Effect of Cocatalyst in Ethylene/Styrene Copolymerization by Aryloxo‐Modified Half‐Titanocene–Cocatalyst Systems for Exclusive Synthesis of Copolymers at High Styrene Concentrations

Abstract

Factors affecting the product distributions in ethylene/styrene copolymerizations catalyzed by Cp à TiCl 2 (O-2,6-i Pr 2 C 6 H 3 ) are explored in the presence of various cocatalysts at high styrene/ ethylene feed ratios (at 40 and 55 8C). Ethylene/styrene copolymers were the sole product when the reactions were conducted in the presence of [PhN(H)Me 2 ][B(C 6 F 5 ) 4 ] and Al i Bu 3 /Al(octyl) 3 even at 55 and 70 8C, whereas syndiotactic polystyrene was by-produced when the polymerizations were performed at >40 8C in the presence of MAO; the ratios of the copolymer/SPS were affected by the reaction temperature as well as Al cocatalyst employed.

Half-Titanocenes Containing Anionic Ancillary Donor Ligands: Effective Catalyst Precursors for Ethylene/Styrene Copolymerization

“…However, resonances ascribed to carbons in SPS (marked as * ca. 40.8 and 44.1 ppm) also increased upon increasing the polymerization temperature (runs 2,3 in Figures 2b,c) [55].…”

“…For example, the resultant polymers were poly(ethylene-co-styrene)s when the copolymerization was conducted at 25 °C or 40 °C under ethylene 6 atm. (Table 5, runs 1,4), whereas SPS was by-produced when the reactions were conducted at 40 °C or 55 °C under ethylene 4 atm (runs 2-3,5) [55]. As shown in Figure 2a, resonances ascribed to two (head-to-tail) styrene repeating units (T  , S  ) in addition to resonances due to so-called pseudo random [S  , SS by tail-to-tail and/or SES (S = styrene, E = ethylene)] were observed in the NMR spectrum.…”

“…Although ethylene/styrene copolymerizations using the aryloxo-modified half-titanocenes, [52,53,58,90], it was revealed that syndiotactic polystyrene (SPS) was a by-produced when the polymerization was performed especially at a rather high temperature under high styrene concentrations [54,55]: the ratio of the copolymer/SPS was affected by the polymerization temperature and the [styrene]/[ethylene] feed molar ratio in the reaction mixture [54]. For example, the resultant polymers were poly(ethylene-co-styrene)s when the copolymerization was conducted at 25 °C or 40 °C under ethylene 6 atm.…”

“…Development of the catalyst systems for the exclusive synthesis should be thus considered as potentially important in terms of not only polymer synthesis, but also better understanding of polymerization mechanism, although the copolymers with high styrene contents can be easily prepared when the polymerizations were conducted at 25 ºC under high styrene concentrations [52,53]. (Table 6) [55]. The exclusive synthesis has been achieved even at 70 °C (run 13), and the styrene content exceeded 50 mol% under high styrene concentration conditions (run 12).…”

Synthesis of Ultrahigh Molecular Weight Polymers Containing Reactive Functionality with Low PDIs by Polymerizations of Long-Chain α-Olefins in the Presence of Their Nonconjugated Dienes by Cp*TiMe2(O-2,6-iPr2C6H3)–Borate Catalyst

“…On the basis of our previous reports for polymerizations of 1-decene (DC), 1-dodecene (DD), and 1-tetradecene (TD) [22], and of 1,7-octadiene [38] ; the ratios were used on the basis of the homo polymerization results [22]. As reported previously [22,29,[47][48][49], use of Al(n-C 8 H 17 ) 3 , weak reagent for alkylation, and/or chain transfer was effective to proceed without catalyst deactivation, probably not only due to a role as a scavenger, but also due to the fact that the Al alkyl would contribute to the stabilization of the catalytically active species by preventing the decomposition from further reaction with borate [50][51][52]. The results in the DC/DCD copolymerization are summarized in Table 1.…”