Ring-opening Metathesis Polymerization Reactions Research Articles

Upgrading of thermosets and composites via sequential frontal ring-opening metathesis polymerization and radical reactions

Upgrading of thermosets and composites via sequential frontal ring-opening metathesis polymerization and radical reactions

Structural and thermodynamic insights into the coordination preference of norbornadiene with the initiator complex [RuCl2(PPh3)2(piperidine)] in polymerization via olefin metathesis.

The metathesis reaction has been an important tool in both organic and inorganic synthetic chemistry. More specifically in polymer chemistry, ring opening metathesis polymerization (ROMP), via the formation of an active metal-carbene species (MCHR), has been widely used. The elucidation of the mechanism for ROMP opened the way for the development of well-defined catalysts, suited to local conditions. In the present study, we employed density functional theory (DFT) to investigate three reaction pathways for the formation of a species capable of activating ROMP. The active species is formed from the [RuCl2(PPh3)2(pip)] complex in the presence of norbornadiene (NBD) and the carbene source ethyl diazoacetate (EDA). Formation of a hexacoordinated intermediate [RuCl2(PPh3)2(pip)(NBD)] is favored in the first step, with NBD doubly coordinated to the [RuCl2(PPh3)2(pip)] moiety. Analysis of donation (X → Ru) and back-donation (Ru → X) processes in the [RuCl2(PPh3)2(pip)(NBD)] complex shows that piperidine behaves as a σ donor, while NBD behaves as a π donor and the PPh3 groups act as π acceptors. The intensity of the orbital component is predominant in relation to the steric component in the complex. Thus, we propose that the reaction occurs through the formation of a hexacoordinated complex, followed by the dissociation of a PPh3 group, thus forming a complex where NBD is doubly coordinated to the metal center. Coordination of EDA leads finally to the catalyst capable of forming the metallocyclobutane intermediate required for the ROMP reaction.

Latency for All: Enabling Latency of Hoveyda-Grubbs Second-Generation Catalysts by Adding Phosphite Ligands.

The Hoveyda-Grubbs catalyst (HG2, M720 Umicore) is among the most widely used catalysts in olefin metathesis reactions. Given the usefulness of HG2 and the great interest in developing latent olefin metathesis catalysts for numerous applications, we developed a method to introduce phosphite molecules as ancillary ligands into the precatalyst framework. This modification alters the geometry of the complex from an active trans-dichloro form to a latent cis-dichloro species. Most unusually, the ligands coordinate to HG2 only in solidified solutions (most likely due to entropic factors), providing latent catalysts that can be activated on demand by heat or light by regenerating the original HG2 catalyst. Of particular interest is the use of these latent catalysts in ring-opening metathesis polymerization (ROMP) reactions and 3D printing methods. Indeed, the novel complexes displayed the required latency toward ROMP monomers, even the most reactive dicyclopentadiene. Irradiation with 405 nm light readily results in the expedited formation of the desired polymers. This novel approach provides a general and straightforward way to access efficient and well-defined latent olefin metathesis catalysts.

Tuning the Latency by Anionic Ligand Exchange in Ruthenium Benzylidene Phosphite Complexes

Recently discovered cis-dichloro benzylidene phosphite complexes are latent catalysts at room temperature and exhibit exceptional thermal and photochemical activation behavior in olefin metathesis reactions. Most importantly, the study of these catalysts has allowed their introduction in efficient 3-D printing applications of ring-opening metathesis derived polymers and the control of chromatically orthogonal chemical processes. Moreover, their combination with plasmonic Au-nanoparticles has given rise to novel smart materials that are responsive to light. Given the importance of the ligand shell in the initiation and reactivity behavior of this family of complexes, we set out to investigate the effect of anionic ligand exchange. Thus, we report herein two new ruthenium benzylidene benzylphosphite complexes where the chloride anionic ligands have been replaced by bromide and iodide anions (cis-Ru-Phos-Br2 & cis-Ru-Phos-I2). The thermal and photochemical activations of these dormant catalysts in a variety of ring-closing and ring-opening metathesis polymerization (RCM and ROMP) reactions were thoroughly studied and compared with the previously known chloride precatalyst. Photochemical RCM studies provided similar results, especially in non-hindered reactions, with the UV-A wavelength being the best in all cases. On the other hand, the thermal activation profile exposed that the anionic ligand significantly affects reactivity. Notably, cis-Ru-Phos-I2 disclosed particularly impressive initiation efficiency compared to the other members of the family.

