Notable norbornene (NBE) incorporation in ethylene–NBE copolymerization catalysed by nonbridged half-titanocenes: better correlation between NBE incorporation and coordination energy

Abstract

CpTiCl2(N=CtBu2) exhibits both remarkable catalytic activity and efficient norbornene (NBE) incorporation for ethylene-NBE copolymerization: the NBE incorporation by Cp'TiCl2(X) (X = N=CtBu2, O-2,6-iPr2C6H3; Cp' = Cp, C5Me5, indenyl) was related to the calculated coordination energy after ethylene insertion.

Design of Efficient Molecular Catalysts for Synthesis of Cyclic Olefin Copolymers (COC) by Copolymerization of Ethylene and α-Olefins with Norbornene or Tetracyclododecene

“…We demonstrated that the Cp-ketimide analogue, CpTiCl 2 (N=C t Bu 2 ) (7), exhibited remarkable catalytic activities, and a decrease in the activity was not observed, even after 30 min [24]. The activity increased upon increasing the initial NBE concentration, whereas, as described above, a decrease in activity was observed in other catalysts upon increasing NBE concentration.…”

“…This may also be explained by the fact that 7 showed remarkable catalytic activity for NBE homopolymerization. The resultant polymers possessed uniform compositions, confirmed by differential scanning calorimetry (DSC) thermograms as well as gel permeation chromatography (GPC) traces, and a linear relationship between glass transition temperatures and NBE content in the resultant poly(ethylene-co-NBE)s was observed [22][23][24][25].…”

“…It is noteworthy that neither activity nor NBE incorporation were strongly affected by the Al cocatalyst employed (methylaluminoxane (MAO), modified MAOs (MMAOs)), a fact that is in distinct contrast to that reported for the copolymerization by [Me 2 Si(fluorenyl)(N t Bu)]TiMe 2 (4) in which both the catalytic activity and NBE incorporation are highly dependent upon the Al cocatalyst employed [21]. Both the activity (of 7) and the NBE content in the copolymer increased at a higher temperature (40-80 • C), and the resultant copolymers possessed high molecular weights with unimodal molecular weight distributions (M n = 3.38 × 10 5 to 6.20 × 10 5 , M w /M n = 2.20-2.37) [24]. The efficient synthesis of high molecular weight copolymers with high NBE content (58.8-73.5 mol %) is possible upon increasing the NBE concentration at low ethylene pressure (2 atm).…”

“…Many have reported on ethylene copolymerization with norbornene (NBE) using ordinary metallocenes [10][11][12][13][14][15][16][17], half-titanocenes [18][19][20][21][22][23][24][25][26], and others [27][28][29][30], however, successful examples of the efficient synthesis of random, high molecular weight copolymers with high Tg values (high NBE content) have been limited. Ethylene copolymers with tetracyclododecene (TCD, dimethanooctahydronaphthalene) are also known as promising materials [9], and are produced by using classical Ziegler-type vanadium catalyst systems (VOCl3, VO(OEt)Cl2-EtAlCl2•Et2AlCl, etc.)…”

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].…”