Polymerization Of Norbornene Research Articles

Reactivity of the p‐Cymene‐Ru Complex with Two Phenylamines for Metathesis Polymerization of Norbornene Compared to the Reactivity of Complexes with a Single Benzylamine or Dibenzylamine

Reactivity of the p‐Cymene‐Ru Complex with Two Phenylamines for Metathesis Polymerization of Norbornene Compared to the Reactivity of Complexes with a Single Benzylamine or Dibenzylamine

Polymerization of Ester-Functionalized Norbornenes Using Neutral Nickel Catalysts

Polymerization of Ester-Functionalized Norbornenes Using Neutral Nickel Catalysts

New Catalyst Systems for the Polymerization of Norbornene and Its Derivatives Based on Cationic Palladium Cyclopentadienyl Complexes

The catalytic properties of systems based on [Pd(Cp)(L)n]m[BF₄]m (where Cp = η5-C5H5; n = 2, m = 1: L = tris(orthomethoxyphenyl)phosphine, triphenylphosphine, tris(2-furyl)phosphine (TFP), n = 1, m = 1: L = 1,1'-bis(diphenylphosphino)ferrocene, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: L = 1,6-bis(diphenylphosphino)hexane) in the addition homoand copolymerization of norbornene (NB) and its derivatives have been studied. These complexes can be activated with the Lewis-acids (BF₃ ∙ OEt2 or AlCl3). The productivity of the [Pd(Cp)(PPh3)2][BF₄]/BF₃ ∙ OEt2 catalyst system in the polymerization of norbornene is up to 188800 molNB molPd⁻¹. The homopolymerization of 5-methoxycarbonylnorbornene and copolymerization of NB with 5-methoxycarbonylnorbornene or 5-phenylnorbornene were studied in the presence of BF₃ ∙ OEt2 and [Pd(Cp)(L)2][BF₄] (L = PPh3 or TFP). A hypothesis for the catalyst’s formation via the intramolecular rearrangement of the η5-Cp ligand into the η1-Cp form upon interaction with a Lewis acid is suggested. The structure of the [Pd(Cp)(TFP)2]BF₄ (I) was determined by X-ray diffraction. In the crystal structure of I, the palladium coordination sphere is characterized by a slight distortion of the square planar geometry of the central atom, and the cyclopentadiyl fragment is in an eclipsed conformation. Based on the XRD data, the steric hindrance of the TFP ligand was estimated (the cone angle is 149°).

Synthesis and Characterization of Dearomatized Pyridine‐Derived Alkyl‐Amido‐tert‐Butylphosphine Iron(II) Complexes

AbstractNeutral three‐coordinate iron alkylidenes of the form PN−Fe=CHR have been proposed as viable candidates for alkene metathesis. Indeed, during the final stages of preparing this current study, a separate report disclosed that dearomatized PN−Fe‐alkyl complexes are active precatalysts for ring‐opening metathesis polymerization (ROMP) of norbornene implicating PN−Fe=CHR species as possible intermediates. In yet another separate report, we prepared Zn analogues of PN−Fe‐alkyl complexes and herein provide an account for the synthesis, characterization, and reactivity of some new iron complexes with the same tBu substituted PN platform.

Novel Catalyst Systems Based on Cationic Palladium Cyclopentadienyl Complexes for the Polymerization of Norbornene and Norbornene Derivatives

Novel Catalyst Systems Based on Cationic Palladium Cyclopentadienyl Complexes for the Polymerization of Norbornene and Norbornene Derivatives

Applications of metal N-heterocyclic carbene complexes in olefin polymerizations

This review summarizes the progress in recent decades regarding the structure–activity relationships of various well-defined metal-NHC catalysts in the polymerization of olefins, particularly α-olefins, styrene, norbornene, and others.

