Showing papers on "Norbornene published in 2003"

Addition Polymerization of Norbornene-Type Monomers Using Neutral Nickel Complexes Containing Fluorinated Aryl Ligands

Abstract: The strong Lewis acid B(C6F5)3 was found to activate complexes of nickel toward the polymerization of norbornene-type monomers. The active species in this reaction is created by the transfer of C6F5 from boron to nickel. As a result, a class of neutral, single-component nickel complexes was developed containing two electron-withdrawing aryl ligands that polymerize norbornene and norbornenes with functional pendant groups. Active complexes include Ni(C6F5)2(PPh2CH2C(O)Ph), (η6-toluene)Ni(C6F5)2, and Ni(2,4,6-tris(trifluoromethyl)phenyl)2(1,2-dimethoxyethane). In the case of (η6-toluene)Ni(C6F5)2, isolation and characterization of low molecular weight norbornene polymers, using ethylene, indicated that each polymer chain contained a C6F5 headgroup. This points to the initiation step as being the insertion of norbornene into the Ni−C6F5 bond. The polymer microstructure as revealed by 1H and 13C NMR spectrometry is entirely different from that produced using the cationic nickel catalyst, [(η3-crotyl)Ni(1,4-CO...

Living ROMP of exo-Norbornene Esters Possessing PdII SCS Pincer Complexes or Diaminopyridines

Abstract: Isomerically pure exo-norbornene esters containing either a PdII SCS pincer complex or a diaminopyridine unit were synthesized, polymerized, and copolymerized by ring-opening metathesis polymerization using a ruthenium initiator. All polymerizations are living under mild reaction conditions. A comparison between the pure exo monomers and the commonly employed 80:20 endo/exo mixtures was carried out. The exo-norbornene isomers exhibit significantly higher rates of propagation under milder conditions when compared to the endo/exo mixtures. Kinetic studies have shown that the kp values are highly dependent upon the isomeric purity but completely independent of the terminal diaminopyridine or PdII SCS Pincer functional groups. The living character of the polymerization has allowed for the first block copolymerization of norbornene metal-containing pincer complexes and diaminopyridine-based hydrogen-bonding receptors.

Aerobic oxidations catalyzed by chromium corroles.

Abstract: Oxochromium(V) complexes of 5,10,15-tris(pentafluorophenyl)corrole and brominated derivatives oxygenate substrates (triphenylphosphine and norbornene) with concomitant production of chromium(III). Regeneration of CrVO by reaction of dioxygen with CrIII completes an aerobic catalytic cycle, with very large solvent effects; in acetonitrile, rapid initial turnovers observed initially are shut down by formation of CrIVO, while in toluene, THF, and methanol, relatively slow reactions are further inhibited by product formation.

Towards a universal polymer backbone: design and synthesis of polymeric scaffolds containing terminal hydrogen-bonding recognition motifs at each repeating unit.

Abstract: Polymers containing terminal hydrogen-bonding recognition motifs based on diaminotriazine and diaminopyridine groups in their side chains for the self-assembly of appropriate receptors have been prepared by ring-opening metathesis polymerization (ROMP) of norbornenes. A new synthetic method for the preparation of norbornene monomers based on pure alkyl spacers is introduced. These monomers show unprecedented high reactivity using ROMP. To suppress self-association of diaminotriazine-based polymers, polymerizations were run in presence of N-butylthymine. The butylthymine acts as a protecting group via self-assembly onto the hydrogen-bonding sites of the polymeric scaffold, thereby solubilizing the polymer. Diaminopyridine monomers do not require the presence of a protecting group due to their low propensity to dimerize. In addition, they exhibit a high affinity for hydrogen-bonded receptors on both monomeric and polymeric level. These polymers present our first building blocks towards the design and synthesis of a "universal polymer scaffold".

Highly efficient and selective epoxidation of alkenes by photochemical oxygenation sensitized by a ruthenium(II) porphyrin with water as both electron and oxygen donor.

