Vinyl Addition Polymerization Of Norbornene Research Articles

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).

Catalytic performance of tridentate versus bidentate Co(ii) complexes supported by Schiff base ligands in vinyl addition polymerization of norbornene.

A series of Co(ii) complexes supported by Schiff base ligands, LA-LC, where LA, LB, and LC are (E)-3-methoxy-N-(quinolin-2-ylmethylene)propan-1-amine, (E)-N 1,N 1-dimethyl-N 2-(pyridin-2-ylmethylene)ethane-1,2-diamine, and (E)-N 1,N 1-dimethyl-N 2-(thiophen-2-ylmethylene)ethane-1,2-diamine, respectively, were designed and synthesized. Structural studies revealed a distorted trigonal bipyramidal geometry for [LBCoCl2] and a distorted tetrahedral geometry for [LCCoCl2]. After activation with modified methyl aluminoxane (MMAO), all the Co(ii) complexes catalyzed the polymerization of norbornene (NB) to yield vinyl-type polynorbornenes (PNBs) with activities of up to 4.69 × 104 gPNB mol Co-1 h-1 at 25 °C. High-molecular-weight (M n of up to 1.71 × 105 g mol-1) soluble PNBs with moderate molecular-weight distributions (MWD) were obtained. The activity of the Co(ii)/MMAO catalytic system is influenced by the steric hindrance and electronic properties of the ligands.

Pd(acac)(PR3)(PhCN)][BF4] and [Pd(acac)(S)2][BF4] (R = phenyl, 2-methoxyphenyl; S = benzonitrile, pyridine): Synthesis, characterization, reactivity and catalytic behavior. Crystal structure of Pd(κ2-O,O′-acac)(κ1-C-acac)(P(2-MeOC6H4)3)

The Pd(II)complexes [Pd(acac)(PR3)(PhCN)][BF4] and [Pd(acac)(S)2][BF4] (acac = acetylacetonate; R = phenyl, 2-methoxyphenyl; S = benzonitrile, pyridine, CD3CN) were synthesized by the reaction of Pd(acac)2 or Pd(acac)2·PR3 with 2 equiv. of BF3·OEt2 in the presence of appropriate ligands (S). The structural features of the complexes were analyzed by NMR and FTIR spectroscopies. Computed FTIR spectra was in agreement with the corresponding experimental data, the correlation between ν(CN) of the κ1-nitrile ligands and DFT-calculated geometrical features of the complexes was proposed. Complex Pd (κ2-O,O′-acac)(κ1-C-acac)(TOMPP) (TOMPP = tris(ortho-methoxyphenyl)phosphine) was characterized by X-ray diffractometry. XRD, 1H and 31P NMR analyses were consistent with formation of three unequally populated rotamers of Pd(κ2-O,O′-acac)(κ1-C-acac)(TOMPP) in CDCl3 which differ in the orientation of the endo-(2-methoxy)phenyl ring in exo2 conformation of coordinated TOMPP. Reaction of [Pd(acac)(PR3)(PhCN)]BF4 with L (L = pyridine, morpholine, TOMPP) in the majority of cases gave mixtures of [Pd(acac)(PR3)(L)]BF4, [Pd(acac)(L)2]BF4, and [Pd(acac)(PR3)2]BF4 as result of sequence of ligand substitution reactions. The cationic palladium catalyst precursors were found to be active catalysts for phenylacetylene polymerization and oligomerization. Only cationic pre-catalysts with bulky TOMPP ligand gave high-molecular weight polyphenylacetylene. Catalysts with less bulky substituents mostly formed phenylacetylene oligomers. When activated with BF3⋅OEt2, these palladium complexes can also be used as catalysts for the vinyl addition polymerization of norbornene with activities 104–107 gpolymer molPd h−1.