Reactivity of niobium(V) pentaalkoxide complexes: Ring-opening metathesis polymerization of norbornene

The ring-opening metathesis polymerization (ROMP) of cyclic olefins with niobium(V) pentaalkoxide catalysts was studied. In the presence of zinc, benzylidene dichloride, and chlorotrimethylsilane, in situ niobium species was formed and ROMP reaction proceeded. Among niobium pentaalkoxide group, Nb(OEt)5 achieved the smallest dispersity value of the polymer and provided trans selective polynorbornene. In this paper, we discussed the role of additives and expected how the polymer was synthesized with Nb(OEt)5/TMSCl/Zn/PhCHCl2 system. We also elucidated the intermediate using some measurement.

Thermo/β-cyclodextrin-responsive ferrocenyl hydrogels constructed by ROMP reaction

Hydrogels with stimuli-responsive behavior have been of great interest to researchers from many fields, such as biotechnology, drug delivery, and sensors, owing to their “smart” change in properties under external stimuli such as temperature, pH, pressure, redox, magnetic and electric fields. In this work, using the third generation Grubbs’ catalyst as the initiator, both temperature and β-cyclodextrin (β-CD) stimuli-responsive ferrocenyl hydrogels were prepared with different proportions of hydrophilic norbornene monomer NTEG, ferrocene-containing monomer NFc and crosslinker 1 by using one-pot ROMP (ring-opening metathesis polymerization) reaction. Based on the mechanical and rheological tests, it was found that NFc not only played a crucial role in maintaining the structure of ferrocenyl hydrogels, but also enhanced their physical strength. Comparatively, the increase of the NTEG content in the hydrogel system can improve the toughness of the resulting hydrogels. Furthermore, Results of the swelling ratio test demonstrated that these hydrogels possessed temperature-responsiveness, in which the NTEG block, which contained dendritic oligoethylene glycol structures in the side chain, played a decisive role. Simultaneously, it is worth noting that these ferrocenyl hydrogels also exhibited responsive behavior to β-CD solution due to the host-guest interaction of ferrocene unit with β-CD macromolecule. Therefore, we believe that this study provides a new idea for the design of covalently crosslinked ferrocenyl stimuli-responsive smart hydrogels.

Ring-Opening Metathesis Polymerization and Related Olefin Metathesis Reactions in Benzotrifluoride as an Environmentally Advantageous Medium

A tremendous number of solvents, either as liquids or vapors, contaminate the environment on a daily basis worldwide. Olefin metathesis, which has been widely used as high-yielding protocols for ring-opening metathesis polymerization (ROMP), ring-closing metathesis (RCM), and isomerization reactions, is typically performed in toxic and volatile solvents such as dichloromethane. In this study, the results of our systematic experiments with the Grubbs G1, G2, and Hoveyda-Grubbs HG2 catalysts proved that benzotrifluoride (BTF) can replace dichloromethane (DCM) in these reactions, providing high yields and similar or even higher reaction rates in certain cases. The ROMP of norbornene resulted not only in high yields but also in polynorbornenes with a high molecular weight at low catalyst loadings. Ring-closing metathesis (RCM) experiments proved that, with the exception of the G1 catalyst, RCM occurs with similar high efficiencies in BTF as in DCM. It was found that isomerization of (Z)-but-2-ene-1,4-diyl diacetate with the G2 and HG2 catalysts proceeds at significantly higher initial rates in BTF than in DCM, leading to rapid isomerization with high yields in a short time. Overall, BTF is a suitable solvent for olefin metathesis, such as polymer syntheses by ROMP and the ring-closing and isomerization reactions.

A Supramolecular Strategy for the Synthesis of Cyclic Oligomers and Polymers by Ring Expansion.

Ring-opening metathesis polymerization (ROMP) of strained macrocycles is a key method to prepare diverse polymers. However, lack of ring strain in most macrocycles is an impediment to polymerization. In this paper, the polymerization/oligomerization of unstrained macrocycles was achieved using a supramolecular approach, leading selectively to cyclic products. Diphenyl thiourea and other guest molecules were used as additives to the ROMP reaction of unstrained macrocycles. An intermediate host-guest complex leads to the stabilization of the open form of the macrocycle after treatment with Grubbs catalysts, thereby favoring polymerization by inhibiting the ring-closing reaction back to the monomer. This proof-of-concept enables ring-expansion polymerization of unstrained macrocycles leading to cyclic polymers with molecular weights up to 6700 Da.

