Efficient introduction of aromatic vinyl group by incorporation of divinylbiphenyl,p‐divinylbenzene in syndiospecific styrene polymerization using aryloxo‐modified half‐titanocene catalysts

An efficient introduction of aromatic vinyl group into syndiotactic polystyrene has been achieved by incorporation of 3,3′‐divinylbiphenyl, p‐divinylbenzene (DVB) in syndiospecific styrene polymerization using aryloxo‐modified half‐titanocenes, Cp′TiCl₂(O‐2,6‐ⁱPr₂C₆H₃) (Cp′ = ^tBuC₅H₄, 1,2,4‐Me₃C₅H₂), in the presence of MAO. The resultant polymers possessed high molecular weights with uniform molecular weight distributions, and the DVB contents could be varied by the initial feed molar ratios (6–23 mol %) without decrease in the M_n values. The syndiotactic stereo‐regularity and presence of the vinyl groups were confirmed by NMR spectra. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1902–1907     

Efficient synthesis of cyclic olefin copolymers with high glass transition temperatures by ethylene copolymerization with tetracyclododecene using (tert‐BuC5H4)TiCl2(N=CtBu2)—MAO catalyst

(^tBuC₅H₄)TiCl₂(N=C^tBu₂) ( 1 ) exhibited remarkable catalytic activities (12,000–43,700 kg‐polymer/mol‐Ti·h) and efficient comonomer incorporation in ethylene copolymerization with tetracyclododecene (TCD) in the presence of methylaluminoxane, and the catalytic activity by 1 increased even at 60 °C. The resultant polymers are high molecular weight amorphous poly(ethylene‐co‐TCD)s (M_n = 5.88–7.03 × 10⁵) with uniform compositions (with high T_g values, 108–203 °C); a linear relationship between T_g values and the TCD contents was observed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2662–2667     

Efficient terpolymerization of ethylene and styrene with α‐olefins by aryloxo‐modified half‐titanocene‐based catalysts and cocatalyst systems

Aryloxo‐modified half‐titanocenes, Cp′TiCl₂(O‐2,6‐ⁱPr₂C₆H₃) [Cp′ = Cp* ( 1 ), ^tBuC₅H₄ ( 2 )], catalyze terpolymerization of ethylene and styrene with α‐olefin (1‐hexene and 1‐decene) efficiently in the presence of cocatalyst, affording high‐molecular‐weight polymers with unimodal distributions (compositions). Efficient comonomer incorporations have been achieved by these catalysts. The content of each comonomer (α‐olefin, styrene, etc.) could be controlled by varying the comonomer concentration charged, and resonances ascribed to styrene and α‐olefin repeated insertion were negligible. The terpolymerization with p‐methylstyrene (p‐MS) in place of styrene also proceeded in the presence of [PhN(H)Me₂][B(C₆F₅)₄] and AlⁱBu₃ cocatalyst, and p‐MS was incorporated in an efficient matter, affording high‐molecular‐weight polymers with uniform molecular weight distributions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2565–2574     

Introduction of reactive functionality by the incorporation of divinylbiphenyl in ethylene copolymerization with styrene or 1‐hexene using aryloxo‐modified half‐titanocenes and MAO catalysts

An efficient introduction of vinyl group into poly (ethylene‐co‐styrene) or poly(ethylene‐co?1‐hexene) has been achieved by the incorporation of 3,3′‐divinylbiphenyl (DVBP) in terpolymerization of ethylene, styrene, or 1‐hexene with DVBP using aryloxo‐modified half‐titanocenes, Cp′TiCl₂(O?2,6‐ⁱPr₂C₆H₃) [Cp′ = Cp*, ^tBuC₅H₄, 1,2,4‐Me₃C₅H₂], in the presence of MAO cocatalyst, affording high‐molecular‐weight polymers with unimodal distributions. Efficient comonomer incorporations have been achieved by these catalysts, and the content of each comonomer could be varied by its initial concentration charged. The postpolymerization of styrene was initiated from the vinyl group remained in the side chain by treatment with n‐BuLi. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2581–2587     

Efficient ethylene/norbornene copolymerization by half‐titanocenes containing imidazolin‐2‐iminato ligands and MAO catalyst systems

Ethylene copolymerizations with norbornene (NBE) using half‐titanocenes containing imidazolin‐2‐iminato ligands, Cp′TiCl₂[1,3‐R₂(CHN)₂C?N] [Cp′ = Cp ( 1 ), ^tBuC₅H₄ ( 2 ); R = ^tBu ( a ), 2,6‐ⁱPr₂C₆H₃ ( b )], have been explored in the presence of methylaluminoxane (MAO) cocatalyst. Complex 1a exhibited remarkable catalytic activity with better NBE incorporation, affording high‐molecular‐weight copolymers with uniform molecular weight distributions, whereas the tert‐BuC₅H₄ analog ( 2a ) showed low activity, and the resultant polymer prepared by the Cp‐2,6‐diisopropylphenyl analog ( 1b ) possessed broad molecular weight distribution. The microstructure analysis of the poly(ethylene‐co‐NBE)s prepared by 1a suggests the formation of random copolymers including two and three NBE repeating units. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2575–2580