(Invited) High Conductivity, Stable Anion Conducting Membranes Based on Poly(norbornene)

Alkaline exchange membranes (AEM) fuel cells and electrolyzers are potentially cost-saving alternatives to traditional proton exchange membrane (PEM) devices. Recently, anion conducting polymer membranes have achieved ionic conductivity and chemical stability comparable to Nafion, the current state of the art in PEM technology. Phase segregation is an effective way to achieving high hydroxide mobility. An all-carbon backbone with light cross-linking and a long, alkyl tether for the cation head-group are effective means of achieving chemical stability and limiting unwanted water hydration. In this study, a series of tetrablock copolymers containing an all-hydrocarbon backbone and tethered quaternary ammonium groups were synthesized based on vinyl addition polymerization of norbornene. Several variations of block copolymer AEMs with different ion exchange capacities (IEC) were made by adjusting the ratio of hydrophilic to hydrophobic blocks. Correlations were found between the ionic conductivity and mechanical properties to the polymer structure, channel size, and degree of phase separation. Furthermore, it was found that light crosslinking of the membranes allows for high IEC materials to be used while maintaining acceptable water uptake. The crosslinked AEMs have demonstrated record-high hydroxide conductivities (198 mS/cm) for a chemically stable polymer. The chemical degradation at 80oC in 1 M KOH was <1% degradation in 1,200 hours. The AEMs were also used to construct MEAs for alkaline fuel cells.

Highly Conductive Anion-Exchange Membranes Based on Cross-Linked Poly(norbornene): Vinyl Addition Polymerization

Cross-linked (XL) anion-exchange membranes (AEMs) synthesized by vinyl addition polymerization of norbornene were prepared for use in anion-exchange membrane electrochemical devices, including fuel...

Anionic multiblock copolymer membrane based on vinyl addition polymerization of norbornenes: Applications in anion-exchange membrane fuel cells

Stable, non-hydrolysable, hydroxide-conducting polymers are of interest for electrochemical devices such as fuel cells, electrolyzers and flow-batteries. In this study, a series of tetrablock copolymers containing an all-hydrocarbon backbone were synthesized. The synthesis is based on vinyl addition polymerization of norbornene using (η3-allyl)Pd(iPr3P)Cl as the catalyst and lithium tetrakis(pentafluorophenyl)-borate·(2.5Et2O) (Li[FABA]) as the activator. The tetrablock polymers were cast into membranes with an ion-exchange capacity (IEC) between 1.55 and 2.60 milliequivalents per gram (meq/g). The number of bound and unbound water molecules per ion pair was measured and correlated with conductivity. The membrane with the highest IEC (2.60 meq/g) had 10.6 unbound (i.e. free) and 17.9 bound water molecules per ion pair within the polymer. The presence of excess unbound water has led to flooding of the ion conductive channels and low hydroxide ion conductivity. The optimal anion conductivity was found with about 6.7 unbound and 11.9 bound water molecules per ion pair. Excellent hydroxide conductivity (>120 mS/cm at 80 °C) was obtained at an ion-exchange capacity of 1.88 meq/g. The results show that hydroxide mobility is aided by phase segregation within the copolymer. The ion conducting polymer was stable in 1 M NaOH solution at 80 °C, showing essentially no loss in ion conductivity in 1200 h. Thermogravimetric analysis showed that the membrane backbone was stable up to 400 °C, consistent with previous polynorbornene-based materials. The peak power density of a H2/O2, hydroxide conducting fuel cell containing one of these membranes was 542.57 mW/cm2 at 0.43 V and current density of 1.26 A/cm2 at 60 °C.

Highly active nickel(II) and palladium(II) complexes bearing N,N,P tridentate ligand for vinyl addition polymerization of norbornene

A series of nickel (II) complexes (1a-4a) and palladium (II) complexes (1b-4b) bearing N,N,P tridentate ligands derived from amino-alkyl phosphines and 2-pyridinecarboxaldehyde and 2-quinolinecarboxaldehyde were synthesized and characterized. X-ray diffraction analysis revealed that complexes 1a, 4a, and 2b adopted square-pyramidal geometry, trigonal bipyramid, and distorted square-planar geometry, respectively. Activated by methylaluminoxane (MAO), all the complexes were highly active for norbornene polymerization in a vinyl addition fashion, affording high molecular weight polymers with narrow molecular weight distributions. The activities of palladium complexes are particularly notable; the highest activity reached 2.45×108g PNB (mol of Ni)−1h−1. The activities of the complexes were affected by the ligand structure as well as the reaction parameters such as polymerization temperature, time, and cocatalyst loading.