Single‐Component Catalysts for the Vinyl‐Addition Polymerization of Norbornene and its Derivatives

AbstractVinyl‐addition polynorbornenes are versatile templates for the targeted design of high‐performance materials for various applications such as membrane gas separation, micro‐ and optoelectronics, fuel cells, sensors, and catalyst supports. The cornerstone of the synthesis of these compounds is the choice of catalyst used for polymerization. Previous review articles focused on two‐ and three‐component catalytic systems with cocatalysts used for vinyl‐addition polymerization (VAP). Hence, this Review discusses the advances in the design and development of single‐component neutral and cationic catalysts for the VAP of norbornenes. The catalyst structure, catalytic activity, and molecular weight characteristics of the polymers produced using these catalysts are elucidated.

Vinyl-Addition Homopolymeization of Norbornenes with Bromoalkyl Groups.

Vinyl-addition polynorbornenes are of great interest as versatile templates for the targeted design of polymer materials with desired properties. These polymers possess rigid and saturated backbones, which provide them with high thermal and chemical stability as well as high glass transition temperatures. Vinyl-addition polymers from norbornenes with bromoalkyl groups are widely used as precursors of anion exchange membranes; however, high-molecular-weight homopolymers from such monomers are often difficult to prepare. Herein, we report the systematic study of vinyl-addition polymerization of norbornenes with various bromoalkyl groups on Pd-catalysts bearing N-heterocyclic carbene ligands ((NHC)Pd-systems). Norbornenes with different lengths of hydrocarbon linker (one, two, and four CH2 groups) between the bicyclic norbornene moiety and the bromine atom were used as model monomers, while single- and three-component (NHC)Pd-systems were applied as catalysts. In vinyl-addition polymerization, the reactivity of the investigated monomers varied substantially. The relative reactivity of these monomers was assessed in copolymerization experiments, which showed that the closer the bromine is to the norbornene double-bond, the lower the monomer's reactivity. The most reactive monomer was the norbornene derivative with the largest substituent (with the longest linker). Tuning the catalyst's nature and the conditions of polymerization, we succeeded in synthesizing high-molecular-weight homopolymers from norbornenes with bromoalkyl groups (Mn up to 1.4 × 106). The basic physico-chemical properties of the prepared polymers were studied and considered together with the results of vinyl-addition polymerization.

ONE-POT SYNTHESIS OF NORBORNENE-CYCLOOCTENE COPOLYMERS

The one-pot synthesis of random multiblock copolymers of norbornene and cyclooctene has been performed for the first time. It is shown that the first generation Grubbs Ru-carbene complex makes it possible to obtain these copolymers directly from monomers. In the course of one-pot synthesis, the metathesis polymerization of norbornene, which has a markedly higher ring strain, occurs first. Then, cyclooctene polymerizes and simultaneously an interchain cross-metathesis reaction takes place, during which the block structure of the copolymer is formed. Compared to the previously studied interaction of polynorbornene and polycyclooctene, the one-pot method makes it possible to obtain copolymers with a higher molar mass at a lower catalyst consumption.

(Arylimido)niobium(V)–Alkylidenes as the Catalysts for Ring-Opening Metathesis Polymerization (ROMP) of Cyclic Olefins: Z-Specific ROMP of Cyclooctene by Nb(CHSiMe3)(NC6H5)[OC(CF3)3](PMe3)2

(Arylimido)niobium(V)–alkylidene complexes, Nb(CHSiMe3)(NAr)[OC(CF3)3](PMe3)2 (Ar = C6H5 (4), 2,6-F2C6H3, C6F5 (6)), Nb(CHSiMe3)(N-2,6-Cl2C6H3)(OC6F5)(PMe3)2 (7), and Nb(CHSiMe3)(N-2,6-F2C6H3)(OC6Cl5)(PMe3)2, have been prepared and identified. The pentafluorophenylimido analogue 6 and 7 showed superior catalytic activities for the ring-opening metathesis polymerization (ROMP) of norbornene (TOF = 56.1, 53.7 s–1, respectively, at 25 °C) and the activities increased at 50 °C (TOF ≥ 352 s–1). The prepared alkylidenes catalyzed the ROMP of cis-cyclooctene (COE), and the activity increased at high temperature (up to 80 °C). The Z-specific ROMP of COE has been demonstrated especially by the phenylimido analogue 4 at 80 °C, affording polymers possessing olefinic double bonds with exclusive cis selectivity (99%).