Abstract: Visible light irradiation of a reaction mixture of carbonyl-coordinated tetra(2,4,6-trimethyl)phenylporphyrinatoruthenium(II) (RuIITMP(CO)) as a photosensitizer, hexachloroplatinate(IV) as an electron acceptor, and an alkene in alkaline aqueous acetonitrile induces selective epoxidation of the alkene with high quantum yield (Φ = 0.6, selectivity = 94.4% for cyclohexene and Φ = 0.4, selectivity = 99.7% for norbornene) under degassed conditions. The oxygen atom of the epoxide was confirmed to come from a water molecule by an experiment with H218O. cis-Stilbene was converted into its epoxide, cis-stilbeneoxide, without forming trans-stilbeneoxide. trans-Stilbene, however, did not exhibit any reactivity. Under neutral conditions, an efficient buildup of the cation radical of RuIITMP(CO) was observed at the early stage of the photoreaction, while an addition of hydroxide ion caused a rapid reaction with the cation radical to promote the reaction with reversion to the starting RuIITMP(CO). A possible involvemen...

Dihalogeno(diphosphane)metal(II) complexes (metal = Co, Ni, Pd) as pre-catalysts for the vinyl/addition polymerization of norbornene – elucidation of the activation process with B(C6F5)3/AlEt3 or Ag[closo-1-CB11H12] and evidence for the in situ formation of “naked” Pd2+ as a highly active species

Abstract: Dihalogenometal(II) complexes with bidentate phosphane ligands of the general type [M{Ph2P(CH2)nPPh2}X2] with n = 2 to 5, X = Cl or Br and M = Co, Ni or Pd have been utilized as catalysts for the vinyl/addition polymerization of norbornene. These complexes can be activated with the Lewis-acids methylalumoxane (MAO) or tris(pentafluorophenyl)borane, B(C6F5)3 in combination with triethylaluminium (AlEt3). The nickel(II) and palladium(II) complexes show very high polymerization activities up to 107 gpolymer molmetal−1 h−1. Yet, the complexes Pd(dppe)Cl2 (5, 1.9 × 107 gpolymer molPd−1 h−1) and Pd(dppp)Cl2 (6, 3.0 × 103 gpolymer molPd−1 h−1) demonstrated that small changes in the ligand structure could have great effects on the polymerization activity [dppe = 1,2-bis(diphenylphosphino)ethane, Ph2P(CH2)2PPh2; dppp = 1,3-bis(diphenylphosphino)propane, Ph2P(CH2)3PPh2]. The activation process of the pre-catalysts 5 and 6 in combination with B(C6F5)3/AlEt3 was followed by multinuclear (1H, 19F, and 31P) NMR investigations and by reaction with B(C6F5)3 and Ag[closo-1-CB11H12]. The reaction of B(C6F5)3 and AlEt3 leads to an aryl/alkyl group exchange resulting in the formation of AlEt3 − n(C6F5)n and B(C6F5)3 − nEtn with Al(C6F5)3 and BEt3 as main products for an about equimolar ratio. AlEt3 − n(C6F5)n will then react with the pre-catalysts and abstract the chloride atoms to form [M{Ph2P(CH2)nPPh2}]2+ as the active species for the polymerization. The higher polymerization activity of 5/B(C6F5)3/AlEt3 compared to 6/B(C6F5)3/AlEt3 can be explained by a ligand redistribution reaction of unstable [PdII(dppe)]2+ to give inactive and isolable [PdII(dppe)2]2+ and highly active, “naked” Pd2+ cations together with the lower coordinating ability of the anionic adduct [Cl–Al(C6F5)3]− in comparison to [Cl–B(C6F5)3]−. The Lewis-acid Al(C6F5)3 is much more activating than B(C6F5)3. The [Pd(dppe)2]2+ cation from the ligand redistribution was isolated in the (X-ray) structurally elucidated compounds [PdII(dppe)2][ClB(C6F5)3]2·4CH2Cl2 and [PdII(dppe)2][CB11H11Cl]2·3CH2Cl2. The stable [Pd(dppp)]2+ cation from 6 could be crystallized as [PdII(dppp)(CB11H12)][CB11H12] (CB11H12 = mono-anionic carborane [closo-1-CB11H12]−).

Homo- and Copolymerization of Norbornene and Styrene with Pd- and Ni-Based Novel Bridged Dinuclear Diimine Complexes and MAO

Abstract: Novel bridged dinuclear diimine nickel and palladium complexes catalyzed the vinyl addition polymerization of norbornene at a single active site with high activity. The latter exhibited higher activity thin the former Smaller substituents around the imido group in the ligand were more favorable for increasing the activity than bulkier ones. The polynorbornenes were all noncrystalline but had short-range older and their glass transition temperature, T g , ranged from 270 to 400°C. Furthermore, the random copolymerization of norbornene and styrene was catalyzed by the bridged dinucleqr diimine nickel complex with MAO (methylaluminoxane). Gel permeation chromatography (GPC), FTIR and 1 H NMR spectroscopies, wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) indicated that the copolymers are true copolymers. The reactivity ratios were r styrene = 0.281, r norbornen = 18.7. The packing density, thermostability and the glass transition temperatures of copolymers are increased relative to polystyrene. The solubility and processability of the copolymers are improved relative to polynorbornene.

