide/iniferter‐mediated “bulk” polymerization provided MIPs with improved properties). This is tentatively ascribed to the occurrence of rather fast gelation process in ATRBP, which greatly restricted the mobility of the chemical species, leading to a heavily interrupted equilibrium between dormant species and active radicals and heterogeneous polymer networks. In addition, the general applicability of ATRBP was also confirmed by preparing MIPs for different templates. This work clearly demonstrates that applying controlled radical polymerizations (CRPs) in molecular imprinting not always benefits the binding properties of the resultant MIPs, which is of significant importance for the rational use of CRPs in generating MIPs with improved properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 532–541, 2010     

Silylium dual catalysis in living polymerization of methacrylates via In situ hydrosilylation of monomer

Silylium ions (“R₃Si⁺”) are found to catalyze both 1,4‐hydrosilylation of methyl methacrylate (MMA) with R₃SiH to generate the silyl ketene acetal initiator in situ and subsequent living polymerization of MMA. The living characteristics of the MMA polymerization initiated by R₃SiH (Et₃SiH or Me₂PhSiH) and catalyzed by [Et₃Si(L)]⁺[B(C₆F₅)₄]^– (L = toluene), which have been revealed by four sets of experiments, enabled the synthesis of the polymers with well‐controlled M_n values (identical or nearly identical to the calculated ones), narrow molecular weight distributions (? = 1.05–1.09), and well defined chain structures {H? [MMA]_n? H}. The polymerization is highly efficient too, with quantitative or near quantitative initiation efficiencies (I* = 96–100%). Monitoring of the reaction of MMA + Me₂PhSiH + [Et₃Si(L)]⁺[B(C₆F₅)₄]^– (0.5 mol%) by ¹H NMR provided clear evidence for in situ generation of the corresponding SKA, Me₂C?C(OMe)OSiMe₂Ph, via the proposed “Et₃Si^+”‐catalyzed 1,4‐hydrosilylation of monomer through “frustrated Lewis pair” type activation of the hydrosilane in the form of the isolable silylium‐silane complex, [Et₃Si? H? SiR₃]⁺[B(C₆F₅)₄]^–. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1895–1903     

Some aspects of plasma polymerization of fluorine-containing organic compounds. II. Comparison of ethylene and tetrafluoroethylene

Plasma polymerizations of ethylene and tetrafluoroethylene are compared. In the plasma polymerization of ethylene and of tetrafluoroethylene, glow characteristics play an important role. Glow characteristic is dependent on a combined factor of W/F_m, where W is discharge power and F_m is monomer flow rate. At higher flow rates, higher wattages are required to maintain “full glow.” In the plasma polymerization of tetrafluoroethylene, simultaneous decomposition of the monomer competes with plasma polymerization. Above a certain value of W/F_m, decomposition becomes the predominant reaction, and the polymer deposition rate decreases with increasing discharge power. ESCA results indicate that the plasma polymer of tetrafluoroethylene that is formed in an incomplete glow region (low W/F_m) is a hybrid of polymers of plasma polymerization and of plasma-induced polymerization of the monomer. Polymers formed under conditions of high W/F_m to produce “full glow” are similar, regardless of the extent of decomposition of the monomer. They contain carbons with different numbers of F(CF₃, ? CF₂? , >CF? , >C<) and carbons bonded to other more electronegative substituents.     

Chain transfer by addition–substitution–fragmentation mechanism. I. End–functional polymers by a single-step free radical transfer reaction: Use of a new allylic linear peroxyketal

A new chain transfer agent, ethyl 2-[1-(1-n-butoxyethylperoxy) ethyl] propenoate (EBEPEP) was used in the free radical polymerization of methyl methacrylate (MMA), styrene (St), and butyl acrylate (BA) to produce end-functional polymers by a radical addition–substitution–fragmentation mechanism. The chain transfer constants (C_tr) for EBEPEP in the three monomers polymerization at 60°C were determined from measurements of the degrees of polymerization. The C_tr were determined to be 0.086, 0.91, and 0.63 in MMA, St, and BA, respectively. EBEPEP behaves nearly as an “azeotropic” transfer agent for styrene at 60°C. The activation energy, E_atr, for the chain transfer reaction of EBEPEP with PMMA radicals was determined to be 29.5 kJ/mol. Thermal stability of peroxyketal EBEPEP in the polymerization medium was estimated from the DSC measurements of the activation energy, E_ath = 133.5 kJ/mol, and the rate constants, k_th, of the thermolysis to various temperature. © 1994 John Wiley & Sons, Inc.     