Pseudopeptidic polymers for modulating electro-optic switching, dielectric and electrical properties of liquid crystal

Herein, we report the stabilization of a nematic liquid crystal using chiral amino acid-based polymers. For the first time, the effect of molecular weight of structurally similar polymers on the physical parameters of polymer-stabilized liquid crystals (PSLCs) is investigated. To obtain PSLCs, three pseudopeptidic bottlebrush polymers of different molecular weights are synthesized from the same monomer using a ring-opening metathesis polymerization (ROMP) reaction. The bottlebrush polymers form self-assembly networks in the LC matrix. The size of the self-assembled network is readily tunable by the systematic variation in the molecular weight of the constituent polymer. The polymer network assembly is characterized by using field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM). The ion density and diffusion coefficient of two different types of mobile ions are calculated by utilizing experimental dielectric data. The constituent polymer determines the structure of self-assembly network in PSLC and hence, the dielectric, electrical, electro-optic, and optical properties. The PSLCs show significant improvement in the response time (∼21%), dielectric anisotropy (∼40%), conductivity (∼11%), current (5-fold increment at 20 V), and phase transition temperature (PTT) upon variation in the molecular weight of the doped polymer units. This simple method of tuning response time, dielectric anisotropy, conductivity, current, and PTT using polymers of different molecular weights presents several possibilities of fabricating optoelectronic devices.

Solvent Effects in Grafting-through Ring-Opening Metathesis Polymerization

Ring-opening metathesis polymerization (ROMP) utilizing Grubbs’ third-generation catalyst ((H2IMes)(Cl)2(pyr)2RuCHPh) shows the characteristics of living polymerizations, including molecular weights increasing with monomer conversion and the ability to make (multi)block copolymers. However, irreversible termination reactions still occur due to catalyst decomposition, leading to terminated chains, especially in the context of sterically demanding monomers such as macromonomers (MMs). In this work, we performed identical ROMP reactions on three different MMs in six solvents commonly used in ROMP with varying levels of purity. The solvents included ethyl acetate (EtOAc), dichloromethane (CH2Cl2), chloroform (CHCl3), toluene, tetrahydrofuran (THF), and N,N-dimethylformamide (DMF). All polymerizations were conducted under air targeting a bottlebrush polymer backbone degree of polymerization (Nbb) of 100. All three MMs included a norbornene on the α chain end and had a molecular weight (Mn) of ∼4 kg/mol. They included one polystyrene MM with a bromine on the ω chain end and two poly(n-butyl acrylate) MMs with either a bromine or a trithiocarbonate group on the ω chain end. Solvent choice, and in some cases the level of purity, led to significant differences in the propagation rate in these ROMP grafting-through reactions. Of the solvents tested, the propagation rates in EtOAc and CH2Cl2 were approximately 4-fold and 2-fold faster, respectively, than that in CHCl3, toluene, and THF for all MMs. Propagation was much slower in DMF for the polystyrene MM than all the other solvents and on par with the slower solvents for the two poly(n-butyl acrylate) MMs tested. The purity of the solvent in some cases had a profound effect on the propagation rate: In the case of EtOAc, purification led to a 2-fold decrease in propagation rate; in contrast, purification of THF was required to observe full conversion of a MM to a bottlebrush polymer. The functional group on the ω chain end did not influence the rate of ROMP. Utilizing UV–vis spectroscopy to measure catalyst decomposition, the main polymer termination route in ROMP, we uncovered dramatic solvent effects, where the catalyst decomposed over 10 times faster in THF and DMF than in toluene. Finally, studies targeting Nbb = 500 or 1000 revealed that toluene, EtOAc, and CH2Cl2 demonstrated the highest degree of “livingness” in ROMP. These results will enable the synthesis of complex polymer architectures using ROMP with a high degree of living character.

Monometallic and heterobimetallic ruthenium (II) and palladium (II) complexes based on a pyridine‐hydrazone ligand as bifunctional catalysts for ROMP of norbornene and ethylene polymerization

