Ethene−Norbornene Copolymerization Using Homogenous Metallocene and Half-Sandwich Catalysts:  Kinetics and Relationships between Catalyst Structure and Polymer Structure. 2. Comparative Study of Different Metallocene- and Half-Sandwich/Methylaluminoxane Catalysts and Analysis of the Copolymers by ¹³C Nuclear Magnetic Resonance Spectroscopy

Abstract

The kinetics of ethene-norbornene copolymerizations using the metallocenes iPr[(3-R-Cp)Ind]ZrCl2 (with R = methyl or tert-butyl), MeCH[Cp]2ZrCl2, iPr[(3-R-Cp)Flu]ZrCl2 (with R = H, methyl, isopropyl, or tert-butyl), and Me2Si[(3-tert-butyl-Cp)Flu]ZrCl2 and half-sandwich catalysts Me2Si[Me4CpNtBu]TiCl2, Me2Si[Me4CpNtBu]ZrCl2, Me2Si[FluNtBu]ZrCl2, R-(+)-Me2Si[Me4CpNCH(CH3)-1-naphthyl]TiCl2, and C2H4[Me4CpNMe2]Cr(eta1,eta1-C4H8) together with methylaluminoxane as cocatalyst, have been investigated at 70 degreesC in a concentrated solution of norbornene in toluene and under an ethene pressure ranging from 4 to 60 bar (58-870 psi). The ethene reaction rates were measured during the copolymerization process at various ethene concentrations and the ethene reaction orders were determined. In some cases fractional ethene reaction orders higher than 1 were found, indicating a complex mechanism. The microstructure of the copolymers were analyzed by 13C NMR spectroscopy. The highest norbornene contents were achieved using metallocenes with sterically less demanding ligands such as MeCH[Cp]2ZrCl2. Unexpectedly, low norbornene contents (<50 mol %) were achieved with the half-sandwich catalysts. Depending on the catalyst structure, the microstructure of the copolymers consists of mainly isolated norbornene units, alternating monomer sequences or short norbornene microblocks with a maximum length of two or three. Additionally, the tacticity of the norbornene microblocks could be controlled by the catalyst structure. A mechanistic model, based on chain migratory insertion, is presented to explain the different copolymer structures through nonbonding steric interactions between monomer, growing polymer chain, and ligand system. On the basis of this model, penultimate effects (Markov statistic second order) caused by the last two inserted monomer units can be assumed.

Chemical structure and physical properties of cyclic olefin copolymers (IUPAC Technical Report)

“…3. Between 28 and 33 ppm, the ethylene signals overlap with C5 and C6 resonances of 8,9,10-trinorbornane-2,3-diyl (norbornanediyl) [8,[12][13][14]. The norbornene content of the D series was determined by using the following relationship: [15] (2)…”

“…Most of these reports correlated the composition, microstructure, and thermal properties of ethene-norbornene copolymer [4][5][6][7][8]. A few studies have been made on the influence of chemical structure on the thermal properties of cyclic olefin copolymers.…”

Synthesis of High Performance Cyclic Olefin Polymers (COPs) with Ester Group via Ring-Opening Metathesis Polymerization

“…Based on performance characteristics, the applications of COCs and COPs have now been extended to production of optical parts for digital cameras and laser beam printers, medical products, and electrical insulation [1,4]. As shown in Scheme 1, COCs are obtained through copolymerization of cycloolefin with ethylene or α-olefin [5][6][7][8][9][10][11][12][13][14], and commercialized under the trade names APEL ® by Mitsui and TOPAS ® by TOPAS advanced polymers (TAP: formerly Ticona and Hoechst) [15,16]. COPs are prepared via ring-opening metathesis polymerization (ROMP) of cycloolefin followed by hydrogenation [17][18][19][20][21][22][23][24], and commercialized under the trade names Zeonex ® and Zeonor ® by Zeon [25] and Arton ® by Japan Synthetic Rubber (JSR) [20,21].…”

Microstructure of Copolymers of Norbornene Based on Assignments of 13C NMR Spectra: Evolution of a Methodology

“…The thorough microstructure investigation of E-co-N copolymers has taken several years [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. A number of groups dedicated great efforts to assign the 13 C NMR spectra of E-co-N copolymers.…”

“…Unfortunately, this approach when used alone is rather limited in assigning E-co-N copolymer spectra [23,24].…”