Ethene/Norbornene Copolymerization with Palladium(II) α‐Diimine Catalysts: From Ligand Screening to Discrete Catalyst Species

Abstract: Sixteen palladium(II) alpha-diimine catalysts were investigated in a screening-like procedure for the copolymerization of ethene with norbornene. The resulting copolymers were characterized by (13)C NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and viscosimetry. The degree of incorporation of norbornene in the polymer chain is very high for most of the catalysts. To validate the results achieved in the screening, two catalysts, [[ArN=CHCH=NAr]Pd(Me)(CH(3)CN)]BAr(f) (4) (1 b'; Ar=2,6-Me(2)C(6)H(3), BAr(f) (4)=B[3,5-C(6)H(3)(CF(3))(2)](4)) and [[ArN=C(CH(3))C(CH(3))=NAr]Pd(Me)(CH(3)CN)]BAr(f) (4) (2 c'; Ar=2,6-iPr(2)C(6)H(3)), were synthesized as discrete catalytically active species, and their copolymerization behavior was investigated in detail. In agreement with the screening results, 1 b' incorporates norbornene much better in the polymer chain than ethene, a property that has no analogue in metallocene catalysts.

Cine-substitution in the Stille coupling: evidence for the carbenoid reactivity of sp3-gem-organodimetallic iodopalladio-trialkylstannylalkane intermediates.

Abstract: Two complementary routes to sp3-gem-organodimetallic iodopalladio-trialkylstannanylalkanes are presented. Such intermediates have been proposed as Pd-carbenoid precursors in the Busacca−Farina cine-substitution mechanism in the Stille coupling. The decomposition of iodomethyltrialkylstannanes by Pd(0) catalysts was monitored by 1H, 2D, and 119Sn NMR. The formation of ethylene, trace formaldehyde, and iodotrialkylstannanes was detected. When the reaction was carried out in the presence of norbornene, the corresponding cyclopropane was produced in good yield. These observations are consistent with the intermediacy of a Pd-carbenoid species. sp3-gem-Organodimetallic iodopalladio-trialkylstannanylalkane complexes were also prepared under stoichiometric conditions via transmetalation from tin to Pd(II). Me3SnCH2Sn(CH2CH2CH2)3 reacted with [(D-t-BPF)PdI]+I-, yielding the (D-t-BPF)Pd(II)ICH2SnMe3 complex that dimerized to form ethylene and cyclopropanated norbornene. The carbenoid reactivity of iodopalladio-tria...

Vinyl-type polymerization of norbornene by nickel(II) bisbenzimidazole catalysts

Abstract: Novel nickel(II) bisbenzimidazole complexes were prepared via a three-step synthetic procedure consisting of aniline/diacid condensation, ligand N-alkylation, and metal complexation. The complexes were characterized by X-ray crystallography and found to possess a pseudotetrahedral geometry. Upon activation with methylaluminoxane, these nickel bisbenzimidazoles did not polymerize simple olefins (e.g., ethylene, propylene, and 1-butene) but were found to carry out the rapid and efficient polymerization of norbornene. The polynorbornene products were characterized by gel permeation chromatography/light scattering, 13C NMR, and IR, and their Mark–Houwink and dn/dc parameters were determined. The molecular weights of the polynorbornenes were very high (weight-average molecular weight = 587,000–797,000 g/mol). 13C NMR suggested that the polymerization occurred via vinyl addition (i.e., a 2,3-linked polymer); no ring-opened product was observed. Thermogravimetric analysis indicated that the polynorbornenes were stable up to 400 °C under nitrogen. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2095–2106, 2003

Stereospecific Ring-Opening Metathesis Polymerization of Cycloolefins Using Novel Molybdenum and Tungsten Complexes Having Biphenolate Ligands. Development of Crystalline Hydrogenated Poly(endo-dicyclopentadiene) and Poly(norbornene)