Synthesis and Reactivity of a Zwitterionic Palladium Allyl Complex Supported by a Perchlorinated Carboranyl Phosphine

A zwitterionic palladium complex of a phosphine bearing a perchlorinated carba-closo-dodecaborate anion as a ligand substituent is reported. A single-crystal X-ray diffraction study reveals that, in the solid state, one of the chlorides of the carborane cage occupies a coordination site of the square-planar complex. However, in solution, the P-carborane bond of the ligand is rapidly rotating at temperatures as low as -90 °C, which demonstrates the carborane substituent's weak coordinative ability even though this anion is covalently linked to the phosphine ligand. The complex is thermally stable and catalyzes the vinyl addition polymerization of norbornene.

Cationic palladium(II)–acetylacetonate complexes bearing α-diimine ligands as catalysts in norbornene polymerization

A variety of palladium(II)–acetylacetonate complexes bearing α-diimine ligands were synthesized by the reaction of [Pd(acac)(MeCN)2]BF4 with N⁀N ligands. When activated with BF3·OEt2, these complexes provide access to a new class of alkylating agent free Pd–diimine catalyst systems. Catalyst screening for the vinyl addition polymerization of norbornene showed their high activities of 102–104kgpolmolcat−1h−1.

Nickel complexes bearing N,N,N-tridentate quinolinyl anilido–imine ligands: Synthesis, characterization and catalysis on norbornene addition polymerization

The N,N,N-tridentate quinolinyl anilido–imine ligands 2-(ArNC(H))C6H4–HNC9H6N (LaH, Ar = 2,6-Me2C6H3; LbH, Ar = 2,6-iPr2C6H3) and 2-(C9H6N)NC(H)C6H4–HNAr (LcH, Ar = 2,6-Me2C6H3; LdH, Ar = 2,6-iPr2C6H3) were synthesized and characterized. Reactions of these ligands with nBuLi and subsequent additions of NiCl2(DME) afford the N,N,N-tridentate nickel complexes [2-(ArNC(H))C6H4–NC9H6N]NiCl (Ar = 2,6-Me2C6H3 (1a), 2,6-iPr2C6H3 (1b)) and [2-(C9H6N)NC(H)C6H4–NAr]NiCl (Ar = 2,6-Me2C6H3 (2a), 2,6-iPr2C6H3 (2b)). All the complexes were fully characterized by NMR and elemental analyses. X-ray diffraction analyses of 1b and 2b revealed an almost square-planar geometry around the metal center. When activated with MAO, these nickel complexes can be used as catalysts for the vinyl addition polymerization of norbornene affording high molecular weight polymer.

Vinyl addition polymerization of norbornene catalyzed by β-iminoamine Ni(II) complexes/methylaluminoxane systems

Two nickel(II) complexes ( A and B) bearing β-iminoamine ligands, [2-(ArN CH)-C 6H 4-NMe 2] ( La, Ar = 2,6-i-Pr 2C 6H 3; Lb, Ar = 2,6-Me 2C 6H 3), were synthesized and characterized by elemental analyses and 1H NMR. X-ray crystal structure of complex B reveals that the six-membered chelate ring adopts a envelope conformation, with nickel(II) atom deviating from the plane of backbone aromatic ring by 1.164 Å. In the presence of methylaluminoxane (MAO), both complexes showed moderate activities of 10 5 g mol Ni −1 h −1 for norbornene polymerization. β-iminoamine Ni(II)/MAO catalysts gave unimodal polymers ( M w, 3.16–8.02 × 10 5 g/mol) with a relatively narrow MWD ( M w/ M n, 1.59–2.14), indicative of single-site catalyst behavior. The obtained polymers are vinyl-type polynorbornenes (PNBs), which are soluble in common solvents such as toluene, cyclohexane and dichlorobenzene.