Polymerization of butadiene sulfone

Polymerization of butadiene sulfone (BdSO₂) by various catalysts was studied. Azobisisobutyronitrile (AIBN), butyllithium, tri-n-butylborn (n-Bu)₃B, boron trifluoride etherate, Ziegler catalyst, and γ-radiation were used as catalysts. Butadiene sulfone did not polymerize with these catalysts at low temperatures (below 60°C.), but polymers were obtained at high temperature with AIBN or (n-Bu)₃B. The polymerization of BdSO₂ initiated by AIBN in benzene at 80–140°C. was studied in detail. The obtained polymers were white, rubberlike materials and insoluble in organic solvents. The polymer composition was independent of monomer and initiator concentrations and reaction time. The sulfur content in polymer decreased with increasing polymerization temperature. The polymers prepared at 80 and 140°C. have the compositions (C₄H₆)_1.55- (SO₂) and (C₄H₆)_3.14(SO₂), respectively, and have double bonds. These polymers were not alternating copolymers of butadiene with sulfur dioxide. The polymerization mechanism was discussed from polymerization rate, polymer composition, and decomposition rate of BdSO₂. From these results, the polymerization was thought to be “decomposition polymerization,” i.e., butadiene and sulfur dioxide, formed by the thermal decomposition of BdSO₂, copolymerized.     

Controlled free radical ring-opening polymerization and chain extension of the “living” polymer

Free radical ring-opening polymerization of 2-methylene-1,3-dioxepane (MDP) in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO) has been achieved to afford a chain polyester (PMDP) with di-t-butyl peroxide (DTBP) as an initiator at 125°C. The polydispersity of the polymers decreases as the concentration of TEMPO is increased. At high TEMPO concentrations, the polydispersity as low as 1.2 was obtained, which is below the theoretical lower limit for a conventional free radical polymerization. A linear relationship between the number-average molecular weight (M_n) and the monomer conversion was observed with the best-fit line passing very close to the origin of the M_n-conversion plot. The isolated and purified TEMPO-capped PMDP polymers have been employed to prepare chain extended polymers upon addition of more MDP monomer. These results are suggestive of the “living” polymerization process. A possible polymerization mechanism might involve thermal homolysis of the TEMPO-PMDP bonds followed by the addition of the monomers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 761–771, 1998     

Synthesis of ultra‐high molecular weight polymers by controlled production of initiating radicals

This study demonstrates that the gradual and slow production of initiating radicals (i.e., hydroxyl radicals here) is the key point for the synthesis of ultra‐high molecular weight (UHMW) polymers via controlled radical polymerization. Hydrogen peroxide (H₂O₂) and ferrous iron (Fe²⁺) react via Fenton redox chemistry to initiate RAFT polymerization. This work presents two enzymatic‐mediated (i.e., Bio‐Fenton‐RAFT and Semi Bio‐Fenton‐RAFT) and one syringe pump‐driven Fenton‐RAFT polymerization processes in which the initiating radicals are carefully and gradually dosed into the reaction solution. The “livingness” of the synthesized UHMW polymers is demonstrated by chain extension and aminolysis experiments. Zimm plots obtained from static light scattering (SLS) technique are used to characterize the UHMW polymers. This Fenton‐RAFT polymerization provides access to polymers of unprecedented UHMW (M_w ~ 20 × 10⁶ g mol^?1) with potential in diverse applications. The UHMW polymers made via the controlled Fenton‐RAFT polymerization by using a syringe pump shows that it is possible to produce such materials through an easy‐to‐set up and scalable process. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1922–1930