Abstract: Novel molybdenum- and tungsten-based catalysts induced stereospecific ring-opening metathesis polymerization (ROMP) of cycloolefins to produce a new class of crystalline polymers. Various monomeric molybdenum(VI) and tungsten(VI) complexes of the general formula M(=O)(O−Ar)4 (M = Mo or W; (O−Ar)4 is two biphenolate or four phenolate ligands) were prepared. These catalysts exhibited moderate ROMP activity in the presence of cocatalyst such as n-BuLi and Et3Al. The molybdenum and tungsten complexes bearing substituted biphenolate ligands such as oxomolybdenum(VI) bis(racemic-5,5‘,6,6‘-tertamethyl-3,3‘-di-tert-butyl-1,1‘-biphenyl-2,2‘-diolate) promoted cis and isospecific ROMP of endo-dicyclopentadiene (cis > 90% and meso > 95%). The novel ternary and quarternary catalysts such as MoOCl4−biphenolate−n-BuLi (1:2:2) were developed as a new useful methodology to control the stereoselectivity of the ROMP. Hydrogenation of the cis-isotactic poly(endo-dicyclopentadiene)s and poly(norbornene)s provided novel crysta...

Catalytic Amplification of Patterning via Surface-Confined Ring-Opening Metathesis Polymerization on Mixed Primer Layers Formed by Contact Printing

Abstract: Thin films of polymers synthesized from strained olefins were formed on Si(100) via ring-opening metathesis polymerization (ROMP) initiated by a Ru−alkylidene catalyst bound to the surface by means of the alkylidene ligands. Specifically, a mixture of 7-octenyltrichlorosilane (3) and octyltrichlorosilane (4) was deposited onto Si/SiO2 surfaces via contact printing, and this assembly was subsequently treated with RuCl2(PCy3)2(CHPh) (1). The resulting surface-tethered Ru alkylidene complex reacts with norbornene derivatives to give thin polymer films. The growth of the polymer film, as monitored by ellipsometry, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM), is strongly influenced by the initial concentration of the catalyst at the surface and by the monomer reactivity. The catalyst concentration at the Si/SiO2 surface was controlled by adjusting the relative ratio of 3 and 4 in the “primer” used in the contact-printing step. These studies revealed that the success of the catalyt...

Probing the stereoselectivity of the ruthenium-catalyzed ring-opening metathesis polymerization of norbornene and norbornadiene diesters

Abstract: The ring-opening metathesis polymerization (ROMP) of two optically active 2,3-dicarboalkoxynorbornadienes derived from (S)-(−)-2-methyl-1-butanol and (R)-(−)-2-butanol were carried out in the presence of the [RuCl2(p-cymene)]2 catalyst precursor activated by trimethylsilyldiazomethane (TMSD). 1H and 13C NMR analyses showed that a high degree of stereoregularity was achieved, and homonuclear proton−proton COSY spectroscopy indicated that the major trans fractions of the polymers were most likely isotactic, while the minor cis fractions were syndiotactic. Ring-opened metathesis polymers were also made from 2,3-dicarbomethoxynorbornadiene and exo,exo-2,3-dicarbomethoxy-5-norbornene. They were hydrogenated into the corresponding polynorbornanes using diimide. The NMR spectra of the reduced materials confirmed that the unsaturated parent polymers had an all-trans highly isotactic microstructure. A tentative mechanism involving arene loss, carbene formation, and monomer chelation is proposed to account for the ...

Comparing intrinsic reactivities of the first- and second-generation ruthenium metathesis catalysts in the gas phase

Abstract: An experimental comparison of the gas-phase reactivity of the 14-electron reactive intermediates produced by phosphine dissociation from the first- and second-generation ruthenium metathesis catalysts, (L)Cl2RuCHR (L=PCy3 or NHC), supports Grubbs's contention that the second-generation catalysts show hundred-fold higher phenomenological activity despite a slower phosphine dissociation because of a much more-favorable partitioning of the 14-electron active species towards product-forming steps. The gas-phase study finds, in ring-opening metathesis of norbornene as well as acyclic metathesis of ethyl vinyl ether, that the first-generation systems display evidence for a higher barrier above that for phosphine dissociation; the second-generation systems, on the other hand, behave as if there is no significantly higher barrier.

