The Effect of SiMe₃ and SiEt₃Para Substituents for High Activity and Introduction of a Hydroxy Group in Ethylene Copolymerization Catalyzed by Phenoxide‐Modified Half‐Titanocenes

Abstract

Remarkable effects of SiMe 3 and SiEt 3 parasubstituents in the phenoxide-modified half-titanocenes, Cp*TiCl 2 (O-2,6-i Pr 2-4-R-C 6 H 2) [R= SiMe 3 (6), SiEt 3 (7)], toward the catalytic activities in ethylene copolymerizations with 2-methyl-1-pentene, 1-decene, 1-dodecene and with 9decen-1-ol (DC-OH) have been demonstrated. The activities by 6, 7 at 50 8C showed higher than those conducted at 25 8C in all cases in the presence of MAO cocatalyst. Efficient synthesis of high-molecular-weight (HMW) ethylene copolymers incorporating DC-OH (or 5-hexen-1-ol, HX-OH) has been attained in the copolymerization by 7, which showed better DC-OH (HX-OH) incorporation at 50 8C to afford the HMW copolymers, poly(ethylene-co-DC-OH)s, with high activities (activity 1.21-3.81 10 5 kg-polymer mol À1-Ti h, M n = 6.55-10.0 10 4 , DC-OH 2.3-3.6 mol %). Scheme 1. Synthesis of Cp*TiCl 2 (O-2,6-i Pr 2-4-R-C 6 H 2). R = Ph (3), CHPh 2 (4), CPh 3 (5), SiMe 3 (6), SiEt 3 (7)].

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

“…In particular, polymer molecular weight is the most serious obstacle from an application-orientated perspective, despite significant advancements over the past decades. [10,13,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Molecular weights is one of the most key parameters in olefin polymerization (also in any polymerization reaction), which determines the macroscopic chemical and physical properties of polymer materials. For instance, when it reaches an ultrahigh level (M n > 10 6 g mol -1 ), ultrahigh molecular weight polyethylene (UHMWPE), known as a kind of notably important thermoplastic materials, exhibits outstanding chemical and biological stability, high impact toughness, abrasion resistance and lubricity.…”