Novel heteroligated titanium complexes with fluorinated salicylaldiminato and β-enaminoketonato ligands: synthesis, characterization and catalytic behavior in vinyl addition polymerization of norbornene

A series of heteroligated (salicylaldiminato)(β-enaminoketonato)titanium complexes of the general formula [3-Bu(t)-2-OC(6)H(3)CH==N(C(6)F(5))][PhN==C(CF(3))CHC(R)O]TiCl(2) (3a: R==Ph, 3b: R==C(6)H(4)Ph(p), 3c: R==C(6)H(4)Ph(o), 3d: R = 1-naphthyl, 3e: R = C(6)H(4)F2(2,6), 3f: R = C(6)H(4)Cl2(2,5), 3g: R==C(6)F4(2,3,5,6)OMe(4)) were synthesized. The structure of complexes 3d, 3f-g were determined by single crystal X-ray diffraction analysis. The X-ray crystallographic analysis indicated these complexes adopted a distorted octahedral geometry around the titanium center. Upon activation with modified methylaluminoxane, complexes 3a-g exhibited moderate to good catalytic activity for norbornene (NB) vinyl addition polymerization, producing moderate molecular weight polynorbornenes under mild conditions. The introduction of electron-withdrawing groups can greatly enhance the catalytic activity. Significantly, the heteroligated titanium complexes displayed greatly improved activity for vinyl addition polymerization of NB compared to homoligated counterparts, which may stem from the suitable combinations of electronic and steric effects.

η 5-Cyclopentadienylpalladium(II) complexes: Synthesis, characterization and use for the vinyl addition polymerization of norbornene and the copolymerization with 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene

Dinuclear complexes of palladium(II), containing two bridging halogen (Cl or Br) ligands, [N n Bu 4] 2[(X 5C 6) 2Pd(μ-Cl) 2Pd(C 6X 5) 2] and [(X 5C 6)(L)Pd(μ-Y) 2Pd(C 6X 5)(L)] (X = F, Cl; Y = Cl, Br), readily react with cyclopentadienylthallium, C 5H 5Tl, to give the corresponding air stable half-sandwich, pseudo-trigonal η 5-cyclopentadienylpalladium complexes, [N n Bu 4][(η 5-C 5H 5)Pd(C 6X 5) 2] (X = F 1, Cl 2) and (η 5-C 5H 5)Pd(C 6X 5)(L) (X = F, L = CNBu t 3, PPh 3 4, PMe 2Ph 5, PEt 3 6, AsPh 3 7, SbPh 3 8; X = Cl, L = PMe 2Ph 9, PEt 3 10), respectively. With tetraphenylcyclopentadienylthallium, C 5Ph 4HTl or pentabenzylcyclopentadienylthallium, C 5Bn 5Tl (Bn = CH 2Ph) the air stable half-sandwich complexes (η 5-C 5Ph 4H)Pd(C 6F 5)(AsPh 3), 12 and (η 5-C 5Bn 5)Pd(C 6F 5)(AsPh 3), 13 are synthesized accordingly. The molecular structures were verified by NMR-spectroscopy, X-ray crystallography ( 7, 12, 13) and electron impact-mass spectrometry (EI-MS). The precatalysts 4 and 7 can be activated with methylalumoxane (MAO) for the homopolymerization of norbornene (NB) and 5-ethylidene-2-norbornene (ENB) and for the copolymerization of NB with 5-vinyl-2-norbornene (VNB) or ENB with activities of more than 10 6 g PNB/(mol Pd·h). The higher activity of 7/MAO over 4/MAO towards NB homopolymerization was reversed when the olefin-substituted VNB or ENB were added. Then, the more strongly bound PPh 3 ligand of 4 (versus AsPh 3 of 7) can compete with the olefin functionality of VNB or ENB and assume a directing role for the insertion of the ring double bond. As a consequence 4/MAO shows almost the same activity in NB and ENB homopolymerization.

Palladium(ii) complexes with pentafluorophenyl ligands: structures, C6F5 fluxionality by 2D-NMR studies and pre-catalysts for the vinyl addition polymerization of norbornene