Palladium(II) salts containing [PdCl4]2− and [Pd2Cl6]2− ions as pre-catalysts for the vinyl-polymerization of norbornene—evidence for the in situ formation of PdCl2 as the active species

Abstract: The polymerization behaviour of a new series of palladium(II) pre-catalysts in the vinyl-polymerization of norbornene has been investigated. Compounds containing [PdCl4]2− or [Pd2Cl6]2− anions and the organic cations [K(18-crown-6)]+, [H3O(18-crown-6)]+, [Ph3PCH2C(O)CH3]+ or [Him]+ (im = imidazole) can be activated with the Lewis acids methylalumoxane (MAO), tris(pentafluorophenyl)borane, B(C6F5)3 or a combination of B(C6F5)3/triethylaluminum (TEA). The catalytic systems show very high norbornene polymerization activities of up to 107 gpolymer molPd−1 h−1. In the case of an activation with B(C6F5)3 alone it is possible to obtain soluble palladium-catalyzed poly(norbornene)s which exhibit a fully saturated polymer backbone and a molar mass (Mn) between 8 × 103 and 3 × 105 g mol−1. The activation process of the pre-catalyst [Ph3PCH2C(O)CH3]2[Pd2Cl6] (2C) in combination with B(C6F5)3 can be followed by multinuclear (1H, 13C, 19F and 31P) NMR investigations and points to the in situ formation of PdCl2 which then represents the active species for the polymerization process. The X-ray structure of compound 2C is reported.

Metal-Catalyzed Addition Polymers for 157 nm Resist Applications. Synthesis and Polymerization of Partially Fluorinated, Ester-Functionalized Tricyclo[4.2.1.02,5]non-7-enes

Abstract: Fluorinated tricyclo[4.2.1.0^(2,5)]non-7-ene-3-carboxylic acid esters are shown to undergo metal-catalyzed addition polymerization. The resulting homopolymers are transparent at 157 nm and demonstrate the utility of these monomers in development of photoresists for 157 nm lithography. Fluorinated tricyclononene (TCN) structures with ester substituents exhibit up to 3 orders of magnitude more transparency at 157 nm than conventional ester-functionalized norbornene structures as determined by gas-phase vacuum-ultraviolet spectroscopy and variable angle spectroscopic ellipsometry. Unlike their fluorinated norbornene counterparts, the fluorinated, ester-functionalized TCN monomers successfully undergo transition-metal-catalyzed addition polymerization to produce polymers with high glass transition temperatures and the etch resistance required for photolithographic resist materials applications. The potential use of fluorinated TCN structures for 157 nm photoresists is demonstrated through the synthesis and characterization of TCN monomers and polymers.

Crosslinking and decomposition reactions of epoxide functionalized polynorbornene. Part I. FTIR and thermogravimetric analysis

Abstract: The miniaturization of microelectronic de- vices has created a demand for new low-dielectric-constant materials to be used as insulating layers between metal interconnects. In this study, a functionalized polynor- bornene consisting of a copolymer of decyl norbornene and epoxide norbornene has been investigated as a low-temper- ature curing dielectric. Polynorbornenes possess properties that are attractive for microelectronics packaging; however, films of these polymers must be crosslinked in order to obtain the solvent resistance and low solvent swelling nec- essary for multilayer applications. Crosslinking of these ma- terials was achieved by acid-catalyzed cationic crosslinking of epoxide side groups. The reactions that occurred during higher temperature curing of epoxy functionalized nor- bornene films were studied using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis. Epox- ide crosslinking and epoxide decomposition reactions were identified and studied as a function of temperature and time. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 568 -577, 2003

Highly active vinyl-polymerization of norbornene by [2-methyl-8-(diphenylphosphino)quinoline]nickel(II) dichloride/methylaluminoxane

Abstract: Polymerization of norbornene has been promoted by a catalyst system composed of [2-methyl-8-(diphenylphosphino)quinoline]nickel dichloride and MAO. The catalytic system showed high activity (activity 8 g-PNB/mol-Ni h) for vinyl addition type polymerization. The resultant polynorbornenes possessed high molecular weight ( M w 6 g/mol) with wide molecular weight distribution ( M w / M n

Gas Transport in Polymers Prepared via Metathesis Copolymerization of exo-N-Phenyl-7-oxanorbornene-5,6-dicarboximide and Norbornene

Abstract: This work reports the synthesis of exo-N-phenyl-7-oxanorbornene-5,6-dicarboximide and its ring-opening metathesis copolymerization with norbornene to yield poly(exo-N-phenyl-7-oxanorbornene-5,6-dicarboximide-co-norbornene), with molar ratio 50/50. The glass transition temperature of the copolymer is 125 °C. Permeation and sorption processes of different gases (hydrogen, nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethylene, and ethane) were measured in membranes prepared by casting from solutions of the copolymer in chloroform. The Langmuir capacity of the gases is relatively small due to the nearness of the glass transition temperature of the polymer to the working temperature. The solution of the most condensable gases in the continuous phase of the membrane is apparently described by the Flory−Huggins theory of polymer−diluent mixtures. In general, the membranes exhibit a reasonably high separation coefficient of hydrogen with respect to ethane, ethylene, nitrogen, and methane. The value...