Cationic palladium(II)–acetylacetonate complexes bearing pyridinyl imine ligands as catalysts for the hydroamination of phenylacetylene and polymerization of norbornene

Acetylacetonate palladium(II) complexes bearing pyridinyl imine ligands [Pd(acac)(L)]BF4 were synthesized via nitrile displacement in [Pd(acac)(MeCN)2]BF4 by the bidentate ligands L of type 2-C5H4N–CH=N–(CH2)nOMe or 2-C5H4N–CH=N–Ar. The structures of complexes were analyzed by X-ray diffractometry, NMR, and DFT. The complexes catalyze hydroamination of phenylacetylene with aniline to give the Markovnikov imine product as well as polymerization of norbornene.

Rational design of aldimine imidazolidin-2-imine/guanidine nickel catalysts for norbornene (Co)polymerizations with enhanced catalytic performance

The development of late transition metal catalysts bearing novel ligand platforms is a convenient pathway to obtain prospective systems with enhanced catalytic performance, however, it remains a challenge in the field of olefin (co)polymerizations. In this contribution, a new family of [N,N]-type of bidentate aldimine imidazolidin-2-imine/guanidine ligands and their nickel complexes Ni1–Ni7 bearing a distinct six-membered chelate ring were successfully synthesized, and characterized. All of the nickel catalysts were active for norbornene polymerization with high activity of up to 7.44 × 105 g mol–1 h−1. These catalysts also copolymerized norbornene and 1-alkenes (1-dodecene and 1-octadecene) while keeping high activities to produce various norbornene-based high-molecular-weight (Mn = 5.75–36.0 kg mol−1) cyclic olefin copolymers (COCs) with adjustable 1-alkene incorporations (1.44–13.30 mol%) and a wide range of Tg values (102.2–271.4 °C). Moreover, with the decoration of bulky N-aryl substituents, these nickel catalysts exhibited strong tolerance towards polar monomer to promote the direct copolymerization of norbornene and methyl 10-undecenoate with high activity (up to 9.88 × 104 g mol–1 h−1), and furnished polar functionalized COCs with a high molecular weight (Mn up to 72.4 kg mol−1) and reasonable polar monomer incorporations (0.19–0.45 mol%). These nickel complexes are rare examples and also promising candidates as catalysts for the efficient synthesis of various COCs.

Copolymerization of Norbornene and Methyl Acrylate by Nickel Catalyst Bearing 2-(Diarylphosphino)-N-phenylbenzenamine Ligands

The synthesis of polar functionalized cyclic olefin copolymers (COCs) from the coordination copolymerization of norbornene (NB) and polar monomers catalyzed by late transition metal catalysts has been a recent research hotspot. However, few catalysts have achieved efficient copolymerization with commercial vinyl-type polar monomers, such as methyl acrylate (MA). In this contribution, nickel complexes bearing 2-(diarylphosphino)-N-phenylbenzenamine ligands were synthesized and applied as pre-catalysts to catalyze the (co)polymerization of norbornene. Upon the activation of methylaluminoxane (MAO), these nickel catalysts were active for norbornene polymerization with the highest activity achieved being 3.6 × 106 g mol−1 h−1 and the highest number average molecular weight (Mn) of polynorbornene (PNB) reaching 27.4 × 105 g mol−1. Moreover, these nickel catalysts also promoted the copolymerization of norbornene and MA to furnish high-molecular-weight NB/MA copolymers (Mn up to 6.20 × 104 g mol−1) with reasonable MA contents (3.07−5.90 mol%). The molecular weight of PNB and NB/MA copolymers obtained by the present nickel catalysts are remarkably higher than those of the (co)polymers from our previous reported dimethyl substituted phosphinobenzenamine nickel catalyst, suggesting significant progress in this field.

