Synthesis of Ultrahigh Molecular Weight Polymers with Low PDIs by Polymerizations of 1-Decene, 1-Dodecene, and 1-Tetradecene by Cp*TiMe2(O-2,6- i Pr2C6H3)⁻Borate Catalyst

Abstract

Polymerizations of 1-decene (DC), 1-dodecene (DD), and 1-tetradecene (TD) by Cp*TiMe₂(O-2,6-ⁱPr₂C₆H₃) (1)-[Ph₃C][B(C₆F₅)₄] (borate) catalyst have been explored in the presence of Al cocatalyst. The polymerizations of DC and DD, in n-hexane containing a mixture of AlⁱBu₃ and Al(n-C₈H₁₇)₃, proceeded with high catalytic activities in a quasi-living manner, affording high molecular weight polymers (activity 4120-5860 kg-poly(DC)/mol-Ti·h, M_n for poly(DC) = 7.04-7.82 × 10⁵, after 20 min at -30 °C). The PDI (M_w/M_n) values in the resultant polymers decreased upon increasing the ratio of Al(n-C₈H₁₇)₃/AlⁱBu₃ with decreasing the activities at -30 °C. The PDI values also became low when these polymerizations were conducted at low temperatures (-40 or -50 °C); high molecular weight poly(DD) with low PDI (M_n = 5.26 × 10⁵, M_w/M_n = 1.16) was obtained at -50 °C. The TD polymerization using 1-borate-AlⁱBu₃ catalyst (conducted in n-hexane at -30 °C) afforded ultrahigh molecular weight poly(TD) (M_n = 1.02 × 10⁶, M_w/M_n = 1.38), and the PDI values also decreased with increasing the Al(n-C₈H₁₇)₃/AlⁱBu₃ ratio.

Keywords: borate; catalyst; half-titanocene; polymerization; titanium complex; α-olefin.