The palladium(II) complex [Pd(C(6)F(5))Cl(bpzm*)] (5) [bpzm* = bis(3,5-dimethylpyrazol-1-yl)methane] was characterized by (1)H,(1)H-TOCSY, (1)H-NOE difference spectra, (1)H,(19)F-HOESY and (13)C,(1)H-HMBC 2D-NMR techniques. Chemical exchange of the methylene protons from (1)H,(1)H-NOESY cross peaks and exchange of the ortho- and meta-fluorine atoms, respectively, from (19)F,(19)F-EXSY cross peaks indicates that the Pd-bpzm* chelate ring boat-to-boat inversion occurs at a rate slower than the NMR time scale together with a concomitant change of the C(6)F(5) atom positions. The presence of three (19)F-NMR signals for 2F(o) : 1F(p) : 2F(m) of the C(6)F(5) ligand for complexes [Pd(C(6)F(5))Cl(tmeda)] (1) and [Pd(C(6)F(5))Cl(bipy)] (3) (tmeda = N,N,N',N'-tetramethylethylenediamine; bipy = 2,2'-bipyridine) is interpreted as being due to identical hemi-spaces above and below an apparent symmetry plane coinciding with the Pd-coordination plane instead of free ring rotation. The molecular structures of 1, 3 and 5 from single-crystal studies suggest that the hindered C(6)F(5) rotation is not limited to 5 but is also present in 1 and 3 due to ligand repulsion. Complexes [Pd(C(6)F(5))Cl(tmeda)] (1), [Pd(C(6)F(5))OH(tmeda)] (2), [Pd(C(6)F(5))Cl(bipy)] (3), [Pd(C(6)F(5))OH(bipy)] (4) and [Pd(C(6)F(5))Cl(bpzm*)] (5) have been applied as pre-catalysts for the vinyl homopolymerization of norbornene in combination with the cocatalyst methylaluminoxane (MAO). Activities of more than 10(6) g(polymer)/(mol(Pd) h) could be reached with these catalytic systems. Based on the spectrochemical series, pre-catalysts 1 and 2 with the pure sigma-donor and more weakly bound aliphatic amine ligands showed higher polymerization activities than compounds 3-5 with modest pi-accepting and stronger bound aromatic substituents. This is reasoned with a kinetic activation effect through a faster removal of the more weakly bound ligands upon reaction with MAO together with the chloro or hydroxo ligands to give the active, almost "naked" Pd(2+) cations. For the activation mechanism, (1)H-, (13)C- and (19)F-NMR studies of the MAO activated complex 5 showed about 13% chlorine-to-methyl exchange for a molar Pd : Al ratio of 1 : 10. For 5 : MAO at a Pd : Al ratio of 1 : 100 abstraction of C(6)F(5) takes place with a redox reaction giving Pd metal and C(6)F(5)-CH(3) in the absence of norbornene monomer.

γ-Agostic Species as Key Intermediates in the Vinyl Addition Polymerization of Norbornene with Cationic (allyl)Pd Catalysts: Synthesis and Mechanistic Insights

Several cationic (allyl)Pd(II) complexes were synthesized and shown to be highly active for (2,3)-vinyl addition polymerization of norbornene (NB) to yield polymers with low molecular weight distributions (MWDs) ranging from 1.2-1.4. Despite the low MWDs, slow initiation was followed by rapid propagation preventing molecular weight control of the poly(norbornene). Several intermediates in these polymerizations initiated with [(2-R-allyl)Pd(mesitylene)](+) complexes were fully characterized (NMR and X-ray diffraction). Consistent with previous observations the allyl and NB units couple in cis-exo fashion to yield a sigma,pi-complex capped by mesitylene. Mesitylene is readily displaced by NB to form an agostic intermediate in which NB acts as a bidentate ligand and binds to the cationic Pd center via the pi-system and a gamma-agostic interaction with the syn hydrogen at C7. The identity of this complex was established by NMR spectroscopy and single-crystal X-ray diffraction. It is significant since it suggests bidentate binding of NB in the propagating species, which cannot be observed by NMR spectroscopy. The NMR studies suggest that the second insertion, i.e., insertion of NB in the agostic intermediate, is the slow initiation step and the subsequent insertions are extremely fast. Therefore, slow chelate opening is the major limitation preventing a living polymerization. This hypothesis was explored using a series of cationic substituted pi-allyl complexes; significantly increased reactivity was observed when electron-withdrawing groups were introduced into the allyl moiety. However, despite these modifications initiation remained slow relative to chain propagation.