Norbornene polymerization and copolymerization with ethylene by titanium complexes bearing pyridinium imide ligand

Norbornene polymerization and copolymerization with ethylene by titanium complexes bearing pyridinium imide ligand

Ni(acac)2 Mediated Vinyl Polymerization of Norbornene in the Presence of Bulky Salicylaldiminate Ligands: An Effective Strategy to Access Soluble Polynorbornenes

Ni(acac)2 Mediated Vinyl Polymerization of Norbornene in the Presence of Bulky Salicylaldiminate Ligands: An Effective Strategy to Access Soluble Polynorbornenes

Ru/Pd Complex and Its Monometallic Fragments as Catalysts for Norbornene Polymerization via ROMP and Addition

The [Ru(PPh3)2Cl-piperidine(4-aminomethyl)] complex (mono-Ru) was synthesized from [Ru(PPh3)3Cl2] and 4-(aminomethyl)piperidine, whereas the [(PPh3)PdCl(Shiff-pip)] complex (mono-Pd) was obtained by reacting [Pd(PPh3)2Cl2] with its respective Schiff base ligand, both at a 1:1 molar ratio. The heterobimetallic [RuCl2(PPh3)2](μ-Schiff)Pd(PPh3)Cl] complex (Ru/Pd) was synthesized via a one-pot, three-component reaction of mono-Ru, [(Pd(PPh3)2Cl2] and salicylaldehyde. All complexes were fully characterized by FTIR, UV-Vis, and NMR spectroscopy, as well as elemental analysis, MALDI-TOF mass spectrometry, cyclic voltammetry, and computational studies. Ru/Pd was able to polymerize norbornene (NBE) by two different mechanisms: ROMP and vinyl polymerization. The Ru fragment was active for ROMP of NBE, reaching yields of 68 and 31% for mono-Ru and Ru/Pd, respectively, when the [NBE]/[Ru] = 3000 molar ratio and 5 μL EDA addition were employed at 50 °C. The poly(norbornene) (polyNBE) obtained presented an order of magnitude of 104 g mol−1 and Ð values between 1.48 and 1.79. For the vinyl polymerization of NBE, the Pd fragment was active using MAO as a cocatalyst, reaching a yield of 47.0% for Ru/Pd and quantitative yields for mono-Pd when [Al]/[Pd] = 2500 and [NBE]/[Pd] = 20,000 molar ratios were employed, both at 60 °C.

Synthesis and Characterization of Core‐Shell Bottlebrush Polymers via Controllable Polymerization

AbstractThis research was focused on the synthesis of well‐defined bottlebrush polymers (BBPs) comprising of polynorbornene (PNB) backbones and side‐chains of the polylactide (PLA)‐b‐polystyrene (PS). The PNB backbones were synthesized via ring‐opening metathesis polymerization of norbornene, and then L‐lactide (LA) was first grafted to the backbones to form PLA side‐chains by ring‐opening polymerization. Afterwards, styrene was further grafted to the PLA cantilever with triothiocarbonate modification via reversible addition‐fragmentation chain transfer polymerization to form PLA‐b‐PS side‐chains. Controllable polymerization was achieved by introducing each block in stages. A novel structure with PLA and PS block arranged in tandem was constructed, and their morphologies of self‐assembly in bulk were investigated by transmission electron microscopy imaging. The results demonstrated that the compositions and molecular weight of the side‐chains in the BBPs affected the self‐assembling morphologies of the BBPs significantly, and revealed that the polymers were with core‐shell structures.