AbstractThe monometallic complex [Pd(L)(PPh3)] (mono‐Pd) was synthesized using a potentially tridentate hydrazone (H2L) and used as precursor to prepare a heterobimetallic ruthenium (II)‐palladium (II) complex [Cl2(p‐cymene)Ru(μ‐L)Pd (PPh3)] (Ru‐Pd). Mono‐Pd and Ru‐Pd were characterized by fourier transform infrared spectroscopy (FTIR), ultraviolet‐visible spectroscopy (UV–Vis), 1H, 13C{1H} and 31P{1H} nuclear magnetic ressonance(NMR) spectroscopy, elemental analysis, cyclic voltammetry, matrix‐assisted laser desorption/ionization ‐ time of flight (MALDI‐TOF) mass spectrometry, and computational methods. The mono‐Pd was additionally studied by single‐crystal X‐ray diffraction. The complex [RuCl2(p‐cymene)(Isoniazid)] (mono‐Ru) was also obtained following literature methods aiming a comparison in the catalytic activity. The ring opening metathesis polymerization (ROMP) of norbornene (NBE) using mono‐Ru or Ru‐Pd as precatalysts in the presence of ethyl diazoacetate (EDA) was evaluated as a function of time (10–60 min) using [NBE]/[EDA]/[Ru] = 5000/28/1 at 50°C. The time increases produced good yields of polyNBE, reaching 38% and 46% for mono‐Ru and Ru‐Pd, respectively. The polyNBE produced was measured by size‐exclusion chromatography (SEC) and reached an order of magnitude of 105 g·mol−1 of Mn, with Ð values ranging from 2.51 to 1.86 for mono‐Ru and from 3.50 to 1.66 for Ru‐Pd. The catalytic activity of mono‐Pd and Ru‐Pd on ethylene polymerization was assessed with a range of [Al]/[Pd] molar ratio between 350 and 1750, 30–70°C temperature, 2 to 4 h reaction time, and total reaction volume of 25 and 50 ml. Mono‐Pd achieved an activity of 22.80 kg PE (mol Pd)−1 h−1 at 60°C after 4 h using [Al]/[Pd] = 1050, 7 μmol of catalyst in 25 ml of toluene, and 116 psi ethylene. For Ru‐Pd, an activity of 20.35 kg PE (mol Pd)−1 h−1 at 60°C after 4 h was obtained using [Al]/[Pd] = 1750, 7 μmol of catalyst in 25 ml of toluene, and 116 psi ethylene. Overall, Ru‐Pd showed to be active in both ROMP and ethylene polymerization reactions, being categorized as a bifunctional catalyst.

Substituent Effects Provide Access to Tetrasubstituted Ring-Opening Olefin Metathesis of Bicyclo[4.2.0]oct-6-enes.

Herein, we report the origin of unexpected reactivity of bicyclo[4.2.0]oct-6-ene substrates containing an α,β-unsaturated amide moiety in ruthenium-catalyzed alternating ring-opening metathesis polymerization reactions. Specifically, compared with control substrates bearing an ester, alkyl ketone, nitrile, or tertiary amide substituent, α,β-unsaturated substrates with a weakly acidic proton showed increased rates of ring-opening metathesis mediated by Grubbs-type ruthenium catalysts. 1H NMR and IR spectral analyses indicated that deprotonation of the α,β-unsaturated amide substrates resulted in stronger coordination of the carbonyl group to the ruthenium metal center. Principal component analysis identified ring strain and the electron density on the carbonyl oxygen (based on structures optimized by means of ωB97X-D/6311+G(2df,2p) calculations) as the two key contributors to fast ring-opening metathesis of the bicyclo[4.2.0]oct-6-enes; whereas the dipole moment, conjugation, and energy of the highest occupied molecular orbital had little to no effect on the reaction rate. We conclude that alternating ring-opening metathesis polymerization reactions of bicyclo[4.2.0]oct-6-enes with unstrained cycloalkenes require an ionizable proton for efficient generation of alternating polymers.

Ring Opening Metathesis Polymerization of a New Monomer Derived from a Nitroso Diels–Alder Reaction

AbstractA nitroso Diels–Alder (NDA) reaction between cyclopentadiene and an in situ generated nitroso compound leads to a new heterocyclic monomer for ring opening metathesis polymerization (ROMP) reactions. This monomer could be polymerized in the presence of Grubbs‐third generation initiator with good control over Mn and decent Ð values. The resulting isoxazolidine‐containing material could undergo further hydrogenation, deprotection, and modification with Dansyl chloride as well as ring opening to provide an amino‐and hydroxyl‐decorated “polyolefin.”