Vinyl addition polymerization of norbornene with cationic (allyl)Ni catalysts: Mechanistic insights and characterization of first insertion products

AbstractSeveral cationic (allyl)Ni(II) complexes were synthesized and shown to be highly active for (2,3)‐vinyl addition polymerization of norbornene to yield polymers with low molecular weight distributions (MWDs) ranging from 1.4–1.9. In all cases slow initiation was followed by rapid propagation which prevents molecular weight control of the poly(norbornene). One of the intermediates in the polymerization process has been identified and characterized by NMR spectroscopy as the first insertion product resulting from the insertion of norbornene into the NiC allyl bond in cis‐exo fashion. This insertion product was synthesized independently and NMR studies showed that the first insertion of norbornene into the NiC allyl bond is a reversible process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2560–2573, 2009

γ-Agostic interactions stabilize the propagating species in the vinyl addition polymerization of norbornene

Cationic [(tmeda)Pd(OEt(2))(Me)][B(Ar(F))(4)] was synthesized by protonation of (tmeda)PdMe(2) and allowed for the first time the nature of the propagating species in the vinyl addition polymerization of norbornene to be discerned. In this system gamma-agostic interactions stabilize the propagating species and permit stepwise monomer insertions to be observed by (1)H NMR spectroscopy. This and earlier studies provide a new proposal for the propagating species in ligand-less late transition metal-catalyzed norbornene polymerizations.

Synthesis and Characterization of Pyrrole-imine [N−NP] Nickel(II) and Palladium(II) Complexes and Their Applications to Norbornene Polymerization

Ni(II) and Pd(II) complexes based on N-((1H-pyrrol-2-yl)methylene)-2-(diphenylphosphino)benzenamine were synthesized and characterized. X-ray diffraction studies on complexes 1, 2, and 4 revealed that N, N, P, and halogen atoms coordinated to metal, with distorted square planar geometries in all cases. Upon treatment with modified methylaluminoxane (MMAO), the [N−NP]Ni(II)X complexes are robust and exhibit high activity for the vinyl addition polymerization of norbornene (up to 5.46 × 107 g PNB/mol(Ni)·h·atm).

Vinyl addition polymerization of norbornene using cyclopentadienylzirconium trichloride activated by isobutyl-modified methylaluminoxane

Norbornene polymerization using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3) and isobutyl-modified methylaluminoxane (MMAO), were carried out over a wide range of polymerization temperatures and monomer concentrations. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO40/60), the polymerization temperature and monomer concentration significantly affected the molecular weight (Mn) of the obtained polymer and the catalytic activity. With an increase in the polymerization temperature from 0 to 27 °C, the catalytic activity and Mn increased, but these values dramatically decreased with the increasing polymerization temperature from 27 to 70 °C, meaning that the most suitable temperature was 27 °C. The CpZrCl3/MMAO40/60 ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.76 mol L−1 at 27 °C showed the highest activity of 145 kg molZr−1 h−1 and molecular weight of 211,000 g mol−1. The polymerization using the CpZrCl3/MMAO40/60 catalyst system proceeds through the vinyl addition mechanism to produce atactic polynorbornene, which was soluble in chloroform, toluene, and 1,2-dichlorobenzene, but insoluble in methanol. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1185–1191, 2008

Homo‐ and copolymerization of norbornene derivatives with ethene by ansa‐fluorenylamidodimethyltitanium activated with methylaluminoxane

Abstract(t‐BuNSiMe2Flu)TiMe2 (1) activated with Me3Al‐free methylaluminoxane (dried MAO) which conducts vinyl addition polymerization of norbornene (N) with very high activity was applied for homopolymerization of N derivatives (i.e., 5‐vinyl‐2‐norbornene (5V2N), 5‐ethylidene‐2‐norbornene (5E2N), dicyclopentadiene (DCPD)) at 40 °C. The activities for the N derivatives were about two orders of magnitude lower than that for N and decreased in the following order: 5E2N ≫ 5V2N ≫ DCPD. Copolymerization of ethene (E) and 5E2N under an atmospheric pressure of E was then conducted by 1‐dried MAO. The copolymerization proceeded with better activity than the homopolymerization of 5E2N and gave poly(E‐co‐5E2N) with narrow molecular weight distribution. The content of the ethylidene group in poly(E‐co‐5E2N) was controlled by the feed ratio of 5E2N/E. The Tg value of the copolymer changed from 70 °C to 155 °C according to the 5E2N content from 27 mol % to 68 mol %. The addition of N as a third monomer to the E‐5E2N copolymerization improved the activity and raised the Tg values of the terpolymer above 200 °C. The content of 5E2N was controlled by the 5E2N/N ratio with keeping the high Tg values. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4581–4587, 2007