Vinyl-addition polymerizations of norbornene and methyl methacrylate by the palladium(II) complexes ligated by 2-iminomethylquinoline and 2-iminomethylpyridine derivatives

Novel Pd(II) complexes, namely, [LnPdCl2] (Ln = LA and LB), where LA is (E)-3-methoxy-N-(quinolin-2-ylmethylene)propan-1-amine and LB is (E)-N-(pyridin-2-ylmethylene)hexan-1-amine, were synthesized and characterized. X-ray diffraction studies revealed distorted square planar geometries around the Pd(II) center in [LnPdCl2] (Ln = LA and LB). The catalytic capabilities of the synthesized complexes were tested in vinyl addition polymerization of norbornene (NB) in the presence of the cocatalyst modified methylaluminoxane (MMAO), displaying high activities with conversions ≥ 94% in chlorobenzene at 25 °C. The complex [LBPdCl2] displayed the highest activity of up to 4.40 × 106 gPNBmolPd−1h−1 at 25 °C, generating insoluble polynorbornene (PNB) at an NB/Al/Pd ratio of 8,000:500:1. In addition, preliminary methyl methacrylate (MMA) polymerization studies of the [LnPdCl2]/MMAO system demonstrated that the activities toward polar vinyl monomer production were in the range of 8.00 × 104 to 8.20 × 104gPMMAmolPd−1h−1 at 60 °C, yielding a high-molecular-weight syndiotactic poly(methyl methacrylate) (PMMA, Mw = 1.89 × 106gmol−1).

Norbornene and methyl methacrylate polymerizations catalyzed by palladium(II) complexes bearing aminomethylpyridine and aminomethylquinoline derivatives

A series of Pd(II) complexes, 1–4 bearing N,N-bidentate aminomethylpyridine and aminomethylquinoline derivatives were synthesized and characterized. Single crystal X-ray diffraction analysis demonstrated that tetra-coordinated Pd(II) complexes adopted distorted square planar geometries around the metal center. In the presence of modified methylaluminoxane (MMAO) as a co-catalyst, Pd(II) complexes 1–4 exhibited significant activities (up to 43.2×105 gPNB mol Pd−1 h−1) towards the addition polymerization of norbornene (NB) at 25 ℃. Insoluble poly(norbornene) (PNB) was obtained by all the tested catalytic systems, i.e., 1–4/MMAO. The catalytic capabilities of synthesized Pd(II) complexes were also tested towards methyl methacrylate (MMA) in the presence of modified methyl aluminoxane MMAO. Complex 3 with quinoline/piperidine functionalities showed the highest catalytic activity of 8.83×104 gPMMA mol Pd−1 h−1 at 60°C and resulted in high molecular weight PMMA (Mw = 2.16×106 g mol−1). All the complexes yielded syndiotactic poly(methyl methacrylate) (PMMA) (rr = 0.70). Notably, the steric bulk and electronic properties of the ligand framework affect their activities towards NB and MMA polymerizations, whereas, for PMMA, the stereoselectivities remained unaffected.

Thermal‐stable asymmetric α‐diimine nickel(II) catalysts: Synthesis, characterization, and its norbornene (co)polymerization behavior

Four asymmetric α‐diimine dibromide nickel(II) complexes bearing both 2,6‐diisopropyl phenyl and substituted triphenyl {[(C3H7)2C6H3NC(C10H6)CN(R2C6H3)2C6H3]NiBr2, R = CH3,Catal.1; CF3,Catal.2; OCH3,Catal.3; C6H5,Catal.4} were synthesized and characterized. In the presence of B(C6F5)3, these newly synthesized nickel complexes showed high activities toward norbornene (NBE) homopolymerization (0.84–4.88 × 105 gpolymer/molNi‧h) under elevated temperatures, yielding high molecular weight polymers (106.5–657.9 kDa). These Ni/B catalytic systems also efficiently promoted the copolymerization of NBE withn‐butyl methacrylate (n‐BMA) and di(n‐butyl) itaconate (n‐DBI) under 70°C, respectively, affording copolymers with high molecular weight (n‐BMA: 95.0–235 kDa;n‐DBI:35.4–52.5 kDa) and moderate polar monomer incorporations (n‐BMA:1.2–6.4 mol%;n‐DBI:0.8–2.8 mol%). The copolymers with polar groups showed improved solubilities. The unimodal molecular weight distribution of the resultant polymers implied the single‐site catalytic behavior of these nickel catalysts toward NBE (co)polymerization. In addition, both the obtained PNB and the copolymers showed high glass transition temperature (289–345°C) and excellent thermal stability.