Recent Developments in Z‐Selective Olefin Metathesis Reactions by Molybdenum, Tungsten, Ruthenium, and Vanadium Catalysts

AbstractThis review article summarizes reports for Z‐selective olefin metathesis reactions by molybdenum, tungsten, ruthenium, and vanadium catalysts. It is clearly demonstrated that the ligand modifications play essential roles in achieving the stereospecific olefin metathesis reactions. In particular, Mo‐ and W‐alkylidene based complex catalysts having pyrrolide‐aryloxide [or bis(aryloxide)] were highly effective in the efficient enantioselective ring opening/cross‐metathesis (EROCM), cross metathesis (CM), homodimerization, ring‐opening metathesis polymerization (ROMP), and in ring closing metathesis (RCM) with high Z‐ selectivities (∼>98%). Ruthenium‐carbene catalysts having cycloadamantyl, catechothiolate, phenolate and thiophenolate ligands display pronounced Z‐selectivity (>98%) in efficient CM, ROCM, AROCM, RCM, ROMP reactions. Halogenated (arylimido)‐alkoxo vanadium‐alkylidenes were thermally robust and effective for efficient highly cis‐specific ROMP of cyclic olefins to afford end‐functionalized ring‐opened polymers.magnified image

Failure analysis of self-healing epoxy resins using microencapsulated 5E2N and carbon nanotubes

Investigation on self-healing properties of epoxy containing microcapsules of pure 5-ethylidene-2-norbornene (5E2N) and mixed multi-walled carbon nanotube (MWCNT) suspension is presented in this work using lap shear and mode I fracture tests. While both systems show significant self-healing functionalities between 39% and 97%, those repaired with MWCNT/5E2N microcapsules are found to have mechanical recovery efficiencies two times higher than those containing 5E2N alone, under different types of loading. MWCNT/5E2N microcapsules are also found to improve the physical strength of the epoxy matrix much higher than microcapsules containing only 5E2N. Compared to self-healing epoxy systems made of 5E2N microvessels, the dispersion of 0.10 wt.% of only MWCNTs inside the encapsulated monomer increases the lap shear strengths of the pristine materials and the self-healing materials tested after one fracture/curing cycle, by about 50% and 250%, respectively. Using fractographic observations, Raman spectroscopy and scanning electron microscopy, we observe the occurrence of a ring opening metathesis polymerization reaction and the contribution of MWCNTs to strengthening the material. The present work indicates that the MWCNT/5E2N microcapsule when incorporated into an appropriate epoxy formulation can serve as efficient self-healing matrix material for laminated composites, as well as self-healing structural adhesives for composite bonded joints, two features that make this system highly relevant for applications in aerospace engineering.

Synthesis of hyaluronated poly(exo-7-oxabicyclo[2.2.1]hept-5-en-2,3-dicarboxylic anhydride) brushes via a combination of surface-initiated ring-opening metathesis polymerization and thiol-ene click reaction

Well-defined hyaluronated poly(exo-7-oxabicyclo[2.2.1]hept-5-en-2,3-dicarboxylic anhydride) [poly(EHDA)-HA] brushes on the hydroxyl-terminated silicon (Si–OH) surface were prepared through the combination of surface-initiated ring-opening metathesis polymerization (ROMP) and thiol-ene click reaction. This process was realized in four successive steps: (i) formation of self-assembled monolayer of (3-aminopropyl) triethoxysilane on the Si–OH surface (Si-APTES), (ii) bonding of EHDA monomer to the Si-APTES surface, (iii) synthesis of poly(EHDA) brushes via surface-initiated ROMP and (iv) coupling of thiolated hyaluronic acid (Th-HA) to poly(EHDA) chains via thiol-ene click reaction. Surface wettability, surface morphology and chemical compositions of poly(EHDA)-HA brushes were characterized by contact angle measurements, atomic force, microscopy and X-ray photoelectron spectroscopy, respectively. Grafting density (σ, chains nm−2) and average distance between grafting points (D, nm) of the poly(EHDA) brushes were measured to be 0.50 chains nm−2 and 1.65 nm, independent of the [catalyst]/[monomer] ratios, which indicated that high grafting was created on the silicon substrate. However, low amounts of HA molecules were bonded to poly(EHDA) chains due to the high volume of Th-HA chains creating some steric hindrances. Biocompatible property of the poly(EHDA)-HA brushes are useful candidate for making advanced biological devices to control the behavior of biomolecules on surfaces.

The effect of grafting density and side chain length on the conformation of PEG grafted bottlebrush polymers

PEG grafted polymers are a kind of promising materials, and widely applied in polymer electrolytes, lubricants, biotechnology and biomedical science. While up to now, systematical researches of the relationship between architecture and conformation of PEG grafted polymers are very rare. Here, we efficiently and successfully prepared a series of PEG grafted polymers with different grafting density, and side chain length by combining ring-opening metathesis polymerization (ROMP) and Copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, and then characterized the conformations of the synthesized bottlebrush polymers by AFM technique. The AFM images showed that all the polymers P(NB-alkyne)400-g-PEG with low grafting density were spherical morphology, while the polymers P(NB-2alkyne)400-g-PEG and P(NB-4alkyne)394-g-PEG presented cylindrical morphology, which indicated that only grafting density could determine the shape of the prepared PNB-g-PEG bottlebrush polymers. While, the side chain length could affect the size of prepared PEG grafted bottlebrush polymers.