Vinyl-polymerization of norbornene catalyzed by bis-[N-(substituted methyl)-salicylideneiminato]nickel/MAO system

Abstract: The bis-[ N -(substituted methyl)-salicylideneiminato]nickel/MAO systems were utilized to promote the vinylic homo-polymerization of norbornene. The results displayed that steric hindrance has significant effects on their catalytic activities for polymerization of norbornene. The complex a , bis-[ N -(diphenylmethyl)-salicylideneiminato]nickel, is systematically investigated with the catalytic activity up to 4.23×10 8 g PNB/(mol Ni h) and the average molecular weight up to 3.26×10 6 g/mol. All the polymer samples obtained here are soluble at room temperature in chlorobenzene. No indication of stereoregularity was observed; this was verified by the amorphous morphology of the products. The catalytic activities, yields, molecular weights and molecular weight distributions could be controlled over a wide range via variations of the reaction parameters.

Easily accessible and robust olefin-metathesis catalysts based on ruthenium vinylidene complexes

Abstract: Nine mixed ligand ruthenium(II) vinylidene complexes with the general formula: [RuCl 2 {CCHR′}(PCy 3 )(L)] and [RuCl{CCHR′}(PCy 3 )(sal-R)] (L= N -heterocyclic carbene, sal-R=salicylaldiminate anion, R′=Ph, SiMe 3 , t But ) has been synthesized and characterized These complexes are easily accessible from [RuCl 2 ( p -cymene)] 2 , terminal alkynes, imidazolium salts or salicylaldimine salts and they have been found to serve as good catalyst precursors for ring-opening metathesis polymerization (ROMP) of norbornene, substituted norbornenes, polycyclic alkenes and cyclooctene and ring-closing metathesis (RCM) of α,ω-dienes Furthermore, these precursors possess extremely high stability toward air, heat and moisture in comparison with other metathesis-active alkylidene ruthenium systems No significant catalyst decomposition was found for several days at elevated temperatures

Dinuclear Nickel(II) and Palladium(II) Complexes in Combination with Different Co-Catalysts as Highly Active Catalysts for the Vinyl/Addition Polymerization of Norbornene

Abstract: Dinuclear nickel(II) and palladium(II) complexes with Schiff-base ligands (derived form salicylaldehyde condensed with 2-amino-1-alcohols or from 2-hydroxy-5-methylisophthaldialdehyde and pyridine-2-carboxaldehyde condensed with semicarbazide, thiosemicarbazide, carbonodihydrazide, or thiocarbonodihydrazide) can be activated with the co-catalysts methylalumoxane (MAO) or tris(pentafluorophenyl)borane/triethylaluminium, B(C 6 F 5 ) 3 /AlEt 3 for the vinyl/addition polymerization of norbornene to reach activities of up to 2.4 .10 7 g p o l y m e r /mol(metal).h (molar ratios metal:Al M A O = 1:100, metal:borane:AlEt 3 = 1:9:10). Polymer characterization by GPC gave molar mass distributions of M w /M n 2, thereby indicating a coordination polymerization with a single-site character of the active species.

Vinyl polymerization of norbornene with dinuclear diimine nickel dichloride/MAO

Abstract: Vinyl-addition polymerization of norbornene was accomplished by two novel dinuclear diimine nickel dichloride complexes in combination with methylaluminoxane (MAO). The activities were moderate. The catalyst structure, Al/Ni molar ratio, solvents, and polymerization temperature all affected the catalytic activities. The obtained polynorbornenes were characterized by 1H-NMR, 13C-NMR, FTIR, DSC, WAXD, and intrinsic viscosity measurements. The vinyl-addition polymers were amorphous but with a short-range order and high packing density. The polynorbornenes showed glass transition temperatures (Tg) above 240°C and decomposed above 400°C. The catalyst structure and polymerization conditions have effects on the molecular weight and the microstructure of the polymers. The nickel complex with bulkier substituents in the ligand produced polynorbornene with a higher packing density and higher regularity and, therefore, with higher Tg. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3273–3278, 2003