ROMP of supramolecular norbornene monomers containing β-cyclodextrin–ferrocene (/adamantane) inclusion complexes

Through the use of N-[2′-ferrocenylformamido-ethyl]-cis-5-norbornene-exo-2,3-dicarboximide (NFc) and N-[2′-adamantylformamido-ethyl]-cis-5-norbornene-exo-2,3-dicarboximide (NAd), we report the fabrication of two novel supramolecular norbornene monomers, NFc@β-CD and NAd@β-CD, through β-cyclodextrin (β-CD)/ferrrocene(Fc)- and β-CD/adamantane (Ad)-based host–guest complexation. The formation and structure of the two monomers were verified by various techniques, such as 1H and 13C NMR, 2D NOESY, IR and UV–vis spectroscopic methods. The ROMP (ring-opening metathesis polymerization) feasibility of the two supramolecular monomers was further confirmed by the successful preparation of two homopolymers (P(NFc@β-CD) and P(NAd@β-CD)) and two diblock copolymers (PNFc-b-P(NAd@β-CD) and P(NFc@β-CD)-b-P(NAd@β-CD)). The prepared polymers were adequately analyzed using 1H and 13C NMR, IR, UV–vis, end-group analysis and GPC methods. Based on the obtained results, we believe that (1) both supramolecular monomers exhibited “living” and “controlled” ROMP reactions; (2) the β-CD/Fc and β-CD/Ad inclusion complexes were not disassembled during the ROMP reactions of the two supramolecular monomers; and (3) the functional groups of β-CD had a negligible effect on the catalytic activity of the third-generation Grubbs’ catalyst. In short, this work indicated that the direct ROMP of β-CD-containing supramolecular monomers was a feasible route for preparing supramolecular polynorbornene-based homopolymers and copolymers, and this route is expected to have great potential for the preparation of various supramolecular polynorbornenes and functional materials. Two novel supramolecular norbornene monomers were prepared according to β-cyclodextrin–ferrocene (/adamantane) host–guest interactions and exhibited both the “living” and “controlled” ROMP characteristics with the aid of the third-generation Grubbs’ catalyst for the construction of corresponding supramolecular homopolymers and diblock copolymers.

Polynorbornene‐g‐poly(ethylene oxide) Through the Combination of ROMP and Nitroxide Radical Coupling Reactions

ABSTRACTGrafting‐onto and grafting‐through strategies for preparing polynorbornene‐g‐poly(ethylene oxide)s (PNB‐g‐PEO) have been developed through a combination of ring‐opening metathesis polymerization (ROMP) and nitroxide radical coupling (NRC). 2‐Bromoisobutyrate‐functionalized poly(ethylene oxide) monomethyl ether 2000 (PEO45‐Br) was successfully anchored on a 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO)‐containing polynorbornene backbone of number‐average degree of polymerization () of 100 through the grafting‐onto strategy, resulting in PNB‐g‐PEO with a grafting yield ranging up to 90%. ROMP of ω‐exo‐norbornenyl PEO45 monomethyl ether macromonomer issued from NRC between a nitroxide‐functionalized norbornene and PEO45‐Br has allowed to reach a well‐defined bottlebrush copolymer with a backbone of 100 while retaining a low dispersity of 1.09. The effect of the grafting‐onto versus grafting‐through strategy and, consequently, of the grafting density, was investigated by thermal analyses and self‐assembly properties of the PNB100‐g‐PEO45. A substantial reduction of crystallinity was observed for PNB‐g‐PEO prepared via the grafting‐through route. Preliminary study of the self‐assembling properties has shown that the graft copolymers form monodisperse spherical particles in aqueous solution. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 645–653

Correction: Flow-facilitated ring opening metathesis polymerization (ROMP) and post-polymerization modification reactions

Correction for ‘Flow-facilitated ring opening metathesis polymerization (ROMP) and post-polymerization modification reactions’ by Selesha I. Subnaik et al., Polym. Chem., 2019, 10, 4524–4528, DOI: 10.1039/C9PY00822E